Skip test depending on sqlite3 if unavailable

Fixes bug 973626

Add @depends_on_exe to declare a test dependency on the availability
of an executable.

Skip TestSqlite.test_big_int_mapping if sqlite3 not available on the
local PATH.

Change-Id: I1b7cf0636f79422f9f31f6a88a493791897a53b4

glance/tests/functional/test_sqlite.py

@@ -19,13 +19,15 @@
 
 
 from glance.tests import functional
-from glance.tests.utils import execute
+from glance.tests.utils import execute, depends_on_exe, skip_if_disabled
 
 
 class TestSqlite(functional.FunctionalTest):
     """Functional tests for sqlite-specific logic"""
 
     @functional.runs_sql
+    @depends_on_exe('sqlite3')
+    @skip_if_disabled
     def test_big_int_mapping(self):
         """Ensure BigInteger not mapped to BIGINT"""
         self.cleanup()

glance/tests/utils.py

@@ -178,6 +178,24 @@ class requires(object):
         return _runner
 
 
+class depends_on_exe(object):
+    """Decorator to skip test if an executable is unavailable"""
+    def __init__(self, exe):
+        self.exe = exe
+
+    def __call__(self, func):
+        def _runner(*args, **kw):
+            cmd = 'which %s' % self.exe
+            exitcode, out, err = execute(cmd, raise_error=False)
+            if exitcode != 0:
+                args[0].disabled_message = 'test requires exe: %s' % self.exe
+                args[0].disabled = True
+            func(*args, **kw)
+        _runner.__name__ = func.__name__
+        _runner.__doc__ = func.__doc__
+        return _runner
+
+
 def skip_if_disabled(func):
     """Decorator that skips a test if test case is disabled."""
     @functools.wraps(func)