feat: Add comprehensive test suite for stats module with git-related functions

aider/stats.py

@@ -3,14 +3,31 @@ import sys
 
 from collections import defaultdict
 
+# Length of abbreviated git hash used in blame output
 hash_len = len("44e6fefc2")
 
 def run(cmd):
-    # Get all commit hashes since the specified tag
+    """Execute a git command and return its output.
+    
+    Args:
+        cmd: List containing the command and its arguments
+        
+    Returns:
+        String output of the command
+    """
     result = subprocess.run(cmd, capture_output=True, text=True, check=True)
     return result.stdout
 
 def get_all_commit_hashes_between_tags(start_tag, end_tag=None):
+    """Get all commit hashes between two tags or from a tag to HEAD.
+    
+    Args:
+        start_tag: Starting tag or commit hash
+        end_tag: Ending tag or commit hash (defaults to HEAD)
+        
+    Returns:
+        List of commit hashes or None if no commits found
+    """
     if end_tag:
         res = run(["git", "rev-list", f"{start_tag}..{end_tag}"])
     else:
@@ -19,8 +36,17 @@ def get_all_commit_hashes_between_tags(start_tag, end_tag=None):
     if res:
         commit_hashes = res.strip().split("\n")
         return commit_hashes
+    return None
 
 def get_commit_authors(commits):
+    """Map commit hashes to their authors, marking aider-generated commits.
+    
+    Args:
+        commits: List of commit hashes
+        
+    Returns:
+        Dictionary mapping commit hashes to author names
+    """
     commit_to_author = dict()
     for commit in commits:
         author = run(["git", "show", "-s", "--format=%an", commit]).strip()
@@ -31,6 +57,17 @@ def get_commit_authors(commits):
     return commit_to_author
 
 def get_counts_for_file(start_tag, end_tag, authors, fname):
+    """Count lines attributed to each author in a file using git blame.
+    
+    Args:
+        start_tag: Starting tag or commit hash
+        end_tag: Ending tag or commit hash (defaults to HEAD)
+        authors: Dictionary mapping commit hashes to author names
+        fname: File path to analyze
+        
+    Returns:
+        Dictionary mapping author names to line counts, or None if file not found
+    """
     try:
         if end_tag:
             text = run(

tests/test_stats.py

@@ -0,0 +1,119 @@
+import unittest
+import subprocess
+from unittest.mock import patch, MagicMock
+from collections import defaultdict
+
+from aider.stats import (
+    get_all_commit_hashes_between_tags,
+    get_commit_authors,
+    get_counts_for_file,
+    hash_len,
+)
+
+
+class TestStats(unittest.TestCase):
+    @patch("aider.stats.run")
+    def test_get_all_commit_hashes_between_tags(self, mock_run):
+        # Test with end_tag
+        mock_run.return_value = "commit1\ncommit2\ncommit3"
+        result = get_all_commit_hashes_between_tags("v1.0.0", "v2.0.0")
+        mock_run.assert_called_with(["git", "rev-list", "v1.0.0..v2.0.0"])
+        self.assertEqual(result, ["commit1", "commit2", "commit3"])
+
+        # Test without end_tag (defaults to HEAD)
+        mock_run.return_value = "commit4\ncommit5"
+        result = get_all_commit_hashes_between_tags("v1.0.0")
+        mock_run.assert_called_with(["git", "rev-list", "v1.0.0..HEAD"])
+        self.assertEqual(result, ["commit4", "commit5"])
+
+        # Test with empty result
+        mock_run.return_value = ""
+        result = get_all_commit_hashes_between_tags("v1.0.0", "v1.0.0")
+        self.assertEqual(result, None)
+
+    @patch("aider.stats.run")
+    def test_get_commit_authors(self, mock_run):
+        # Setup mock responses for git show commands
+        def mock_run_side_effect(cmd):
+            if cmd[0:3] == ["git", "show", "-s"]:
+                if "--format=%an" in cmd:
+                    if cmd[-1] == "commit1":
+                        return "Author1\n"
+                    elif cmd[-1] == "commit2":
+                        return "Author2\n"
+                elif "--format=%s" in cmd:
+                    if cmd[-1] == "commit1":
+                        return "Normal commit message\n"
+                    elif cmd[-1] == "commit2":
+                        return "aider: AI generated commit\n"
+            return ""
+
+        mock_run.side_effect = mock_run_side_effect
+        
+        # Test author attribution with aider tag
+        commits = ["commit1", "commit2"]
+        result = get_commit_authors(commits)
+        
+        expected = {
+            "commit1": "Author1",
+            "commit2": "Author2 (aider)",
+        }
+        self.assertEqual(result, expected)
+
+    @patch("aider.stats.run")
+    def test_get_counts_for_file(self, mock_run):
+        # Setup mock for git blame
+        blame_output = f"""
+{hash_len * '0'} (Author1 2023-01-01 12:00:00 +0000 1) Line 1
+{hash_len * '1'} (Author2 2023-01-02 12:00:00 +0000 2) Line 2
+{hash_len * '1'} (Author2 2023-01-02 12:00:00 +0000 3) Line 3
+^{hash_len * '2'} (Author3 2023-01-03 12:00:00 +0000 4) Line 4 (not counted - from before start_tag)
+"""
+        mock_run.return_value = blame_output.strip()
+        
+        # Mock authors dictionary
+        authors = {
+            "0" * hash_len: "Author1",
+            "1" * hash_len: "Author2 (aider)",
+        }
+        
+        # Test with end_tag
+        result = get_counts_for_file("v1.0.0", "v2.0.0", authors, "test_file.py")
+        mock_run.assert_called_with([
+            "git", "blame", "-M", "-C", "-C", "--abbrev=9", 
+            "v1.0.0..v2.0.0", "--", "test_file.py"
+        ])
+        
+        expected = {
+            "Author1": 1,
+            "Author2 (aider)": 2,
+        }
+        self.assertEqual(result, expected)
+        
+        # Test with no end_tag
+        result = get_counts_for_file("v1.0.0", None, authors, "test_file.py")
+        mock_run.assert_called_with([
+            "git", "blame", "-M", "-C", "-C", "--abbrev=9", 
+            "v1.0.0..HEAD", "--", "test_file.py"
+        ])
+
+    @patch("aider.stats.run")
+    def test_get_counts_for_file_error_handling(self, mock_run):
+        # Test file not found error
+        error = subprocess.CalledProcessError(1, "git blame", stderr=b"no such path 'nonexistent.py'")
+        mock_run.side_effect = error
+        
+        result = get_counts_for_file("v1.0.0", "v2.0.0", {}, "nonexistent.py")
+        self.assertIsNone(result)
+        
+        # Test other git error
+        error = subprocess.CalledProcessError(1, "git blame", stderr=b"some other git error")
+        mock_run.side_effect = error
+        
+        with patch("sys.stderr"):  # Suppress stderr output during test
+            result = get_counts_for_file("v1.0.0", "v2.0.0", {}, "test_file.py")
+            self.assertIsNone(result)
+
+
+if __name__ == "__main__":
+    unittest.main()