diff --git a/tests/test_knowledge_gap_identifier.py b/tests/test_knowledge_gap_identifier.py
new file mode 100644
index 0000000..d26ca6d
--- /dev/null
+++ b/tests/test_knowledge_gap_identifier.py
@@ -0,0 +1,141 @@
+"""Tests for knowledge_gap_identifier module."""
+
+import sys
+import os
+import tempfile
+import shutil
+from pathlib import Path
+
+sys.path.insert(0, os.path.join(os.path.dirname(__file__), '..', 'scripts'))
+
+from knowledge_gap_identifier import KnowledgeGapIdentifier, GapType, GapSeverity
+
+
+def _make_repo(tmpdir, structure):
+    """Create a test repo from a dict of {path: content}."""
+    for rel_path, content in structure.items():
+        p = Path(tmpdir) / rel_path
+        p.parent.mkdir(parents=True, exist_ok=True)
+        p.write_text(content)
+
+
+def test_undocumented_symbol():
+    with tempfile.TemporaryDirectory() as tmpdir:
+        _make_repo(tmpdir, {
+            "src/calculator.py": "def add(a, b):\n    return a + b\n",
+            "README.md": "# Calculator\n",
+        })
+        report = KnowledgeGapIdentifier().analyze(tmpdir)
+        undocumented = [g for g in report.gaps if g.gap_type == GapType.UNDOCUMENTED]
+        assert any(g.name == "add" for g in undocumented), "add should be undocumented"
+
+
+def test_documented_symbol_no_gap():
+    with tempfile.TemporaryDirectory() as tmpdir:
+        _make_repo(tmpdir, {
+            "src/calculator.py": "def add(a, b):\n    return a + b\n",
+            "README.md": "# Calculator\nUse `add()` to add numbers.\n",
+        })
+        report = KnowledgeGapIdentifier().analyze(tmpdir)
+        undocumented = [g for g in report.gaps
+                       if g.gap_type == GapType.UNDOCUMENTED and g.name == "add"]
+        assert len(undocumented) == 0, "add is documented, should not be flagged"
+
+
+def test_untested_module():
+    with tempfile.TemporaryDirectory() as tmpdir:
+        _make_repo(tmpdir, {
+            "src/calculator.py": "def add(a, b):\n    return a + b\n",
+            "src/helper.py": "def format(x):\n    return str(x)\n",
+            "tests/test_calculator.py": "from src.calculator import add\nassert add(1,2) == 3\n",
+        })
+        report = KnowledgeGapIdentifier().analyze(tmpdir)
+        untested = [g for g in report.gaps if g.gap_type == GapType.UNTESTED]
+        assert any("helper" in g.name for g in untested), "helper should be untested"
+
+
+def test_tested_module_no_gap():
+    with tempfile.TemporaryDirectory() as tmpdir:
+        _make_repo(tmpdir, {
+            "src/calculator.py": "def add(a, b):\n    return a + b\n",
+            "tests/test_calculator.py": "def test_add():\n    assert True\n",
+        })
+        report = KnowledgeGapIdentifier().analyze(tmpdir)
+        untested = [g for g in report.gaps
+                    if g.gap_type == GapType.UNTESTED and "calculator" in g.name]
+        assert len(untested) == 0, "calculator has tests, should not be flagged"
+
+
+def test_missing_implementation():
+    with tempfile.TemporaryDirectory() as tmpdir:
+        _make_repo(tmpdir, {
+            "src/app.py": "def run():\n    pass\n",
+            "docs/api.md": "# API\nUse `NonExistentClass` to do things.\n",
+        })
+        report = KnowledgeGapIdentifier().analyze(tmpdir)
+        missing = [g for g in report.gaps if g.gap_type == GapType.MISSING_IMPLEMENTATION]
+        assert any(g.name == "NonExistentClass" for g in missing)
+
+
+def test_private_symbols_skipped():
+    with tempfile.TemporaryDirectory() as tmpdir:
+        _make_repo(tmpdir, {
+            "src/app.py": "def _internal():\n    pass\ndef public():\n    pass\n",
+            "README.md": "# App\n",
+        })
+        report = KnowledgeGapIdentifier().analyze(tmpdir)
+        undocumented_names = [g.name for g in report.gaps if g.gap_type == GapType.UNDOCUMENTED]
+        assert "_internal" not in undocumented_names, "Private symbols should be skipped"
+        assert "public" in undocumented_names
+
+
+def test_empty_repo():
+    with tempfile.TemporaryDirectory() as tmpdir:
+        report = KnowledgeGapIdentifier().analyze(tmpdir)
+        assert len(report.gaps) == 0
+
+
+def test_invalid_path():
+    report = KnowledgeGapIdentifier().analyze("/nonexistent/path/xyz")
+    assert len(report.gaps) == 1
+    assert report.gaps[0].severity == GapSeverity.ERROR
+
+
+def test_report_summary():
+    with tempfile.TemporaryDirectory() as tmpdir:
+        _make_repo(tmpdir, {
+            "src/app.py": "class MyService:\n    def handle(self):\n        pass\n",
+            "README.md": "# App\n",
+        })
+        report = KnowledgeGapIdentifier().analyze(tmpdir)
+        summary = report.summary()
+        assert "UNDOCUMENTED" in summary
+        assert "MyService" in summary
+
+
+def test_report_to_dict():
+    with tempfile.TemporaryDirectory() as tmpdir:
+        _make_repo(tmpdir, {
+            "src/app.py": "def hello():\n    pass\n",
+            "README.md": "# App\n",
+        })
+        report = KnowledgeGapIdentifier().analyze(tmpdir)
+        d = report.to_dict()
+        assert "total_gaps" in d
+        assert "gaps" in d
+        assert isinstance(d["gaps"], list)
+        assert d["total_gaps"] > 0
+
+
+if __name__ == "__main__":
+    test_undocumented_symbol()
+    test_documented_symbol_no_gap()
+    test_untested_module()
+    test_tested_module_no_gap()
+    test_missing_implementation()
+    test_private_symbols_skipped()
+    test_empty_repo()
+    test_invalid_path()
+    test_report_summary()
+    test_report_to_dict()
+    print("All 10 tests passed.")