Refactor gr-rest-api-interface - extract common methods to helper

gr-rest-api-interface contains api for different entities types
and all the code is placed in one file - gr-rest-api-interface.js.
This commit moves all utils methods to a separate GrRestApiHelper
class. After moving, new API can be added as a separate file.
In the future existing API can be refactored as well to provide more
structured access to API. For example, repo API can be exposed as
restAPI.repositories.getConfig(...)

Change-Id: I57f52847aa7e0d4f924f3f5105fc64cd0226d2ff

polygerrit-ui/app/elements/shared/gr-rest-api-interface/gr-rest-api-interface.html

@@ -29,6 +29,7 @@ limitations under the License.
 
 <dom-module id="gr-rest-api-interface">
   <!-- NB: Order is important, because of namespaced classes. -->
+  <script src="gr-rest-apis/gr-rest-api-helper.js"></script>
   <script src="gr-auth.js"></script>
   <script src="gr-reviewer-updates-parser.js"></script>
   <script src="gr-rest-api-interface.js"></script>

polygerrit-ui/app/elements/shared/gr-rest-api-interface/gr-rest-api-interface_test.html

@@ -63,116 +63,8 @@ limitations under the License.
       sandbox.restore();
     });
 
-    suite('fetchJSON()', () => {
-      test('Sets header to accept application/json', () => {
-        const authFetchStub = sandbox.stub(element._auth, 'fetch')
-            .returns(Promise.resolve());
-        element._fetchJSON({url: '/dummy/url'});
-        assert.isTrue(authFetchStub.called);
-        assert.equal(authFetchStub.lastCall.args[1].headers.get('Accept'),
-            'application/json');
-      });
-
-      test('Use header option accept when provided', () => {
-        const authFetchStub = sandbox.stub(element._auth, 'fetch')
-            .returns(Promise.resolve());
-        const headers = new Headers();
-        headers.append('Accept', '*/*');
-        const fetchOptions = {headers};
-        element._fetchJSON({url: '/dummy/url', fetchOptions});
-        assert.isTrue(authFetchStub.called);
-        assert.equal(authFetchStub.lastCall.args[1].headers.get('Accept'),
-            '*/*');
-      });
-    });
-
-    test('JSON prefix is properly removed', done => {
-      element._fetchJSON({url: '/dummy/url'}).then(obj => {
-        assert.deepEqual(obj, {hello: 'bonjour'});
-        done();
-      });
-    });
-
-    test('cached results', done => {
-      let n = 0;
-      sandbox.stub(element, '_fetchJSON', () => {
-        return Promise.resolve(++n);
-      });
-      const promises = [];
-      promises.push(element._fetchSharedCacheURL('/foo'));
-      promises.push(element._fetchSharedCacheURL('/foo'));
-      promises.push(element._fetchSharedCacheURL('/foo'));
-
-      Promise.all(promises).then(results => {
-        assert.deepEqual(results, [1, 1, 1]);
-        element._fetchSharedCacheURL('/foo').then(foo => {
-          assert.equal(foo, 1);
-          done();
-        });
-      });
-    });
-
-    test('cached promise', done => {
-      const promise = Promise.reject(new Error('foo'));
-      element._cache.set('/foo', promise);
-      element._fetchSharedCacheURL({url: '/foo'}).catch(p => {
-        assert.equal(p.message, 'foo');
-        done();
-      });
-    });
-
-    test('cache invalidation', () => {
-      element._cache.set('/foo/bar', 1);
-      element._cache.set('/bar', 2);
-      element._sharedFetchPromises['/foo/bar'] = 3;
-      element._sharedFetchPromises['/bar'] = 4;
-      element._invalidateSharedFetchPromisesPrefix('/foo/');
-      assert.isFalse(element._cache.has('/foo/bar'));
-      assert.isTrue(element._cache.has('/bar'));
-      assert.isUndefined(element._sharedFetchPromises['/foo/bar']);
-      assert.strictEqual(4, element._sharedFetchPromises['/bar']);
-    });
-
-    test('params are properly encoded', () => {
-      let url = element._urlWithParams('/path/', {
-        sp: 'hola',
-        gr: 'guten tag',
-        noval: null,
-      });
-      assert.equal(url,
-          window.CANONICAL_PATH + '/path/?sp=hola&gr=guten%20tag&noval');
-
-      url = element._urlWithParams('/path/', {
-        sp: 'hola',
-        en: ['hey', 'hi'],
-      });
-      assert.equal(url, window.CANONICAL_PATH + '/path/?sp=hola&en=hey&en=hi');
-
-      // Order must be maintained with array params.
-      url = element._urlWithParams('/path/', {
-        l: ['c', 'b', 'a'],
-      });
-      assert.equal(url, window.CANONICAL_PATH + '/path/?l=c&l=b&l=a');
-    });
-
-    test('request callbacks can be canceled', done => {
-      let cancelCalled = false;
-      window.fetch.returns(Promise.resolve({
-        body: {
-          cancel() { cancelCalled = true; },
-        },
-      }));
-      const cancelCondition = () => { return true; };
-      element._fetchJSON({url: '/dummy/url', cancelCondition}).then(
-          obj => {
-            assert.isUndefined(obj);
-            assert.isTrue(cancelCalled);
-            done();
-          });
-    });
-
     test('parent diff comments are properly grouped', done => {
-      sandbox.stub(element, '_fetchJSON', () => {
+      sandbox.stub(element._restApiHelper, 'fetchJSON', () => {
         return Promise.resolve({
           '/COMMIT_MSG': [],
           'sieve.go': [
@@ -315,7 +207,7 @@ limitations under the License.
     test('differing patch diff comments are properly grouped', done => {
       sandbox.stub(element, 'getFromProjectLookup')
           .returns(Promise.resolve('test'));
-      sandbox.stub(element, '_fetchJSON', request => {
+      sandbox.stub(element._restApiHelper, 'fetchJSON', request => {
         const url = request.url;
         if (url === '/changes/test~42/revisions/1') {
           return Promise.resolve({
@@ -432,7 +324,7 @@ limitations under the License.
     suite('rebase action', () => {
       let resolve_fetchJSON;
       setup(() => {
-        sandbox.stub(element, '_fetchJSON').returns(
+        sandbox.stub(element._restApiHelper, 'fetchJSON').returns(
             new Promise(resolve => {
               resolve_fetchJSON = resolve;
             }));
@@ -467,7 +359,7 @@ limitations under the License.
         element.addEventListener('server-error', resolve);
       });
 
