Re-enable test_mutex

Change-Id: I9356917e18b5584a1c734ecd75c2d75656acab4d
Story: 2000773
Task: 3465

tests/fixtures/config/single-tenant/git/layout-mutex/playbooks/mutex-one.yaml

@@ -0,0 +1,2 @@
+- hosts: all
+  tasks: []

tests/fixtures/config/single-tenant/git/layout-mutex/playbooks/mutex-two.yaml

@@ -0,0 +1,2 @@
+- hosts: all
+  tasks: []

tests/fixtures/config/single-tenant/git/layout-mutex/playbooks/project-test1.yaml

@@ -0,0 +1,2 @@
+- hosts: all
+  tasks: []

tests/fixtures/config/single-tenant/git/layout-mutex/zuul.yaml

@@ -0,0 +1,33 @@
+- pipeline:
+    name: check
+    manager: independent
+    source:
+      gerrit
+    trigger:
+      gerrit:
+        - event: patchset-created
+    success:
+      gerrit:
+        verified: 1
+    failure:
+      gerrit:
+        verified: -1
+
+- job:
+    name: project-test1
+
+- job:
+    name: mutex-one
+    mutex: test-mutex
+
+- job:
+    name: mutex-two
+    mutex: test-mutex
+
+- project:
+    name: org/project
+    check:
+      jobs:
+        - project-test1
+        - mutex-one
+        - mutex-two

tests/fixtures/layout-mutex.yaml

@@ -1,25 +0,0 @@
-pipelines:
-  - name: check
-    manager: IndependentPipelineManager
-    trigger:
-      gerrit:
-        - event: patchset-created
-    success:
-      gerrit:
-        verified: 1
-    failure:
-      gerrit:
-        verified: -1
-
-jobs:
-  - name: mutex-one
-    mutex: test-mutex
-  - name: mutex-two
-    mutex: test-mutex
-
-projects:
-  - name: org/project
-    check:
-      - project-test1
-      - mutex-one
-      - mutex-two

tests/unit/test_scheduler.py

@@ -2182,11 +2182,9 @@ class TestScheduler(ZuulTestCase):
         self.sched.reconfigure(self.config)
         self.assertEqual(len(self.sched.layout.pipelines['gate'].queues), 1)
 
-    @skip("Disabled for early v3 development")
     def test_mutex(self):
         "Test job mutexes"
-        self.config.set('zuul', 'layout_config',
-                        'tests/fixtures/layout-mutex.yaml')
+        self.updateConfigLayout('layout-mutex')
         self.sched.reconfigure(self.config)
 
         self.launch_server.hold_jobs_in_build = True