refactor(git): test the git log parser behaves properly when the repository has no commits

We should expect an exception raised or an empty list (no matter what version of git was used).

Author: bhelgs

commitizen/git.py

@@ -82,27 +82,12 @@ def get_commits(
     start: Optional[str] = None,
     end: str = "HEAD",
     *,
-    log_format: str = "%H%n%s%n%an%n%ae%n%b",
-    delimiter: str = "----------commit-delimiter----------",
     args: str = "",
 ) -> List[GitCommit]:
     """Get the commits between start and end."""
-    git_log_cmd = (
-        f"git -c log.showSignature=False log --pretty={log_format}{delimiter} {args}"
-    )
-
-    if start:
-        command = f"{git_log_cmd} {start}..{end}"
-    else:
-        command = f"{git_log_cmd} {end}"
-    c = cmd.run(command)
-    if c.return_code != 0:
-        raise GitCommandError(c.err)
-    if not c.out:
-        return []
-
+    git_log_entries = _get_log_as_str_list(start, end, args)
     git_commits = []
-    for rev_and_commit in c.out.split(f"{delimiter}\n"):
+    for rev_and_commit in git_log_entries:
         if not rev_and_commit:
             continue
         rev, title, author, author_email, *body_list = rev_and_commit.split("\n")
@@ -185,3 +170,22 @@ def is_git_project() -> bool:
     if c.out.strip() == "true":
         return True
     return False
+
+
+def _get_log_as_str_list(start: Optional[str], end: str, args: str) -> List[str]:
+    """Get string representation of each log entry"""
+    delimiter = "----------commit-delimiter----------"
+    log_format: str = "%H%n%s%n%an%n%ae%n%b"
+    git_log_cmd = (
+        f"git -c log.showSignature=False log --pretty={log_format}{delimiter} {args}"
+    )
+    if start:
+        command = f"{git_log_cmd} {start}..{end}"
+    else:
+        command = f"{git_log_cmd} {end}"
+    c = cmd.run(command)
+    if c.return_code != 0:
+        raise GitCommandError(c.err)
+    if not c.out:
+        return []
+    return c.out.split(f"{delimiter}\n")

tests/commands/test_changelog_command.py

@@ -7,7 +7,6 @@
 from commitizen.commands.changelog import Changelog
 from commitizen.exceptions import (
     DryRunExit,
-    GitCommandError,
     NoCommitsFoundError,
     NoRevisionError,
     NotAGitProjectError,
@@ -16,19 +15,6 @@
 from tests.utils import create_file_and_commit, wait_for_tag
 
 
-@pytest.mark.usefixtures("tmp_commitizen_project")
-def test_changelog_on_empty_project(mocker):
-    testargs = ["cz", "changelog", "--dry-run"]
-    mocker.patch.object(sys, "argv", testargs)
-
-    with pytest.raises(GitCommandError):
-        cli.main()
-
-    #  git will error out with something like:
-    #  "your current branch 'XYZ' does not have any commits yet"
-    #  is it wise to assert the exception contains a message like this?
-
-
 @pytest.mark.usefixtures("tmp_commitizen_project")
 def test_changelog_from_version_zero_point_two(mocker, capsys):
     create_file_and_commit("feat: new file")

tests/test_git.py

@@ -4,7 +4,7 @@
 
 import pytest
 
-from commitizen import cmd, git
+from commitizen import cmd, exceptions, git
 from tests.utils import FakeCommand, create_file_and_commit
 
 
@@ -57,6 +57,16 @@ def test_git_message_with_empty_body():
     assert commit.message == commit_title
 
 
+@pytest.mark.usefixtures("tmp_commitizen_project")
+def test_get_log_as_str_list_empty():
+    """ensure an exception or empty list in an empty project"""
+    try:
+        gitlog = git._get_log_as_str_list(start=None, end="HEAD", args="")
+    except exceptions.GitCommandError:
+        return
+    assert len(gitlog) == 0, "list should be empty if no assert"
+
+
 @pytest.mark.usefixtures("tmp_commitizen_project")
 def test_get_commits():
     create_file_and_commit("feat(users): add username")