-      element._fetchJSON({}).then(response => {
+      element._restApiHelper.fetchJSON({}).then(response => {
         assert.isUndefined(response);
         assert.isTrue(getResponseObjectStub.notCalled);
         serverErrorEventPromise.then(() => done());
@@ -483,12 +375,12 @@ limitations under the License.
           Promise.reject(new Error('Failed to fetch')));
       window.fetch.onSecondCall().returns(Promise.resolve(fakeAuthResponse));
       // Emulate logged in.
-      element._cache.set('/accounts/self/detail', {});
+      element._restApiHelper._cache.set('/accounts/self/detail', {});
       const serverErrorStub = sandbox.stub();
       element.addEventListener('server-error', serverErrorStub);
       const authErrorStub = sandbox.stub();
       element.addEventListener('auth-error', authErrorStub);
-      element._fetchJSON({url: '/bar'}).finally(r => {
+      element._restApiHelper.fetchJSON({url: '/bar'}).finally(r => {
         flush(() => {
           assert.isTrue(authErrorStub.called);
           assert.isFalse(serverErrorStub.called);
@@ -507,7 +399,7 @@ limitations under the License.
       element.addEventListener('server-error', serverErrorStub);
       const authErrorStub = sandbox.stub();
       element.addEventListener('auth-error', authErrorStub);
-      element._fetchJSON({url: '/bar'}).finally(r => {
+      element._restApiHelper.fetchJSON({url: '/bar'}).finally(r => {
         flush(() => {
           assert.isTrue(authErrorStub.called);
           assert.isFalse(serverErrorStub.called);
@@ -558,7 +450,8 @@ limitations under the License.
     test('checkCredentials promise rejection', () => {
       window.fetch.restore();
       element._cache.set('/accounts/self/detail', true);
-      sandbox.spy(element, 'checkCredentials');
+      const checkCredentialsSpy =
+          sandbox.spy(element._restApiHelper, 'checkCredentials');
       sandbox.stub(window, 'fetch', url => {
         return Promise.reject(new Error('Failed to fetch'));
       });
@@ -570,7 +463,7 @@ limitations under the License.
             // The second fetch call also fails, which leads to a second
             // invocation of checkCredentials, which should immediately
             // return instead of making further fetch calls.
-            assert.isTrue(element.checkCredentials.calledTwice);
+            assert.isTrue(checkCredentialsSpy .calledTwice);
             assert.isTrue(window.fetch.calledTwice);
           });
     });
@@ -585,7 +478,7 @@ limitations under the License.
     });
 
     test('legacy n,z key in change url is replaced', () => {
-      const stub = sandbox.stub(element, '_fetchJSON')
+      const stub = sandbox.stub(element._restApiHelper, 'fetchJSON')
           .returns(Promise.resolve([]));
       element.getChanges(1, null, 'n,z');
       assert.equal(stub.lastCall.args[0].params.S, 0);
@@ -593,38 +486,38 @@ limitations under the License.
 
     test('saveDiffPreferences invalidates cache line', () => {
       const cacheKey = '/accounts/self/preferences.diff';
-      sandbox.stub(element, '_send');
+      const sendStub = sandbox.stub(element._restApiHelper, 'send');
       element._cache.set(cacheKey, {tab_size: 4});
       element.saveDiffPreferences({tab_size: 8});
-      assert.isTrue(element._send.called);
+      assert.isTrue(sendStub.called);
-      assert.isFalse(element._cache.has(cacheKey));
+      assert.isFalse(element._restApiHelper._cache.has(cacheKey));
     });
 
     test('getAccount when resp is null does not add anything to the cache',
         done => {
           const cacheKey = '/accounts/self/detail';
-          const stub = sandbox.stub(element, '_fetchSharedCacheURL',
+          const stub = sandbox.stub(element._restApiHelper, 'fetchCacheURL',
               () => Promise.resolve());
 
           element.getAccount().then(() => {
-            assert.isTrue(element._fetchSharedCacheURL.called);
+            assert.isTrue(stub.called);
-            assert.isFalse(element._cache.has(cacheKey));
+            assert.isFalse(element._restApiHelper._cache.has(cacheKey));
             done();
           });
 
-          element._cache.set(cacheKey, 'fake cache');
+          element._restApiHelper._cache.set(cacheKey, 'fake cache');
           stub.lastCall.args[0].errFn();
         });
 
     test('getAccount does not add to the cache when resp.status is 403',
         done => {
           const cacheKey = '/accounts/self/detail';
-          const stub = sandbox.stub(element, '_fetchSharedCacheURL',
+          const stub = sandbox.stub(element._restApiHelper, 'fetchCacheURL',
               () => Promise.resolve());
 
           element.getAccount().then(() => {
-            assert.isTrue(element._fetchSharedCacheURL.called);
+            assert.isTrue(stub.called);
-            assert.isFalse(element._cache.has(cacheKey));
+            assert.isFalse(element._restApiHelper._cache.has(cacheKey));
             done();
           });
           element._cache.set(cacheKey, 'fake cache');
@@ -633,15 +526,15 @@ limitations under the License.
 
     test('getAccount when resp is successful', done => {
       const cacheKey = '/accounts/self/detail';
-      const stub = sandbox.stub(element, '_fetchSharedCacheURL',
+      const stub = sandbox.stub(element._restApiHelper, 'fetchCacheURL',
           () => Promise.resolve());
 
       element.getAccount().then(response => {
-        assert.isTrue(element._fetchSharedCacheURL.called);
+        assert.isTrue(stub.called);
-        assert.equal(element._cache.get(cacheKey), 'fake cache');
+        assert.equal(element._restApiHelper._cache.get(cacheKey), 'fake cache');
         done();
       });
-      element._cache.set(cacheKey, 'fake cache');
+      element._restApiHelper._cache.set(cacheKey, 'fake cache');
 
       stub.lastCall.args[0].errFn({});
     });
@@ -653,7 +546,7 @@ limitations under the License.
       sandbox.stub(element, '_isNarrowScreen', () => {
         return smallScreen;
       });
-      sandbox.stub(element, '_fetchSharedCacheURL', () => {
+      sandbox.stub(element._restApiHelper, 'fetchCacheURL', () => {
         return Promise.resolve(testJSON);
       });
     };
@@ -718,10 +611,10 @@ limitations under the License.
         });
 
     test('savPreferences normalizes download scheme', () => {
-      sandbox.stub(element, '_send');
+      const sendStub = sandbox.stub(element._restApiHelper, 'send');
       element.savePreferences({download_scheme: 'HTTP'});
-      assert.isTrue(element._send.called);
+      assert.isTrue(sendStub.called);
-      assert.equal(element._send.lastCall.args[0].body.download_scheme, 'http');
+      assert.equal(sendStub.lastCall.args[0].body.download_scheme, 'http');
     });
 
     test('getDiffPreferences returns correct defaults', done => {
@@ -747,10 +640,10 @@ limitations under the License.
     });
 
     test('saveDiffPreferences set show_tabs to false', () => {
-      sandbox.stub(element, '_send');
+      const sendStub = sandbox.stub(element._restApiHelper, 'send');
       element.saveDiffPreferences({show_tabs: false});
-      assert.isTrue(element._send.called);
+      assert.isTrue(sendStub.called);
-      assert.equal(element._send.lastCall.args[0].body.show_tabs, false);
+      assert.equal(sendStub.lastCall.args[0].body.show_tabs, false);
     });
 
