tests: Disallow use of util.subp except for where needed.

In many cases, cloud-init uses 'util.subp' to run a subprocess.
This is not really desirable in our unit tests as it makes the tests
dependent upon existance of those utilities.

The change here is to modify the base test case class (CiTestCase) to
raise exception any time subp is called.  Then, fix all callers.
For cases where subp is necessary or actually desired, we can use it
via
  a.) context hander CiTestCase.allow_subp(value)
  b.) class level self.allowed_subp = value

Both cases the value is a list of acceptable executable names that
will be called (essentially argv[0]).

Some cleanups in AltCloud were done as the code was being updated.

1 files changed, 15 insertions, 12 deletions

diff --git a/tests/unittests/test_util.py b/tests/unittests/test_util.py
index 7a203ce2..5a14479a 100644
--- a/tests/unittests/test_util.py
+++ b/tests/unittests/test_util.py
@@ -24,6 +24,7 @@ except ImportError:
 
 
 BASH = util.which('bash')
+BOGUS_COMMAND = 'this-is-not-expected-to-be-a-program-name'
 
 
 class FakeSelinux(object):
@@ -742,6 +743,8 @@ class TestReadSeeded(helpers.TestCase):
 
 class TestSubp(helpers.CiTestCase):
     with_logs = True
+    allowed_subp = [BASH, 'cat', helpers.CiTestCase.SUBP_SHELL_TRUE,
+                    BOGUS_COMMAND, sys.executable]
 
     stdin2err = [BASH, '-c', 'cat >&2']
     stdin2out = ['cat']
@@ -749,7 +752,6 @@ class TestSubp(helpers.CiTestCase):
     utf8_valid = b'start \xc3\xa9 end'
     utf8_valid_2 = b'd\xc3\xa9j\xc8\xa7'
     printenv = [BASH, '-c', 'for n in "$@"; do echo "$n=${!n}"; done', '--']
-    bogus_command = 'this-is-not-expected-to-be-a-program-name'
 
     def printf_cmd(self, *args):
         # bash's printf supports \xaa.  So does /usr/bin/printf
@@ -848,9 +850,10 @@ class TestSubp(helpers.CiTestCase):
         util.write_file(noshebang, 'true\n')
 
         os.chmod(noshebang, os.stat(noshebang).st_mode | stat.S_IEXEC)
-        self.assertRaisesRegex(util.ProcessExecutionError,
-                               r'Missing #! in script\?',
-                               util.subp, (noshebang,))
+        with self.allow_subp([noshebang]):
+            self.assertRaisesRegex(util.ProcessExecutionError,
+                                   r'Missing #! in script\?',
+                                   util.subp, (noshebang,))
 
     def test_subp_combined_stderr_stdout(self):
         """Providing combine_capture as True redirects stderr to stdout."""
@@ -868,14 +871,14 @@ class TestSubp(helpers.CiTestCase):
     def test_exception_has_out_err_are_bytes_if_decode_false(self):
         """Raised exc should have stderr, stdout as bytes if no decode."""
         with self.assertRaises(util.ProcessExecutionError) as cm:
-            util.subp([self.bogus_command], decode=False)
+            util.subp([BOGUS_COMMAND], decode=False)
         self.assertTrue(isinstance(cm.exception.stdout, bytes))
         self.assertTrue(isinstance(cm.exception.stderr, bytes))
 
     def test_exception_has_out_err_are_bytes_if_decode_true(self):
         """Raised exc should have stderr, stdout as string if no decode."""
         with self.assertRaises(util.ProcessExecutionError) as cm:
-            util.subp([self.bogus_command], decode=True)
+            util.subp([BOGUS_COMMAND], decode=True)
         self.assertTrue(isinstance(cm.exception.stdout, six.string_types))
         self.assertTrue(isinstance(cm.exception.stderr, six.string_types))
 
@@ -925,10 +928,10 @@ class TestSubp(helpers.CiTestCase):
             logs.append(log)
 
         with self.assertRaises(util.ProcessExecutionError):
-            util.subp([self.bogus_command], status_cb=status_cb)
+            util.subp([BOGUS_COMMAND], status_cb=status_cb)
 
         expected = [
-            'Begin run command: {cmd}\n'.format(cmd=self.bogus_command),
+            'Begin run command: {cmd}\n'.format(cmd=BOGUS_COMMAND),
             'ERROR: End run command: invalid command provided\n']
         self.assertEqual(expected, logs)
 
@@ -940,13 +943,13 @@ class TestSubp(helpers.CiTestCase):
             logs.append(log)
 
         with self.assertRaises(util.ProcessExecutionError):
-            util.subp(['ls', '/I/dont/exist'], status_cb=status_cb)
-        util.subp(['ls'], status_cb=status_cb)
+            util.subp([BASH, '-c', 'exit 2'], status_cb=status_cb)
+        util.subp([BASH, '-c', 'exit 0'], status_cb=status_cb)
 
         expected = [
-            'Begin run command: ls /I/dont/exist\n',
+            'Begin run command: %s -c exit 2\n' % BASH,
             'ERROR: End run command: exit(2)\n',
-            'Begin run command: ls\n',
+            'Begin run command: %s -c exit 0\n' % BASH,
             'End run command: exit(0)\n']
         self.assertEqual(expected, logs)