unclebob / crapper

# crapper
CRAP scores for Clojure, Java, Go, TypeScript, Rust, and Python. One run detects the language of each source file, applies that language's complexity and coverage rules, and writes the snapshot uml-viewer already reads.
The formula is the one from crap4clj, crap4java, and crap4go:
 [code] 
`CC` is cyclomatic complexity. `coverage` is the fraction of the function exercised by tests. A score of 1–5 is low risk, 5–30 is worth a look, and 30+ is complex and under-tested.
## Run
 [code] 
The first run creates `.venv` and installs the tool. From a project root it walks the tree, skips `test`, `spec`, `vendor`, `node_modules`, and `target`, and writes two results:
- a table on stdout, worst score first
- `.metrics/crap.edn`, replaced on every successful analysis
 [code] 
## Snapshot
`.metrics/crap.edn` has the same shape crap4clj writes:
 [code] 
uml-viewer groups entries by `:namespace` and joins each operation on `:name`. `nil` coverage is what `--no-coverage` writes: complexity only, and CRAP is `nil` too. A function the coverage report does not mention scores 0%.
| Language | `:namespace` | `:name` |
| --- | --- | --- |
| Clojure | the `ns` | the `defn` / `defn-` name |
| Java | `package.Class`, or `package.Outer.Inner` | the method name |
| Go | the package import path, or `import/path.Receiver` | the function or method name |
| TypeScript | the dotted module path, or `module.Class` | the function or method name |
| Rust | `crate::module`, or `crate::module::Type` | the function or method name |
| Python | the dotted module path, or `module.Class` | the function or method name |
Rename or move is a new entry. There is no identity matching across runs.
## What each language counts
Clojure follows crap4clj: `if` / `when` and their variants, `and`, `or`, `loop`, `catch`, and each clause of `cond`, `condp`, `case`, `cond->`, `cond->>`, `some->`, and `some->>`. Coverage prefers Cloverage's per-line form counts and falls back to LCOV.
Java follows crap4java: `if`, loops, `catch`, `?:`, each `switch` label, and `&&` / `||`. Constructors and methods inside anonymous classes are omitted. Coverage is JaCoCo's `INSTRUCTION` counter.
Go follows crap4go: `if`, `for`, `range`, each `switch` and `select` clause, and `&&` / `||`. Coverage is `go test -coverprofile`.
TypeScript, TSX, and JavaScript (`.js`, `.jsx`, `.mjs`, `.cjs`) use the same structural decisions as Java, including `&&` inside JSX, plus `??` and `?.`. Top-level functions, class methods, and top-level arrow functions are entries. An inline Express callback — `.get`, `.post`, `.put`, `.patch`, `.delete`, `.head`, `.options`, `.all`, `.use`, and `.route(path).get(...)` — is its own entry, named `GET /users`. A second callback on that same route is `GET /users#2`. Its decisions are not also charged to the enclosing function. Other nested callbacks stay inside the enclosing function. Coverage is LCOV. When the report has branch records (`BRDA`) inside a function, the score uses those branches;