     test('getEditPreferences returns correct defaults', done => {
@@ -780,33 +673,35 @@ limitations under the License.
     });
 
     test('saveEditPreferences set show_tabs to false', () => {
-      sandbox.stub(element, '_send');
+      const sendStub = sandbox.stub(element._restApiHelper, 'send');
       element.saveEditPreferences({show_tabs: false});
-      assert.isTrue(element._send.called);
+      assert.isTrue(sendStub.called);
-      assert.equal(element._send.lastCall.args[0].body.show_tabs, false);
+      assert.equal(sendStub.lastCall.args[0].body.show_tabs, false);
     });
 
     test('confirmEmail', () => {
-      sandbox.spy(element, '_send');
+      const sendStub = sandbox.spy(element._restApiHelper, 'send');
       element.confirmEmail('foo');
-      assert.isTrue(element._send.calledOnce);
+      assert.isTrue(sendStub.calledOnce);
-      assert.equal(element._send.lastCall.args[0].method, 'PUT');
+      assert.equal(sendStub.lastCall.args[0].method, 'PUT');
-      assert.equal(element._send.lastCall.args[0].url,
+      assert.equal(sendStub.lastCall.args[0].url,
           '/config/server/email.confirm');
-      assert.deepEqual(element._send.lastCall.args[0].body, {token: 'foo'});
+      assert.deepEqual(sendStub.lastCall.args[0].body, {token: 'foo'});
     });
 
     test('setAccountStatus', () => {
-      sandbox.stub(element, '_send').returns(Promise.resolve('OOO'));
+      const sendStub = sandbox.stub(element._restApiHelper, 'send')
+        .returns(Promise.resolve('OOO'));
       element._cache.set('/accounts/self/detail', {});
       return element.setAccountStatus('OOO').then(() => {
-        assert.isTrue(element._send.calledOnce);
+        assert.isTrue(sendStub.calledOnce);
-        assert.equal(element._send.lastCall.args[0].method, 'PUT');
+        assert.equal(sendStub.lastCall.args[0].method, 'PUT');
-        assert.equal(element._send.lastCall.args[0].url,
+        assert.equal(sendStub.lastCall.args[0].url,
             '/accounts/self/status');
-        assert.deepEqual(element._send.lastCall.args[0].body,
+        assert.deepEqual(sendStub.lastCall.args[0].body,
             {status: 'OOO'});
-        assert.deepEqual(element._cache.get('/accounts/self/detail'),
+        assert.deepEqual(element._restApiHelper
+            ._cache.get('/accounts/self/detail'),
            {status: 'OOO'});
       });
     });
@@ -896,18 +791,20 @@ limitations under the License.
       const change_num = '1';
       const file_name = 'index.php';
       const file_contents = '<?php';
-      sandbox.stub(element, '_send').returns(
+      sandbox.stub(element._restApiHelper, 'send').returns(
           Promise.resolve([change_num, file_name, file_contents]));
       sandbox.stub(element, 'getResponseObject')
           .returns(Promise.resolve([change_num, file_name, file_contents]));
       element._cache.set('/changes/' + change_num + '/edit/' + file_name, {});
       return element.saveChangeEdit(change_num, file_name, file_contents)
           .then(() => {
-            assert.isTrue(element._send.calledOnce);
+            assert.isTrue(element._restApiHelper.send.calledOnce);
-            assert.equal(element._send.lastCall.args[0].method, 'PUT');
+            assert.equal(element._restApiHelper.send.lastCall.args[0].method,
-            assert.equal(element._send.lastCall.args[0].url,
+                'PUT');
+            assert.equal(element._restApiHelper.send.lastCall.args[0].url,
                 '/changes/test~1/edit/' + file_name);
-            assert.equal(element._send.lastCall.args[0].body, file_contents);
+            assert.equal(element._restApiHelper.send.lastCall.args[0].body,
+                file_contents);
           });
     });
 
@@ -915,17 +812,18 @@ limitations under the License.
       element._projectLookup = {1: 'test'};
       const change_num = '1';
       const message = 'this is a commit message';
-      sandbox.stub(element, '_send').returns(
+      sandbox.stub(element._restApiHelper, 'send').returns(
           Promise.resolve([change_num, message]));
       sandbox.stub(element, 'getResponseObject')
           .returns(Promise.resolve([change_num, message]));
       element._cache.set('/changes/' + change_num + '/message', {});
       return element.putChangeCommitMessage(change_num, message).then(() => {
-        assert.isTrue(element._send.calledOnce);
+        assert.isTrue(element._restApiHelper.send.calledOnce);
-        assert.equal(element._send.lastCall.args[0].method, 'PUT');
+        assert.equal(element._restApiHelper.send.lastCall.args[0].method, 'PUT');
-        assert.equal(element._send.lastCall.args[0].url,
+        assert.equal(element._restApiHelper.send.lastCall.args[0].url,
             '/changes/test~1/message');
-        assert.deepEqual(element._send.lastCall.args[0].body, {message});
+        assert.deepEqual(element._restApiHelper.send.lastCall.args[0].body,
+            {message});
       });
     });
 
@@ -981,7 +879,7 @@ limitations under the License.
     });
 
     test('createRepo encodes name', () => {
-      const sendStub = sandbox.stub(element, '_send')
+      const sendStub = sandbox.stub(element._restApiHelper, 'send')
           .returns(Promise.resolve());
       return element.createRepo({name: 'x/y'}).then(() => {
         assert.isTrue(sendStub.calledOnce);
@@ -1027,64 +925,65 @@ limitations under the License.
 
     suite('getRepos', () => {
       const defaultQuery = 'state%3Aactive%20OR%20state%3Aread-only';
-
+      let fetchCacheURLStub;
       setup(() => {
-        sandbox.stub(element, '_fetchSharedCacheURL');
+        fetchCacheURLStub =
+            sandbox.stub(element._restApiHelper, 'fetchCacheURL');
       });
 
       test('normal use', () => {
         element.getRepos('test', 25);
-        assert.equal(element._fetchSharedCacheURL.lastCall.args[0].url,
+        assert.equal(fetchCacheURLStub.lastCall.args[0].url,
             '/projects/?n=26&S=0&query=test');
 
         element.getRepos(null, 25);
-        assert.equal(element._fetchSharedCacheURL.lastCall.args[0].url,
+        assert.equal(fetchCacheURLStub.lastCall.args[0].url,
             `/projects/?n=26&S=0&query=${defaultQuery}`);
 
         element.getRepos('test', 25, 25);
-        assert.equal(element._fetchSharedCacheURL.lastCall.args[0].url,
+        assert.equal(fetchCacheURLStub.lastCall.args[0].url,
             '/projects/?n=26&S=25&query=test');
       });
 
