Testing

Test Suites

All tests live under src/test/suite/ and use Mocha in TDD mode (suite / test).

File	Kind	What it covers
`type-analyzer.test.ts`	Unit	Monomorphic/polymorphic detection, edge cases
`code-generator.test.ts`	Unit	Wrapper generation, port annotations, DiffClock handling
`manifest-frequency.test.ts`	Unit	Which clock domain sets the P&R target frequency
`diagram-tabs.test.ts`	Unit	Diagrams reuse one preview tab; pinned ones are kept
`gitignore.test.ts`	Unit	When the `.clash/` gitignore offer is made and what it writes
`run-history.test.ts`	Unit	Reading past runs off disk; which directories count as history
`contributions.test.ts`	Unit	package.json contributions match what the extension registers
`synthesis-features.test.ts`	Unit	Commands, configuration, synthesis types
`synthesis-targets.test.ts`	Unit	Target registry, default/resolved scripts, script diffing, and that the installed Yosys supports every offered target
`parallelism.test.ts`	Unit	Job-count resolution shared by the cabal/GHC/Yosys/nextpnr `*Jobs` settings
`settings-panel.test.ts`	Unit	The settings panel’s embedded webview script parses and its custom-script keys resolve
`code-actions.test.ts`	Unit	Code action provider for Haskell functions
`platform-tools.test.ts`	Unit	Yosys/nextpnr tool detection
`tool-provider.test.ts`	Unit	Managed toolchain resolution and install paths
`toolchain.test.ts`	Unit	Full toolchain availability
`clash-compiler.test.ts`	Unit	Clash compiler invocation helpers
`nextpnr-runner.test.ts`	Unit	nextpnr child-process lifecycle
`results-tree.test.ts`	Unit	Results tree construction
`clash-tree.test.ts`	Unit	Sidebar sections and routing to their providers
`functions-tree.test.ts`	Unit	The Functions section’s empty states: HLS missing, working, or done
`internal-components.test.ts`	Unit	Internal component expansion
`netlist-renderer.test.ts`	Unit	netlistsvg-based diagram rendering
`packaging.test.ts`	Unit	What `vsce` would package: deny list, required files
`spawn-options.test.ts`	Unit	Every external-tool spawn passes `windowsHide`, so no console window flashes on Windows
`pnr-targets.test.ts`	Integration	End-to-end synthesis + place & route per target
`ooc-blackbox.test.ts`	Integration	Out-of-context scripts stub sub-components as black boxes; a real Yosys run proves they survive
`hls-client.test.ts`	Integration	HLS communication
`function-detector.test.ts`	Integration	Function detection from real Haskell files via HLS
`integration.test.ts`	Integration	Per-module synthesis, target frequency, end-to-end flows

Running Tests

From the terminal

npm test

This compiles first (via pretest) and then launches a headless VS Code instance against test-project/.

runTest.ts handles the two environment problems that used to make this fail:

NixOS / headless hosts. Set VSCODE_EXECUTABLE_PATH to a nix-wrapped Electron binary (e.g. from vscode-fhs) if the downloaded VS Code build cannot find its system libraries. Leave it unset to let @vscode/test-electron download a matching build. It must be a real Electron binary, not the code CLI wrapper — the wrapper backgrounds the app and exits 0, so the test host never runs.
Running from VS Code’s integrated terminal. The parent editor leaks ELECTRON_RUN_AS_NODE=1 and a set of VSCODE_* variables that would make the test host run as plain Node or attach to the running instance. runTest.ts strips them, so the integrated terminal works the same as an external one.

From VS Code

Ctrl+Shift+D → select Extension Tests
Press F5

A second VS Code window opens with the test-project workspace, runs all suites, and reports results in the Debug Console. Use this when you want breakpoints.

Writing a New Test

import * as assert from 'assert';

suite('My Feature', () => {
    test('does the right thing', () => {
        assert.strictEqual(1 + 1, 2);
    });

    test('async operation', async function () {
        this.timeout(10_000);
        const result = await someAsyncCall();
        assert.ok(result);
    });
});

Place the file in src/test/suite/ with a .test.ts suffix — the test runner picks it up automatically via the glob in index.ts.

Debugging a Test

Set breakpoints in your .test.ts file, then launch Extension Tests with F5. Execution pauses at breakpoints; use the Debug panel to inspect state.

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