refactor(chart): enforce 400-line source limit

scripts/check-file-length.test.ts

@@ -0,0 +1,56 @@
+import { mkdtempSync, rmSync, writeFileSync } from 'node:fs'
+import { tmpdir } from 'node:os'
+import { join } from 'node:path'
+import { afterEach, describe, expect, it } from 'vitest'
+
+import {
+  collectTextFiles,
+  findFileLengthViolations,
+  physicalLineCount,
+} from './check-file-length.mjs'
+
+const temporaryDirectories: string[] = []
+
+function makeTemporaryDirectory() {
+  const directory = mkdtempSync(join(tmpdir(), 'waveform-file-length-'))
+  temporaryDirectories.push(directory)
+  return directory
+}
+
+afterEach(() => {
+  temporaryDirectories.splice(0).forEach((directory) => {
+    rmSync(directory, { recursive: true, force: true })
+  })
+})
+
+describe('file length check', () => {
+  it('counts physical lines with and without a trailing newline', () => {
+    expect(physicalLineCount('')).toBe(0)
+    expect(physicalLineCount('first')).toBe(1)
+    expect(physicalLineCount('first\nsecond')).toBe(2)
+    expect(physicalLineCount('first\nsecond\n')).toBe(2)
+  })
+
+  it('checks text files regardless of extension and skips binary files', () => {
+    const directory = makeTemporaryDirectory()
+    writeFileSync(join(directory, 'source.custom'), 'first\nsecond')
+    writeFileSync(join(directory, 'binary.data'), Buffer.from([0, 1, 2, 3]))
+
+    expect(collectTextFiles(directory).map(({ path }) => path)).toEqual([
+      join(directory, 'source.custom'),
+    ])
+  })
+
+  it('reports the file, actual line count, and configured limit', () => {
+    const directory = makeTemporaryDirectory()
+    writeFileSync(join(directory, 'too-long.unknown'), 'first\nsecond\nthird')
+
+    expect(findFileLengthViolations(directory, 2)).toEqual([
+      {
+        path: expect.stringContaining('too-long.unknown'),
+        lineCount: 3,
+        limit: 2,
+      },
+    ])
+  })
+})