       test('with blank', () => {
         element.getRepos('test/test', 25);
-        assert.equal(element._fetchSharedCacheURL.lastCall.args[0].url,
+        assert.equal(fetchCacheURLStub.lastCall.args[0].url,
             '/projects/?n=26&S=0&query=inname%3Atest%20AND%20inname%3Atest');
       });
 
       test('with hyphen', () => {
         element.getRepos('foo-bar', 25);
-        assert.equal(element._fetchSharedCacheURL.lastCall.args[0].url,
+        assert.equal(fetchCacheURLStub.lastCall.args[0].url,
             '/projects/?n=26&S=0&query=inname%3Afoo%20AND%20inname%3Abar');
       });
 
       test('with leading hyphen', () => {
         element.getRepos('-bar', 25);
-        assert.equal(element._fetchSharedCacheURL.lastCall.args[0].url,
+        assert.equal(fetchCacheURLStub.lastCall.args[0].url,
             '/projects/?n=26&S=0&query=inname%3Abar');
       });
 
       test('with trailing hyphen', () => {
         element.getRepos('foo-bar-', 25);
-        assert.equal(element._fetchSharedCacheURL.lastCall.args[0].url,
+        assert.equal(fetchCacheURLStub.lastCall.args[0].url,
             '/projects/?n=26&S=0&query=inname%3Afoo%20AND%20inname%3Abar');
       });
 
       test('with underscore', () => {
         element.getRepos('foo_bar', 25);
-        assert.equal(element._fetchSharedCacheURL.lastCall.args[0].url,
+        assert.equal(fetchCacheURLStub.lastCall.args[0].url,
             '/projects/?n=26&S=0&query=inname%3Afoo%20AND%20inname%3Abar');
       });
 
       test('with underscore', () => {
         element.getRepos('foo_bar', 25);
-        assert.equal(element._fetchSharedCacheURL.lastCall.args[0].url,
+        assert.equal(fetchCacheURLStub.lastCall.args[0].url,
             '/projects/?n=26&S=0&query=inname%3Afoo%20AND%20inname%3Abar');
       });
 
       test('hyphen only', () => {
         element.getRepos('-', 25);
-        assert.equal(element._fetchSharedCacheURL.lastCall.args[0].url,
+        assert.equal(fetchCacheURLStub.lastCall.args[0].url,
             `/projects/?n=26&S=0&query=${defaultQuery}`);
       });
     });
@@ -1113,43 +1012,45 @@ limitations under the License.
     });
 
     suite('getGroups', () => {
+      let fetchCacheURLStub;
       setup(() => {
-        sandbox.stub(element, '_fetchSharedCacheURL');
+        fetchCacheURLStub =
+            sandbox.stub(element._restApiHelper, 'fetchCacheURL');
       });
 
       test('normal use', () => {
         element.getGroups('test', 25);
-        assert.equal(element._fetchSharedCacheURL.lastCall.args[0].url,
+        assert.equal(fetchCacheURLStub.lastCall.args[0].url,
             '/groups/?n=26&S=0&m=test');
 
         element.getGroups(null, 25);
-        assert.equal(element._fetchSharedCacheURL.lastCall.args[0].url,
+        assert.equal(fetchCacheURLStub.lastCall.args[0].url,
             '/groups/?n=26&S=0');
 
         element.getGroups('test', 25, 25);
-        assert.equal(element._fetchSharedCacheURL.lastCall.args[0].url,
+        assert.equal(fetchCacheURLStub.lastCall.args[0].url,
             '/groups/?n=26&S=25&m=test');
       });
 
       test('regex', () => {
         element.getGroups('^test.*', 25);
-        assert.equal(element._fetchSharedCacheURL.lastCall.args[0].url,
+        assert.equal(fetchCacheURLStub.lastCall.args[0].url,
             '/groups/?n=26&S=0&r=%5Etest.*');
 
         element.getGroups('^test.*', 25, 25);
-        assert.equal(element._fetchSharedCacheURL.lastCall.args[0].url,
+        assert.equal(fetchCacheURLStub.lastCall.args[0].url,
             '/groups/?n=26&S=25&r=%5Etest.*');
       });
     });
 
     test('gerrit auth is used', () => {
       sandbox.stub(Gerrit.Auth, 'fetch').returns(Promise.resolve());
-      element._fetchJSON({url: 'foo'});
+      element._restApiHelper.fetchJSON({url: 'foo'});
       assert(Gerrit.Auth.fetch.called);
     });
 
     test('getSuggestedAccounts does not return _fetchJSON', () => {
-      const _fetchJSONSpy = sandbox.spy(element, '_fetchJSON');
+      const _fetchJSONSpy = sandbox.spy(element._restApiHelper, 'fetchJSON');
       return element.getSuggestedAccounts().then(accts => {
         assert.isFalse(_fetchJSONSpy.called);
         assert.equal(accts.length, 0);
@@ -1157,7 +1058,7 @@ limitations under the License.
     });
 
     test('_fetchJSON gets called by getSuggestedAccounts', () => {
-      const _fetchJSONStub = sandbox.stub(element, '_fetchJSON',
+      const _fetchJSONStub = sandbox.stub(element._restApiHelper, 'fetchJSON',
           () => Promise.resolve());
       return element.getSuggestedAccounts('own').then(() => {
         assert.deepEqual(_fetchJSONStub.lastCall.args[0].params, {
@@ -1229,7 +1130,7 @@ limitations under the License.
         const errFn = sinon.stub();
         sandbox.stub(element, 'getChangeActionURL')
             .returns(Promise.resolve(''));
-        sandbox.stub(element, '_fetchRawJSON')
+        sandbox.stub(element._restApiHelper, 'fetchRawJSON')
             .returns(Promise.resolve({ok: false, status: 500}));
         return element._getChangeDetail(123, '516714', errFn).then(() => {
           assert.isTrue(errFn.called);
@@ -1249,11 +1150,12 @@ limitations under the License.
       test('_getChangeDetail populates _projectLookup', () => {
         sandbox.stub(element, 'getChangeActionURL')
             .returns(Promise.resolve(''));
-        sandbox.stub(element, '_fetchRawJSON')
+        sandbox.stub(element._restApiHelper, 'fetchRawJSON')
             .returns(Promise.resolve({ok: true}));
 
         const mockResponse = {_number: 1, project: 'test'};
-        sandbox.stub(element, '_readResponsePayload').returns(Promise.resolve({
+        sandbox.stub(element._restApiHelper, 'readResponsePayload')
+            .returns(Promise.resolve({
               parsed: mockResponse,
               raw: JSON.stringify(mockResponse),
             }));
@@ -1274,7 +1176,8 @@ limitations under the License.
           const mockResponse = {foo: 'bar', baz: 42};
           mockResponseSerial = element.JSON_PREFIX +
               JSON.stringify(mockResponse);
-          sandbox.stub(element, '_urlWithParams').returns(requestUrl);
+          sandbox.stub(element._restApiHelper, 'urlWithParams')
+              .returns(requestUrl);
           sandbox.stub(element, 'getChangeActionURL')
               .returns(Promise.resolve(requestUrl));
           collectSpy = sandbox.spy(element._etags, 'collect');
@@ -1282,7 +1185,8 @@ limitations under the License.
         });
 
