reimplement incoming check via git log (#3997)

fixes #3975

Author: vladak

tools/src/main/python/opengrok_tools/scm/git.py

@@ -52,8 +52,22 @@ def reposync(self):
         return self._run_custom_sync_command([self.command, 'pull', '--ff-only'])
 
     def incoming_check(self):
+        """
+        :return: True if there are any incoming changes present, False otherwise
+        """
         self._configure_git_pull()
-        return self._run_custom_incoming_command([self.command, 'pull', '--dry-run'])
+        self.fetch()
+        branch = self.get_branch()
+        status, out = self._run_command([self.command, 'log',
+                                         '--pretty=tformat:%H', '..origin/' + branch])
+        if status == 0:
+            if len(out) == 0:
+                return False
+        else:
+            raise RepositoryException("failed to check for incoming changes in {}: {}".
+                                      format(self, status))
+
+        return True
 
     def get_branch(self):
         status, out = self._run_command([self.command, 'branch', '--show-current'])

tools/src/test/python/test_mirror_incoming_retval.py

@@ -34,21 +34,25 @@
 
 import opengrok_tools.mirror
 from opengrok_tools.scm import get_repository
-from opengrok_tools.utils.exitvals import CONTINUE_EXITVAL
+from opengrok_tools.utils.exitvals import CONTINUE_EXITVAL, SUCCESS_EXITVAL
 
 
+@pytest.fixture(scope="module", autouse=True)
+def setup():
+    # The default has changed for python 3.8 (see https://github.com/oracle/opengrok/issues/3296).
+    # Because of the mocking we need to use the "fork" type to propagate all mocks to the
+    # processes spawned by mirror command
+    multiprocessing.set_start_method('fork')
+
+
+@pytest.mark.parametrize('do_changes', [True, False])
 @pytest.mark.skipif(not os.name.startswith("posix"), reason="requires posix")
-def test_incoming_retval(monkeypatch):
+def test_incoming_retval(monkeypatch, do_changes):
     """
     Test that the special CONTINUE_EXITVAL value bubbles all the way up to
     the mirror.py return value.
     """
 
-    # The default has changed for python 3.8 (see https://github.com/oracle/opengrok/issues/3296).
-    # Because of the mocking we need to use the "fork" type to propagate all mocks to the
-    # processes spawned by mirror command
-    multiprocessing.set_start_method('fork')
-
     class MockResponse:
 
         # mock json() method always returns a specific testing dictionary
@@ -65,7 +69,9 @@ def raise_for_status():
         repo_path = os.path.join(source_root, repo_name)
         cloned_repo_name = "cloned_repo"
         cloned_repo_path = os.path.join(source_root, cloned_repo_name)
-        project_name = "foo"  # does not matter for this test
+        # The project name does not matter for this test except for the lock file created by main()
+        # so that both parametrized tests can run in parallel.
+        project_name = "test_incoming_retval-" + str(do_changes)
 
         os.mkdir(repo_path)
 
@@ -85,15 +91,25 @@ def mock_get_config_value(*args, **kwargs):
             git_config.set_value('user', 'email', '[email protected]')
             git_config.set_value('user', 'name', 'John Doe')
 
-        new_file_path = os.path.join(repo_path, 'foo')
+        # Add a file.
+        new_file_path = os.path.join(repo_path, 'newfile')
         with open(new_file_path, 'w'):
             pass
         assert os.path.isfile(new_file_path)
         index = repo.index
         index.add([new_file_path])
         index.commit("add file")
+
+        # Clone the repository first so that any subsequent changes in the repo
+        # will not be reflected in the clone.
         repo.clone(cloned_repo_path)
 
+        if do_changes:
+            with open(new_file_path, 'w') as fp:
+                fp.write("foo")
+            index.add([new_file_path])
+            index.commit("change file")
+
         with monkeypatch.context() as m:
             m.setattr(sys, 'argv', ['prog', "-I", project_name])
 
@@ -103,4 +119,9 @@ def mock_get_config_value(*args, **kwargs):
             m.setattr("opengrok_tools.utils.mirror.get_repos_for_project", mock_get_repos)
             m.setattr("opengrok_tools.utils.mirror.do_api_call", mock_get)
 
-            assert opengrok_tools.mirror.main() == CONTINUE_EXITVAL
+            if do_changes:
+                expected_retval = SUCCESS_EXITVAL
+            else:
+                expected_retval = CONTINUE_EXITVAL
+
+            assert opengrok_tools.mirror.main() == expected_retval