Add log to ddev git (DataDog#21512)

* add log to git.py

* changelog

* Requested changes

* Refactor test

* Add context manager to replace if

* Fix method call

Author: lucia-sb

ddev/changelog.d/21512.added

@@ -0,0 +1 @@
+Adds a new method `log` in the `GitRepository` class. 

ddev/src/ddev/utils/git.py

@@ -68,6 +68,48 @@ def latest_commit(self) -> GitCommit:
         sha, subject = self.capture('log', '-1', '--format=%H%n%s').splitlines()
         return GitCommit(sha, subject=subject)
 
+    def log(self, args: list[str], n: int | None = None, source: str = "HEAD") -> list[dict[str, str]]:
+        """
+        The log is returned as a list of dictionaries where the keys and values of each element are
+        specified from *args. These need to be provided in the format `"<key>:<git_format_placeholder>"`
+
+        Examples:
+            Get the last n commits from `myBranch` getting the hash, author and subject
+
+            git.log("hash:%H", "author:%an", "subject:%s", n=20, source="myBranch")
+
+        """
+        if not args:
+            return []
+
+        keys: list[str] = []
+        format_parts: list[str] = []
+        for arg in args:
+            try:
+                key, format = arg.split(":", 1)
+                keys.append(key)
+                format_parts.append(format)
+            except ValueError as e:
+                raise ValueError(f"Invalid argument: {arg}. Expected format: key:format") from e
+
+        pretty_format = "%x00".join(format_parts)
+        cmd = ['--no-pager', 'log', f"--pretty=format:{pretty_format}"]
+        if n is not None:
+            cmd.append(f"-n {n}")
+
+        cmd.append(source)
+
+        command_output = self.capture(*cmd).strip().splitlines()
+
+        commits: list[dict[str, str]] = []
+
+        for line in command_output:
+            line_parts = line.split("\x00")
+            commit_dict = dict(zip(keys, line_parts, strict=True))
+            commits.append(commit_dict)
+
+        return commits
+
     def pull(self, ref):
         return self.capture('pull', 'origin', ref)
 

ddev/tests/utils/test_git.py

@@ -2,6 +2,7 @@
 # All rights reserved
 # Licensed under a 3-clause BSD style license (see LICENSE)
 import subprocess
+from contextlib import nullcontext
 
 import pytest
 
@@ -10,6 +11,32 @@
 from tests.helpers.git import ClonedRepo
 
 
+@pytest.fixture(scope="module")
+def set_up_repository(local_clone: ClonedRepo):
+    repo = Repository(local_clone.path.name, str(local_clone.path))
+
+    repo.git.capture("config", "user.name", "test_user")
+
+    repo.git.capture("checkout", "master")
+    (repo.path / "test1.txt").touch()
+    repo.git.capture("add", ".")
+    repo.git.capture("commit", "-m", "test1")
+    (repo.path / "test2.txt").touch()
+    repo.git.capture("add", ".")
+    repo.git.capture("commit", "-m", "test2")
+
+    repo.git.capture("checkout", "-b", "my-branch")
+
+    (repo.path / "test3.txt").touch()
+    repo.git.capture("add", ".")
+    repo.git.capture("commit", "-m", "test3")
+
+    repo.git.capture("checkout", "master")
+
+    yield repo
+    local_clone.reset_branch()
+
+
 def test_current_branch(repository):
     repo = Repository(repository.path.name, str(repository.path))
 
@@ -44,6 +71,78 @@ def test_get_latest_commit(repository):
     assert short_sha2 not in commit_status1
 
 
+@pytest.mark.parametrize(
+    "args, n, source, expected, context",
+    [
+        (
+            ["author:%an", "message:%f"],
+            None,
+            None,
+            [
+                {"author": "test_user", "message": "test2"},
+                {"author": "test_user", "message": "test1"},
+            ],
+            nullcontext(),
+        ),
+        (
+            ["author:%an", "message:%f"],
+            2,
+            None,
+            [{"author": "test_user", "message": "test2"}, {"author": "test_user", "message": "test1"}],
+            nullcontext(),
+        ),
+        (
+            ["author:%an", "message:%f"],
+            0,
+            None,
+            [],
+            nullcontext(),
+        ),
+        (
+            ["author:%an", "message:%f"],
+            3,
+            "my-branch",
+            [
+                {"author": "test_user", "message": "test3"},
+                {"author": "test_user", "message": "test2"},
+                {"author": "test_user", "message": "test1"},
+            ],
+            nullcontext(),
+        ),
+        (
+            ["%H", "%f"],
+            1,
+            None,
+            None,
+            pytest.raises(ValueError),
+        ),
+    ],
+    ids=[
+        "test_log_no_n",
+        "test_log_two_commits",
+        "test_log_zero_commits",
+        "test_log_branch_three_commits",
+        "test_log_invalid_format_raises",
+    ],
+)
+def test_get_log(set_up_repository, local_clone, config_file, args, n, source, expected, context):
+    config_file.model.repos['core'] = str(local_clone.path)
+    config_file.save()
+
+    repo = set_up_repository
+    kwargs = {}
+    if n is not None:
+        kwargs['n'] = n
+    if source:
+        kwargs['source'] = source
+
+    with context:
+        if n is None:
+            assert len(expected) < len(repo.git.log(args, **kwargs))
+        else:
+            assert repo.git.log(args, **kwargs) == expected
+
+
 def test_tags(repository):
     repo = Repository(repository.path.name, str(repository.path))