diff --git a/tests/conftest.py b/tests/conftest.py
new file mode 100644
index 0000000..ca56adb
--- /dev/null
+++ b/tests/conftest.py
@@ -0,0 +1,53 @@
+import pytest
+from src.models.data_structures import Author, Commit
+from datetime import datetime
+
+
+@pytest.fixture
+def sample_commit():
+    """Create a sample commit for testing."""
+    return Commit(
+        sha="abc123def456",
+        message="Add new feature",
+        author="Test User",
+        author_email="test@example.com",
+        timestamp=datetime(2024, 1, 15, 10, 30, 0),
+        lines_added=50,
+        lines_deleted=10,
+        files_changed=["src/new_feature.py", "tests/test_new_feature.py"],
+        is_merge=False,
+        is_revert=False,
+    )
+
+
+@pytest.fixture
+def sample_author():
+    """Create a sample author for testing."""
+    return Author(
+        name="Test User",
+        email="test@example.com",
+        commit_count=42,
+        lines_added=5000,
+        lines_deleted=1000,
+    )
+
+
+@pytest.fixture
+def sample_commits():
+    """Create a list of sample commits for testing."""
+    commits = []
+    for i in range(10):
+        commit = Commit(
+            sha=f"sha{i}123{i}",
+            message=f"Commit {i}",
+            author="Test User",
+            author_email="test@example.com",
+            timestamp=datetime(2024, 1, 15, 10 + i, 30, 0),
+            lines_added=10 * i,
+            lines_deleted=2 * i,
+            files_changed=[f"file{i}.py"],
+            is_merge=False,
+            is_revert=False,
+        )
+        commits.append(commit)
+    return commits