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_rust.py

@@ -0,0 +1,95 @@
+from crapper.languages.rust import functions_in_source
+
+SOURCE = """
+pub fn choose(x: i32) -> i32 {
+    if x > 0 && x < 10 {
+        return 1;
+    }
+    match x {
+        1 => 1,
+        2 => 2,
+        _ => 0,
+    }
+}
+
+impl Sample {
+    pub fn run(&self) -> i32 {
+        if self.ok { 1 } else { 0 }
+    }
+}
+
+impl Trait for Sample {
+    fn draw(&mut self) {}
+}
+
+mod tests {
+    fn hidden() {
+        if true {}
+    }
+}
+
+fn outer() {
+    fn inner() {
+        if true {}
+    }
+}
+"""
+
+
+def test_functions_methods_and_skipped_tests(tmp_path):
+    (tmp_path / "Cargo.toml").write_text(
+        '[package]\nname = "demo-game"\nversion = "0.1.0"\n',
+        encoding="utf-8",
+    )
+    path = tmp_path / "src" / "lib.rs"
+    path.parent.mkdir()
+    path.write_text(SOURCE, encoding="utf-8")
+    functions = functions_in_source(SOURCE, "src/lib.rs", str(tmp_path))
+    assert [(fn.namespace, fn.name, fn.complexity) for fn in functions] == [
+        ("demo_game", "choose", 6),
+        ("demo_game::Sample", "run", 2),
+        ("demo_game::Sample", "draw", 1),
+        ("demo_game", "outer", 2),
+    ]
+
+
+def test_impl_for_a_nested_generic_type(tmp_path):
+    (tmp_path / "Cargo.toml").write_text(
+        '[package]\nname = "demo"\nversion = "0.1.0"\n',
+        encoding="utf-8",
+    )
+    source = "impl Trait for Vec<crate::Sample> {\n    fn draw(&self) {}\n}\n"
+    functions = functions_in_source(source, str(tmp_path / "src" / "lib.rs"), str(tmp_path))
+    assert functions[0].name == "draw"
+    assert functions[0].namespace.endswith("Vec") or "Sample" in functions[0].namespace
+
+
+def test_module_paths_outside_the_usual_layout(tmp_path):
+    (tmp_path / "Cargo.toml").write_text(
+        '[package]\nname = "demo"\nversion = "0.1.0"\n',
+        encoding="utf-8",
+    )
+    mod = "pub fn open() {}\n"
+    binary = "pub fn main_ok() {}\n"
+    functions_in_source(mod, str(tmp_path / "src" / "game" / "mod.rs"), str(tmp_path))
+    functions = functions_in_source(binary, str(tmp_path / "src" / "bin" / "tool.rs"), str(tmp_path))
+    assert functions[0].namespace == "tool"
+    outside = functions_in_source("pub fn loose() {}\n", "/tmp/loose.rs", str(tmp_path))
+    assert outside[0].name == "loose"
+    bare = functions_in_source("pub fn bare() {}\n", str(tmp_path / "notes.rs"), None)
+    assert bare[0].name == "bare"
+
+
+def test_nested_module_path(tmp_path):
+    (tmp_path / "Cargo.toml").write_text(
+        '[package]\nname = "demo"\nversion = "0.1.0"\n',
+        encoding="utf-8",
+    )
+    path = tmp_path / "src" / "game" / "board.rs"
+    path.parent.mkdir(parents=True)
+    source = "pub fn place() -> i32 { if ready { 1 } else { 0 } }\n"
+    path.write_text(source, encoding="utf-8")
+    functions = functions_in_source(source, "src/game/board.rs", str(tmp_path))
+    assert [(fn.namespace, fn.name, fn.complexity) for fn in functions] == [
+        ("demo::game::board", "place", 2)
+    ]