         test('contributes to cache', () => {
-          sandbox.stub(element, '_fetchRawJSON').returns(Promise.resolve({
+          sandbox.stub(element._restApiHelper, 'fetchRawJSON')
+              .returns(Promise.resolve({
                 text: () => Promise.resolve(mockResponseSerial),
                 status: 200,
                 ok: true,
@@ -1297,7 +1201,8 @@ limitations under the License.
         });
 
         test('uses cache on HTTP 304', () => {
-          sandbox.stub(element, '_fetchRawJSON').returns(Promise.resolve({
+          sandbox.stub(element._restApiHelper, 'fetchRawJSON')
+              .returns(Promise.resolve({
                 text: () => Promise.resolve(mockResponseSerial),
                 status: 304,
                 ok: true,
@@ -1346,7 +1251,7 @@ limitations under the License.
 
     suite('getChanges populates _projectLookup', () => {
       test('multiple queries', () => {
-        sandbox.stub(element, '_fetchJSON')
+        sandbox.stub(element._restApiHelper, 'fetchJSON')
             .returns(Promise.resolve([
               [
                 {_number: 1, project: 'test'},
@@ -1366,7 +1271,7 @@ limitations under the License.
       });
 
       test('no query', () => {
-        sandbox.stub(element, '_fetchJSON')
+        sandbox.stub(element._restApiHelper, 'fetchJSON')
             .returns(Promise.resolve([
               {_number: 1, project: 'test'},
               {_number: 2, project: 'test'},
@@ -1386,7 +1291,7 @@ limitations under the License.
 
     test('_getChangeURLAndFetch', () => {
       element._projectLookup = {1: 'test'};
-      const fetchStub = sandbox.stub(element, '_fetchJSON')
+      const fetchStub = sandbox.stub(element._restApiHelper, 'fetchJSON')
           .returns(Promise.resolve());
       const req = {changeNum: 1, endpoint: '/test', patchNum: 1};
       return element._getChangeURLAndFetch(req).then(() => {
@@ -1397,7 +1302,7 @@ limitations under the License.
 
     test('_getChangeURLAndSend', () => {
       element._projectLookup = {1: 'test'};
-      const sendStub = sandbox.stub(element, '_send')
+      const sendStub = sandbox.stub(element._restApiHelper, 'send')
           .returns(Promise.resolve());
 
       const req = {
@@ -1419,7 +1324,8 @@ limitations under the License.
         const mockObject = {foo: 'bar', baz: 'foo'};
         const serial = element.JSON_PREFIX + JSON.stringify(mockObject);
         const mockResponse = {text: () => Promise.resolve(serial)};
-        return element._readResponsePayload(mockResponse).then(payload => {
+        return element._restApiHelper.readResponsePayload(mockResponse)
+            .then(payload => {
               assert.deepEqual(payload.parsed, mockObject);
               assert.equal(payload.raw, serial);
             });
@@ -1428,7 +1334,7 @@ limitations under the License.
       test('_parsePrefixedJSON', () => {
         const obj = {x: 3, y: {z: 4}, w: 23};
         const serial = element.JSON_PREFIX + JSON.stringify(obj);
-        const result = element._parsePrefixedJSON(serial);
+        const result = element._restApiHelper.parsePrefixedJSON(serial);
         assert.deepEqual(result, obj);
       });
     });
@@ -1450,7 +1356,7 @@ limitations under the License.
     });
 
     test('generateAccountHttpPassword', () => {
-      const sendSpy = sandbox.spy(element, '_send');
+      const sendSpy = sandbox.spy(element._restApiHelper, 'send');
       return element.generateAccountHttpPassword().then(() => {
         assert.isTrue(sendSpy.calledOnce);
         assert.deepEqual(sendSpy.lastCall.args[0].body, {generate: true});
@@ -1535,11 +1441,12 @@ limitations under the License.
     });
 
     test('getDashboard', () => {
-      const fetchStub = sandbox.stub(element, '_fetchSharedCacheURL');
+      const fetchCacheURLStub = sandbox.stub(element._restApiHelper,
+          'fetchCacheURL');
       element.getDashboard('gerrit/project', 'default:main');
-      assert.isTrue(fetchStub.calledOnce);
+      assert.isTrue(fetchCacheURLStub.calledOnce);
       assert.equal(
-          fetchStub.lastCall.args[0].url,
+          fetchCacheURLStub.lastCall.args[0].url,
           '/projects/gerrit%2Fproject/dashboards/default%3Amain');
     });
 
@@ -1607,7 +1514,7 @@ limitations under the License.
     });
 
     test('_fetch forwards request and logs', () => {
-      const logStub = sandbox.stub(element, '_logCall');
+      const logStub = sandbox.stub(element._restApiHelper, '_logCall');
       const response = {status: 404, text: sinon.stub()};
       const url = 'my url';
       const fetchOptions = {method: 'DELETE'};
@@ -1615,7 +1522,7 @@ limitations under the License.
       const startTime = 123;
       sandbox.stub(Date, 'now').returns(startTime);
       const req = {url, fetchOptions};
-      return element._fetch(req).then(() => {
+      return element._restApiHelper.fetch(req).then(() => {
         assert.isTrue(logStub.calledOnce);
         assert.isTrue(logStub.calledWith(req, startTime, response.status));
         assert.isFalse(response.text.called);
@@ -1627,10 +1534,11 @@ limitations under the License.
       const handler = sinon.stub();
       element.addEventListener('rpc-log', handler);
 
-      element._logCall({url: 'url'}, 100, 200);
+      element._restApiHelper._logCall({url: 'url'}, 100, 200);
       assert.isFalse(handler.called);
 
-      element._logCall({url: 'url', anonymizedUrl: 'not url'}, 100, 200);
+      element._restApiHelper
+          ._logCall({url: 'url', anonymizedUrl: 'not url'}, 100, 200);
       flushAsynchronousOperations();
       assert.isTrue(handler.calledOnce);
     });
@@ -1639,7 +1547,7 @@ limitations under the License.
       sandbox.stub(element, 'getFromProjectLookup')
           .returns(Promise.resolve('test'));
       const sendStub =
-          sandbox.stub(element, '_send').returns(Promise.resolve());
+          sandbox.stub(element._restApiHelper, 'send').returns(Promise.resolve());
 
       await element.saveChangeStarred(123, true);
       assert.isTrue(sendStub.calledOnce);

polygerrit-ui/app/elements/shared/gr-rest-api-interface/gr-rest-apis/gr-rest-api-helper.js

