Add a multi-language CRAP tool that writes .metrics/crap.edn for uml-viewer.

Score Clojure, Java, Go, TypeScript, Rust, and Python with each language's complexity rules and coverage report.

tests/test_crap.py

@@ -0,0 +1,73 @@
+from crapper.crap import crap_score, sort_entries
+from crapper.metrics import render_edn
+from crapper.model import Entry
+from crapper.report import format_report
+
+
+def entry(**kwargs):
+    defaults = dict(
+        name="score",
+        namespace="demo.core",
+        complexity=1,
+        coverage=100.0,
+        crap=1.0,
+        path="src/demo/core.clj",
+        language="clojure",
+    )
+    defaults.update(kwargs)
+    return Entry(**defaults)
+
+
+def test_formula_matches_crap4clj():
+    assert crap_score(5, 100.0) == 5.0
+    assert crap_score(5, 0.0) == 30.0
+    assert crap_score(1, 100.0) == 1.0
+    assert abs(crap_score(8, 45.0) - 18.648) < 0.01
+    assert crap_score(3, None) is None
+
+
+def test_unscored_rows_sort_after_scored_rows():
+    rows = sort_entries(
+        [
+            entry(name="missing", crap=None, coverage=None),
+            entry(name="mid", crap=5.0),
+            entry(name="worst", crap=30.0),
+        ]
+    )
+    assert [row.name for row in rows] == ["worst", "mid", "missing"]
+
+
+def test_unscored_rows_sort_by_complexity():
+    rows = sort_entries(
+        [
+            entry(name="small", crap=None, coverage=None, complexity=1),
+            entry(name="large", crap=None, coverage=None, complexity=8),
+        ]
+    )
+    assert [row.name for row in rows] == ["large", "small"]
+
+
+def test_report_shows_na_for_missing_coverage():
+    text = format_report([entry(coverage=None, crap=None, complexity=3)])
+    assert "CRAP Report" in text
+    assert "N/A" in text
+    assert "demo.core" in text
+
+
+def test_edn_uses_crap4clj_keys():
+    text = render_edn(
+        [entry(name="layout", namespace="uml-viewer.layout", complexity=8, coverage=82.0, crap=3.4)]
+    )
+    assert text.startswith("{:entries [")
+    assert ':name "layout"' in text
+    assert ':namespace "uml-viewer.layout"' in text
+    assert ":complexity 8" in text
+    assert ":coverage 82.0" in text
+    assert ":crap 3.4" in text
+    assert text.endswith("}\n")
+
+
+def test_edn_writes_nil_for_missing_coverage():
+    text = render_edn([entry(coverage=None, crap=None)])
+    assert ":coverage nil" in text
+    assert ":crap nil" in text