test: extract computeWordClass tests to dedicated file

- Move computeWordClass tests from subtitle-render.test.ts to subtitle-render-word-class.test.ts
- Extract createToken helper into subtitle-render-test-helpers.ts for reuse
- Register new test file in test:core:src and test:core:dist scripts

src/renderer/subtitle-render-word-class.test.ts

@@ -0,0 +1,206 @@
+import test from 'node:test';
+import assert from 'node:assert/strict';
+
+import type { MergedToken } from '../types';
+import { computeWordClass } from './subtitle-render.js';
+import { createToken } from './subtitle-render-test-helpers.js';
+
+test('computeWordClass preserves known and n+1 classes while adding JLPT classes', () => {
+  const knownJlpt = createToken({
+    isKnown: true,
+    jlptLevel: 'N1',
+    surface: '猫',
+  });
+  const nPlusOneJlpt = createToken({
+    isNPlusOneTarget: true,
+    jlptLevel: 'N2',
+    surface: '犬',
+  });
+
+  assert.equal(computeWordClass(knownJlpt), 'word word-known word-jlpt-n1');
+  assert.equal(computeWordClass(nPlusOneJlpt), 'word word-n-plus-one word-jlpt-n2');
+});
+
+test('computeWordClass applies name-match class ahead of known, n+1, frequency, and JLPT classes when enabled', () => {
+  const token = createToken({
+    isKnown: true,
+    isNPlusOneTarget: true,
+    jlptLevel: 'N2',
+    frequencyRank: 10,
+    surface: 'アクア',
+  }) as MergedToken & { isNameMatch?: boolean };
+  token.isNameMatch = true;
+
+  assert.equal(
+    computeWordClass(token, {
+      nameMatchEnabled: true,
+      enabled: true,
+      topX: 100,
+      mode: 'single',
+      singleColor: '#000000',
+      bandedColors: ['#000000', '#000000', '#000000', '#000000', '#000000'] as const,
+    }),
+    'word word-name-match',
+  );
+});
+
+test('computeWordClass skips name-match class by default', () => {
+  const token = createToken({
+    surface: 'アクア',
+  }) as MergedToken & { isNameMatch?: boolean };
+  token.isNameMatch = true;
+
+  assert.equal(computeWordClass(token), 'word');
+});
+
+test('computeWordClass skips name-match class when disabled', () => {
+  const token = createToken({
+    surface: 'アクア',
+  }) as MergedToken & { isNameMatch?: boolean };
+  token.isNameMatch = true;
+
+  assert.equal(
+    computeWordClass(token, {
+      nameMatchEnabled: false,
+      enabled: true,
+      topX: 100,
+      mode: 'single',
+      singleColor: '#000000',
+      bandedColors: ['#000000', '#000000', '#000000', '#000000', '#000000'] as const,
+    }),
+    'word',
+  );
+});
+
+test('computeWordClass keeps known and N+1 color classes exclusive over frequency classes', () => {
+  const known = createToken({
+    isKnown: true,
+    frequencyRank: 10,
+    surface: '既知',
+  });
+  const nPlusOne = createToken({
+    isNPlusOneTarget: true,
+    frequencyRank: 10,
+    surface: '目標',
+  });
+  const frequency = createToken({
+    frequencyRank: 10,
+    surface: '頻度',
+  });
+
+  assert.equal(
+    computeWordClass(known, {
+      enabled: true,
+      topX: 100,
+      mode: 'single',
+      singleColor: '#000000',
+      bandedColors: ['#000000', '#000000', '#000000', '#000000', '#000000'] as const,
+    }),
+    'word word-known',
+  );
+  assert.equal(
+    computeWordClass(nPlusOne, {
+      enabled: true,
+      topX: 100,
+      mode: 'single',
+      singleColor: '#000000',
+      bandedColors: ['#000000', '#000000', '#000000', '#000000', '#000000'] as const,
+    }),
+    'word word-n-plus-one',
+  );
+  assert.equal(
+    computeWordClass(frequency, {
+      enabled: true,
+      topX: 100,
+      mode: 'single',
+      singleColor: '#000000',
+      bandedColors: ['#000000', '#000000', '#000000', '#000000', '#000000'] as const,
+    }),
+    'word word-frequency-single',
+  );
+});
+
+test('computeWordClass adds frequency class for single mode when rank is within topX', () => {
+  const token = createToken({
+    surface: '猫',
+    frequencyRank: 50,
+  });
+
+  const actual = computeWordClass(token, {
+    enabled: true,
+    topX: 100,
+    mode: 'single',
+    singleColor: '#000000',
+    bandedColors: ['#000000', '#000000', '#000000', '#000000', '#000000'] as const,
+  });
+
+  assert.equal(actual, 'word word-frequency-single');
+});
+
+test('computeWordClass adds frequency class when rank equals topX', () => {
+  const token = createToken({
+    surface: '水',
+    frequencyRank: 100,
+  });
+
+  const actual = computeWordClass(token, {
+    enabled: true,
+    topX: 100,
+    mode: 'single',
+    singleColor: '#000000',
+    bandedColors: ['#000000', '#000000', '#000000', '#000000', '#000000'] as const,
+  });
+
+  assert.equal(actual, 'word word-frequency-single');
+});
+
+test('computeWordClass adds frequency class for banded mode', () => {
+  const token = createToken({
+    surface: '犬',
+    frequencyRank: 250,
+  });
+
+  const actual = computeWordClass(token, {
+    enabled: true,
+    topX: 1000,
+    mode: 'banded',
+    singleColor: '#000000',
+    bandedColors: ['#111111', '#222222', '#333333', '#444444', '#555555'] as const,
+  });
+
+  assert.equal(actual, 'word word-frequency-band-2');
+});
+
+test('computeWordClass uses configured band count for banded mode', () => {
+  const token = createToken({
+    surface: '犬',
+    frequencyRank: 2,
+  });
+
+  const actual = computeWordClass(token, {
+    enabled: true,
+    topX: 4,
+    mode: 'banded',
+    singleColor: '#000000',
+    bandedColors: ['#111111', '#222222', '#333333', '#444444', '#555555'],
+  } as any);
+
+  assert.equal(actual, 'word word-frequency-band-3');
+});
+
+test('computeWordClass skips frequency class when rank is out of topX', () => {
+  const token = createToken({
+    surface: '犬',
+    frequencyRank: 1200,
+  });
+
+  const actual = computeWordClass(token, {
+    enabled: true,
+    topX: 1000,
+    mode: 'single',
+    singleColor: '#000000',
+    bandedColors: ['#000000', '#000000', '#000000', '#000000', '#000000'] as const,
+  });
+
+  assert.equal(actual, 'word');
+});