@@ -0,0 +1,456 @@
+/**
+ * @license
+ * Copyright (C) 2019 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+(function(window) {
+  'use strict';
+
+  const Defs = {};
+
+  /**
+   * @typedef {{
+   *    url: string,
+   *    fetchOptions: (Object|null|undefined),
+   *    anonymizedUrl: (string|undefined),
+   * }}
+   */
+  Defs.FetchRequest;
+
+  /**
+   * Object to describe a request for passing into fetchJSON or fetchRawJSON.
+   * - url is the URL for the request (excluding get params)
+   * - errFn is a function to invoke when the request fails.
+   * - cancelCondition is a function that, if provided and returns true, will
+   *     cancel the response after it resolves.
+   * - params is a key-value hash to specify get params for the request URL.
+   * @typedef {{
+   *    url: string,
+   *    errFn: (function(?Response, string=)|null|undefined),
+   *    cancelCondition: (function()|null|undefined),
+   *    params: (Object|null|undefined),
+   *    fetchOptions: (Object|null|undefined),
+   *    anonymizedUrl: (string|undefined),
+   *    reportUrlAsIs: (boolean|undefined),
+   * }}
+   */
+  Defs.FetchJSONRequest;
+
+  const JSON_PREFIX = ')]}\'';
+  const FAILED_TO_FETCH_ERROR = 'Failed to fetch';
+
+  /**
+   * Wrapper around Map for caching server responses. Site-based so that
+   * changes to CANONICAL_PATH will result in a different cache going into
+   * effect.
+   */
+  class SiteBasedCache {
+    constructor() {
+      // Container of per-canonical-path caches.
+      this._data = new Map();
+      if (window.INITIAL_DATA != undefined) {
+        // Put all data shipped with index.html into the cache. This makes it
+        // so that we spare more round trips to the server when the app loads
+        // initially.
+        Object
+            .entries(window.INITIAL_DATA)
+            .forEach(e => this._cache().set(e[0], e[1]));
+      }
+    }
+
+    // Returns the cache for the current canonical path.
+    _cache() {
+      if (!this._data.has(window.CANONICAL_PATH)) {
+        this._data.set(window.CANONICAL_PATH, new Map());
+      }
+      return this._data.get(window.CANONICAL_PATH);
+    }
+
+    has(key) {
+      return this._cache().has(key);
+    }
+
+    get(key) {
+      return this._cache().get(key);
+    }
+
+    set(key, value) {
+      this._cache().set(key, value);
+    }
+
+    delete(key) {
+      this._cache().delete(key);
+    }
+
+    invalidatePrefix(prefix) {
+      const newMap = new Map();
+      for (const [key, value] of this._cache().entries()) {
+        if (!key.startsWith(prefix)) {
+          newMap.set(key, value);
+        }
+      }
+      this._data.set(window.CANONICAL_PATH, newMap);
+    }
+  }
+
+  class FetchPromisesCache {
+    constructor() {
+      this._data = {};
+    }
+
+    has(key) {
+      return !!this._data[key];
+    }
+
+    get(key) {
+      return this._data[key];
+    }
+
+    set(key, value) {
+      this._data[key] = value;
+    }
+
+    invalidatePrefix(prefix) {
+      const newData = {};
+      Object.entries(this._data).forEach(([key, value]) => {
+        if (!key.startsWith(prefix)) {
+          newData[key] = value;
+        }
+      });
+      this._data = newData;
+    }
+  }
+
+  class GrRestApiHelper {
+    /**
+     * @param {SiteBasedCache} cache
+     * @param {object} auth
+     * @param {FetchPromisesCache} fetchPromisesCache
+     * @param {object} credentialCheck
+     * @param {object} restApiInterface
+     */
+    constructor(cache, auth, fetchPromisesCache, credentialCheck,
+        restApiInterface) {
+      this._cache = cache;// TODO: make it public
+      this._auth = auth;
+      this._fetchPromisesCache = fetchPromisesCache;
+      this._credentialCheck = credentialCheck;
+      this._restApiInterface = restApiInterface;
+    }
+
+    /**
+     * Wraps calls to the underlying authenticated fetch function (_auth.fetch)
+     * with timing and logging.
+     * @param {Defs.FetchRequest} req
+     */
+    fetch(req) {
+      const start = Date.now();
+      const xhr = this._auth.fetch(req.url, req.fetchOptions);
+
+      // Log the call after it completes.
+      xhr.then(res => this._logCall(req, start, res ? res.status : null));
+
+      // Return the XHR directly (without the log).
+      return xhr;
+    }
+
+    /**
+     * Log information about a REST call. Because the elapsed time is determined
+     * by this method, it should be called immediately after the request
+     * finishes.
+     * @param {Defs.FetchRequest} req
+     * @param {number} startTime the time that the request was started.
+     * @param {number} status the HTTP status of the response. The status value
+     *     is used here rather than the response object so there is no way this
+     *     method can read the body stream.
+     */
+    _logCall(req, startTime, status) {
+      const method = (req.fetchOptions && req.fetchOptions.method) ?
+          req.fetchOptions.method : 'GET';
+      const endTime = Date.now();
+      const elapsed = (endTime - startTime);
+      const startAt = new Date(startTime);
+      const endAt = new Date(endTime);
+      console.log([
+        'HTTP',
+        status,
+        method,
+        elapsed + 'ms',
+        req.anonymizedUrl || req.url,
+        `(${startAt.toISOString()}, ${endAt.toISOString()})`,
+      ].join(' '));
+      if (req.anonymizedUrl) {
+        this.fire('rpc-log',
+            {status, method, elapsed, anonymizedUrl: req.anonymizedUrl});
+      }
+    }
+
+    /**
+     * Fetch JSON from url provided.
+     * Returns a Promise that resolves to a native Response.
+     * Doesn't do error checking. Supports cancel condition. Performs auth.
+     * Validates auth expiry errors.
+     * @param {Defs.FetchJSONRequest} req
+     */
+    fetchRawJSON(req) {
+      const urlWithParams = this.urlWithParams(req.url, req.params);
+      const fetchReq = {
+        url: urlWithParams,
+        fetchOptions: req.fetchOptions,
+        anonymizedUrl: req.reportUrlAsIs ? urlWithParams : req.anonymizedUrl,
+      };
+      return this.fetch(fetchReq).then(res => {
+        if (req.cancelCondition && req.cancelCondition()) {
+          res.body.cancel();
+          return;
+        }
+        return res;
+      }).catch(err => {
+        const isLoggedIn = !!this._cache.get('/accounts/self/detail');
+        if (isLoggedIn && err && err.message === FAILED_TO_FETCH_ERROR) {
+          this.checkCredentials();
+        } else {
+          if (req.errFn) {
+            req.errFn.call(undefined, null, err);
+          } else {
+            this.fire('network-error', {error: err});
+          }
+        }
+        throw err;
+      });
