Fix git submodule test sha comparison

tests/conftest.py

@@ -136,23 +136,27 @@ def repo_with_submodule():
         # create "parent" repository
         subprocess.check_call(['git', 'init'], cwd=git_a_dir)
         _add_content_to_git(git_a_dir)
-        # create submodule repository
+        # create repository with 2 commits that will be the submodule
         subprocess.check_call(['git', 'init'], cwd=git_b_dir)
         _add_content_to_git(git_b_dir)
+        submod_sha1_b = _get_sha1(git_b_dir)
+        _add_content_to_git(git_b_dir)
 
         # create a new branch in the parent to add the submodule
         subprocess.check_call(['git', 'checkout', '-b', 'branch-with-submod'],
                               cwd=git_a_dir)
         subprocess.check_call(['git', 'submodule', 'add', git_b_dir, 'submod'],
                               cwd=git_a_dir)
+        # checkout the first commit for the submod, not the latest
+        subprocess.check_call(['git', 'checkout', submod_sha1_b],
+                              cwd=os.path.join(git_a_dir, 'submod'))
         subprocess.check_call(['git', 'add', git_a_dir, ".gitmodules"],
                               cwd=git_a_dir)
         subprocess.check_call(['git', 'commit', '-m', 'Add B repos submod'],
                               cwd=git_a_dir)
 
         sha1_a = _get_sha1(git_a_dir)
-        sha1_b = _get_sha1(git_b_dir)
-        yield git_a_dir, sha1_a, sha1_b
+        yield git_a_dir, sha1_a, submod_sha1_b
 
 
 class Repo2DockerTest(pytest.Function):

tests/unit/contentproviders/test_git.py

@@ -21,7 +21,7 @@ def test_clone(repo_with_content):
 
 def test_submodule_clone(repo_with_submodule):
     """Test git clone containing a git submodule."""
-    upstream, sha1_upstream, sha1_submod = repo_with_submodule
+    upstream, expected_sha1_upstream, expected_sha1_submod = repo_with_submodule
 
     with TemporaryDirectory() as clone_dir:
         submod_dir = os.path.join(clone_dir, 'submod')  # set by fixture
@@ -37,8 +37,8 @@ def test_submodule_clone(repo_with_submodule):
         sha1 = subprocess.Popen(cmd, stdout=subprocess.PIPE, cwd=submod_dir)
         submod_sha1 = sha1.stdout.read().decode().strip()
 
-        assert git_content.content_id == sha1_upstream[:7]
-        assert submod_sha1[:7] == submod_sha1[:7]
+        assert git_content.content_id == expected_sha1_upstream[:7]
+        assert submod_sha1[:7] == expected_sha1_submod[:7]
 
 
 def test_bad_ref(repo_with_content):