diff --git a/tests/test_graph_builder.py b/tests/test_graph_builder.py
new file mode 100644
index 0000000..d2c57ed
--- /dev/null
+++ b/tests/test_graph_builder.py
@@ -0,0 +1,120 @@
+import tempfile
+import os
+from pathlib import Path
+from codemap.core import GraphBuilder
+from codemap.parsers import ParsedFile, Dependency
+
+
+def test_graph_builder_basic():
+    builder = GraphBuilder()
+
+    dep = Dependency(
+        module_name="utils",
+        file_path=Path("/app/main.py"),
+        line_number=1
+    )
+    parsed1 = ParsedFile(
+        file_path=Path("/app/main.py"),
+        module_name="main",
+        dependencies=[dep],
+        file_type="python"
+    )
+    parsed2 = ParsedFile(
+        file_path=Path("/app/utils.py"),
+        module_name="utils",
+        dependencies=[],
+        file_type="python"
+    )
+
+    builder.add_file(parsed1)
+    builder.add_file(parsed2)
+
+    stats = builder.get_stats()
+    assert stats["node_count"] == 3
+    assert stats["edge_count"] == 1
+
+
+def test_graph_builder_build_from_files():
+    builder = GraphBuilder()
+
+    files = []
+    for i in range(3):
+        parsed = ParsedFile(
+            file_path=Path(f"/app/module{i}.py"),
+            module_name=f"module{i}",
+            dependencies=[],
+            file_type="python"
+        )
+        files.append(parsed)
+
+    builder.build_from_files(files)
+
+    stats = builder.get_stats()
+    assert stats["node_count"] == 3
+    assert stats["edge_count"] == 0
+
+
+def test_get_dependencies():
+    builder = GraphBuilder()
+
+    dep_a = Dependency(module_name="a", file_path=Path("/app/main.py"), line_number=1)
+    main = ParsedFile(
+        file_path=Path("/app/main.py"),
+        module_name="main",
+        dependencies=[dep_a],
+        file_type="python"
+    )
+    dep_b = Dependency(module_name="b", file_path=Path("/app/utils.py"), line_number=1)
+    utils = ParsedFile(
+        file_path=Path("/app/utils.py"),
+        module_name="utils",
+        dependencies=[dep_b],
+        file_type="python"
+    )
+    a = ParsedFile(
+        file_path=Path("/app/a.py"),
+        module_name="a",
+        dependencies=[],
+        file_type="python"
+    )
+
+    builder.add_file(main)
+    builder.add_file(utils)
+    builder.add_file(a)
+
+    graph_data = builder.get_graph_data()
+    assert len(graph_data.nodes) >= 3
+    assert len(graph_data.edges) >= 2
+
+
+def test_get_packages():
+    builder = GraphBuilder()
+
+    files = [
+        ParsedFile(file_path=Path("/app/src/main.py"), module_name="main", dependencies=[], file_type="python"),
+        ParsedFile(file_path=Path("/app/src/utils.py"), module_name="utils", dependencies=[], file_type="python"),
+        ParsedFile(file_path=Path("/app/lib/helper.py"), module_name="helper", dependencies=[], file_type="python"),
+    ]
+
+    builder.build_from_files(files)
+    packages = builder.get_packages()
+
+    assert "src" in packages or "lib" in packages
+
+
+def test_get_stats():
+    builder = GraphBuilder()
+
+    for i in range(5):
+        parsed = ParsedFile(
+            file_path=Path(f"/app/module{i}.py"),
+            module_name=f"module{i}",
+            dependencies=[],
+            file_type="python"
+        )
+        builder.add_file(parsed)
+
+    stats = builder.get_stats()
+    assert stats["node_count"] == 5
+    assert stats["file_count"] == 5
+    assert stats["edge_count"] == 0