+    }
+
+    /**
+     * Fetch JSON from url provided.
+     * Returns a Promise that resolves to a parsed response.
+     * Same as {@link fetchRawJSON}, plus error handling.
+     * @param {Defs.FetchJSONRequest} req
+     */
+    fetchJSON(req) {
+      req = this.addAcceptJsonHeader(req);
+      return this.fetchRawJSON(req).then(response => {
+        if (!response) {
+          return;
+        }
+        if (!response.ok) {
+          if (req.errFn) {
+            req.errFn.call(null, response);
+            return;
+          }
+          this.fire('server-error', {request: req, response});
+          return;
+        }
+        return response && this.getResponseObject(response);
+      });
+    }
+
+    /**
+     * @param {string} url
+     * @param {?Object|string=} opt_params URL params, key-value hash.
+     * @return {string}
+     */
+    urlWithParams(url, opt_params) {
+      if (!opt_params) { return this.getBaseUrl() + url; }
+
+      const params = [];
+      for (const p in opt_params) {
+        if (!opt_params.hasOwnProperty(p)) { continue; }
+        if (opt_params[p] == null) {
+          params.push(encodeURIComponent(p));
+          continue;
+        }
+        for (const value of [].concat(opt_params[p])) {
+          params.push(`${encodeURIComponent(p)}=${encodeURIComponent(value)}`);
+        }
+      }
+      return this.getBaseUrl() + url + '?' + params.join('&');
+    }
+
+    /**
+     * @param {!Object} response
+     * @return {?}
+     */
+    getResponseObject(response) {
+      return this.readResponsePayload(response)
+          .then(payload => payload.parsed);
+    }
+
+    /**
+     * @param {!Object} response
+     * @return {!Object}
+     */
+    readResponsePayload(response) {
+      return response.text().then(text => {
+        let result;
+        try {
+          result = this.parsePrefixedJSON(text);
+        } catch (_) {
+          result = null;
+        }
+        return {parsed: result, raw: text};
+      });
+    }
+
+    /**
+     * @param {string} source
+     * @return {?}
+     */
+    parsePrefixedJSON(source) {
+      return JSON.parse(source.substring(JSON_PREFIX.length));
+    }
+
+    /**
+     * @param {Defs.FetchJSONRequest} req
+     * @return {Defs.FetchJSONRequest}
+     */
+    addAcceptJsonHeader(req) {
+      if (!req.fetchOptions) req.fetchOptions = {};
+      if (!req.fetchOptions.headers) req.fetchOptions.headers = new Headers();
+      if (!req.fetchOptions.headers.has('Accept')) {
+        req.fetchOptions.headers.append('Accept', 'application/json');
+      }
+      return req;
+    }
+
+    getBaseUrl() {
+      return this._restApiInterface.getBaseUrl();
+    }
+
+    fire(type, detail, options) {
+      return this._restApiInterface.fire(type, detail, options);
+    }
+
+    /**
+     * @param {Defs.FetchJSONRequest} req
+     */
+    fetchCacheURL(req) {
+      if (this._fetchPromisesCache.has(req.url)) {
+        return this._fetchPromisesCache.get(req.url);
+      }
+      // TODO(andybons): Periodic cache invalidation.
+      if (this._cache.has(req.url)) {
+        return Promise.resolve(this._cache.get(req.url));
+      }
+      this._fetchPromisesCache.set(req.url,
+          this.fetchJSON(req).then(response => {
+            if (response !== undefined) {
+              this._cache.set(req.url, response);
+            }
+            this._fetchPromisesCache.set(req.url, undefined);
+            return response;
+          }).catch(err => {
+            this._fetchPromisesCache.set(req.url, undefined);
+            throw err;
+          })
+      );
+      return this._fetchPromisesCache.get(req.url);
+    }
+
+    /**
+     * Send an XHR.
+     * @param {Defs.SendRequest} req
+     * @return {Promise}
+     */
+    send(req) {
+      const options = {method: req.method};
+      if (req.body) {
+        options.headers = new Headers();
+        options.headers.set(
+            'Content-Type', req.contentType || 'application/json');
+        options.body = typeof req.body === 'string' ?
+            req.body : JSON.stringify(req.body);
+      }
+      if (req.headers) {
+        if (!options.headers) { options.headers = new Headers(); }
+        for (const header in req.headers) {
+          if (!req.headers.hasOwnProperty(header)) { continue; }
+          options.headers.set(header, req.headers[header]);
+        }
+      }
+      const url = req.url.startsWith('http') ?
+          req.url : this.getBaseUrl() + req.url;
+      const fetchReq = {
+        url,
+        fetchOptions: options,
+        anonymizedUrl: req.reportUrlAsIs ? url : req.anonymizedUrl,
+      };
+      const xhr = this.fetch(fetchReq).then(response => {
+        if (!response.ok) {
+          if (req.errFn) {
+            return req.errFn.call(undefined, response);
+          }
+          this.fire('server-error', {request: fetchReq, response});
+        }
+        return response;
+      }).catch(err => {
+        this.fire('network-error', {error: err});
+        if (req.errFn) {
+          return req.errFn.call(undefined, null, err);
+        } else {
+          throw err;
+        }
+      });
+
+      if (req.parseResponse) {
+        return xhr.then(res => this.getResponseObject(res));
+      }
+
+      return xhr;
+    }
+
+    checkCredentials() {
+      if (this._credentialCheck.checking) {
+        return;
+      }
+      this._credentialCheck.checking = true;
+      let req = {url: '/accounts/self/detail', reportUrlAsIs: true};
+      req = this.addAcceptJsonHeader(req);
+      // Skip the REST response cache.
+      return this.fetchRawJSON(req).then(res => {
+        if (!res) { return; }
+        if (res.status === 403) {
+          this.fire('auth-error');
+          this._cache.delete('/accounts/self/detail');
+        } else if (res.ok) {
+          return this.getResponseObject(res);
+        }
+      }).then(res => {
+        this._credentialCheck.checking = false;
+        if (res) {
+          this._cache.set('/accounts/self/detail', res);
+        }
+        return res;
+      }).catch(err => {
+        this._credentialCheck.checking = false;
+        if (err && err.message === FAILED_TO_FETCH_ERROR) {
+          this.fire('auth-error');
+          this._cache.delete('/accounts/self/detail');
+        }
+      });
+    }
+
+    /**
+     * @param {string} prefix
+     */
+    invalidateFetchPromisesPrefix(prefix) {
+      this._fetchPromisesCache.invalidatePrefix(prefix);
+      this._cache.invalidatePrefix(prefix);
+    }
+  }
+
+  window.SiteBasedCache = SiteBasedCache;
+  window.FetchPromisesCache = FetchPromisesCache;
+  window.GrRestApiHelper = GrRestApiHelper;
+})(window);
+

polygerrit-ui/app/elements/shared/gr-rest-api-interface/gr-rest-apis/gr-rest-api-helper_test.html

@@ -0,0 +1,177 @@
+<!DOCTYPE html>
+<!--
+@license
+Copyright (C) 2019 The Android Open Source Project
+
+Licensed under the Apache License, Version 2.0 (the "License");
+you may not use this file except in compliance with the License.
+You may obtain a copy of the License at
+
+http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License.
+-->
+
+<meta name="viewport" content="width=device-width, minimum-scale=1.0, initial-scale=1.0, user-scalable=yes">
+<title>gr-rest-api-helper</title>
+<script src="/test/common-test-setup.js"></script>
+<script src="/bower_components/webcomponentsjs/custom-elements-es5-adapter.js"></script>
+
+<script src="/bower_components/webcomponentsjs/webcomponents-lite.js"></script>
+<script src="/bower_components/web-component-tester/browser.js"></script>
+<link rel="import" href="../../../../test/common-test-setup.html"/>
+<script src="../../../../scripts/util.js"></script>
+<script src="../gr-auth.js"></script>
+<script src="gr-rest-api-helper.js"></script>
+
+<script>void(0);</script>
+
+<script>
+  suite('gr-rest-api-helper tests', () => {
+    let helper;
+    let sandbox;
+    let cache;
+    let fetchPromisesCache;
+
+    setup(() => {
+      sandbox = sinon.sandbox.create();
+      cache = new SiteBasedCache();
+      fetchPromisesCache = new FetchPromisesCache();
+      const credentialCheck = {checking: false};
+
+      window.CANONICAL_PATH = 'testhelper';
+
+      const mockRestApiInterface = {
+        getBaseUrl: sinon.stub().returns(window.CANONICAL_PATH),
+        fire: sinon.stub(),
+      };
+
+      const testJSON = ')]}\'\n{"hello": "bonjour"}';
+      sandbox.stub(window, 'fetch').returns(Promise.resolve({
+        ok: true,
+        text() {
+          return Promise.resolve(testJSON);
+        },
+      }));
+
+      helper = new GrRestApiHelper(cache, Gerrit.Auth, fetchPromisesCache,
+          credentialCheck, mockRestApiInterface);
+    });
+
+    teardown(() => {
+      sandbox.restore();
+    });
+
+    suite('fetchJSON()', () => {
+      test('Sets header to accept application/json', () => {
+        const authFetchStub = sandbox.stub(helper._auth, 'fetch')
+            .returns(Promise.resolve());
+        helper.fetchJSON({url: '/dummy/url'});
+        assert.isTrue(authFetchStub.called);
+        assert.equal(authFetchStub.lastCall.args[1].headers.get('Accept'),
+            'application/json');
+      });
+
+      test('Use header option accept when provided', () => {
+        const authFetchStub = sandbox.stub(helper._auth, 'fetch')
+            .returns(Promise.resolve());
+        const headers = new Headers();
+        headers.append('Accept', '*/*');
+        const fetchOptions = {headers};
+        helper.fetchJSON({url: '/dummy/url', fetchOptions});
+        assert.isTrue(authFetchStub.called);
+        assert.equal(authFetchStub.lastCall.args[1].headers.get('Accept'),
+            '*/*');
+      });
+    });
+
+    test('JSON prefix is properly removed', done => {
+      helper.fetchJSON({url: '/dummy/url'}).then(obj => {
+        assert.deepEqual(obj, {hello: 'bonjour'});
+        done();
+      });
+    });
+
+    test('cached results', done => {
+      let n = 0;
+      sandbox.stub(helper, 'fetchJSON', () => {
+        return Promise.resolve(++n);
+      });
+      const promises = [];
+      promises.push(helper.fetchCacheURL('/foo'));
+      promises.push(helper.fetchCacheURL('/foo'));
+      promises.push(helper.fetchCacheURL('/foo'));
+
+      Promise.all(promises).then(results => {
+        assert.deepEqual(results, [1, 1, 1]);
+        helper.fetchCacheURL('/foo').then(foo => {
+          assert.equal(foo, 1);
+          done();
+        });
+      });
+    });
+
+    test('cached promise', done => {
+      const promise = Promise.reject(new Error('foo'));
+      cache.set('/foo', promise);
+      helper.fetchCacheURL({url: '/foo'}).catch(p => {
+        assert.equal(p.message, 'foo');
+        done();
+      });
+    });
+
+    test('cache invalidation', () => {
+      cache.set('/foo/bar', 1);
+      cache.set('/bar', 2);
+      fetchPromisesCache.set('/foo/bar', 3);
+      fetchPromisesCache.set('/bar', 4);
+      helper.invalidateFetchPromisesPrefix('/foo/');
+      assert.isFalse(cache.has('/foo/bar'));
+      assert.isTrue(cache.has('/bar'));
+      assert.isUndefined(fetchPromisesCache.get('/foo/bar'));
+      assert.strictEqual(4, fetchPromisesCache.get('/bar'));
+    });
+
+    test('params are properly encoded', () => {
+      let url = helper.urlWithParams('/path/', {
+        sp: 'hola',
+        gr: 'guten tag',
+        noval: null,
+      });
+      assert.equal(url,
+          window.CANONICAL_PATH + '/path/?sp=hola&gr=guten%20tag&noval');
+
+      url = helper.urlWithParams('/path/', {
+        sp: 'hola',
+        en: ['hey', 'hi'],
+      });
+      assert.equal(url, window.CANONICAL_PATH + '/path/?sp=hola&en=hey&en=hi');
+
+      // Order must be maintained with array params.
+      url = helper.urlWithParams('/path/', {
+        l: ['c', 'b', 'a'],
+      });
+      assert.equal(url, window.CANONICAL_PATH + '/path/?l=c&l=b&l=a');
+    });
+
+    test('request callbacks can be canceled', done => {
+      let cancelCalled = false;
+      window.fetch.returns(Promise.resolve({
+        body: {
+          cancel() { cancelCalled = true; },
+        },
+      }));
+      const cancelCondition = () => { return true; };
+      helper.fetchJSON({url: '/dummy/url', cancelCondition}).then(
+          obj => {
+            assert.isUndefined(obj);
+            assert.isTrue(cancelCalled);
+            done();
+          });
+    });
+  });
+</script>

polygerrit-ui/app/template_test_srcs/template_test.js

@@ -35,6 +35,9 @@ const EXTERN_NAMES = [
   'GrReviewerUpdatesParser',
   'GrCountStringFormatter',
   'GrThemeApi',
+  'SiteBasedCache',
+  'FetchPromisesCache',
+  'GrRestApiHelper',
   'moment',
   'page',
   'util',

polygerrit-ui/app/test/index.html

@@ -187,6 +187,7 @@ limitations under the License.
     'shared/gr-rest-api-interface/gr-auth_test.html',
     'shared/gr-rest-api-interface/gr-rest-api-interface_test.html',
     'shared/gr-rest-api-interface/gr-reviewer-updates-parser_test.html',
+    'shared/gr-rest-api-interface/gr-rest-apis/gr-rest-api-helper_test.html',
     'shared/gr-select/gr-select_test.html',
     'shared/gr-storage/gr-storage_test.html',
     'shared/gr-textarea/gr-textarea_test.html',