feat: 搭建单元测试基础设施 — Bun test runner + 示例测试

添加 bunfig.toml 配置、test script，以及三组示例测试：
- src/utils/array.ts (intersperse, count, uniq)
- src/utils/set.ts (difference, intersects, every, union)
- packages/color-diff-napi (ansi256FromRgb, colorToEscape, detectLanguage 等)

41 tests, 0 failures.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

packages/color-diff-napi/src/__tests__/color-diff.test.ts

@@ -0,0 +1,102 @@
+import { describe, expect, test } from "bun:test";
+import { __test } from "../index";
+
+const { ansi256FromRgb, colorToEscape, detectColorMode, detectLanguage, tokenize } = __test;
+
+describe("ansi256FromRgb", () => {
+	test("black maps to index 16", () => {
+		expect(ansi256FromRgb(0, 0, 0)).toBe(16);
+	});
+
+	test("pure red maps to cube red", () => {
+		expect(ansi256FromRgb(255, 0, 0)).toBe(196);
+	});
+
+	test("pure green maps to cube green", () => {
+		expect(ansi256FromRgb(0, 255, 0)).toBe(46);
+	});
+
+	test("pure blue maps to cube blue", () => {
+		expect(ansi256FromRgb(0, 0, 255)).toBe(21);
+	});
+
+	test("grey values map to grey ramp", () => {
+		const idx = ansi256FromRgb(128, 128, 128);
+		// Should be in the grey ramp range (232-255)
+		expect(idx).toBeGreaterThanOrEqual(232);
+		expect(idx).toBeLessThanOrEqual(255);
+	});
+});
+
+describe("colorToEscape", () => {
+	test("palette index < 8 uses standard ANSI codes", () => {
+		const color = { r: 1, g: 0, b: 0, a: 0 }; // palette index 1
+		expect(colorToEscape(color, true, "truecolor")).toBe("\x1b[31m"); // fg red
+		expect(colorToEscape(color, false, "truecolor")).toBe("\x1b[41m"); // bg red
+	});
+
+	test("palette index 8-15 uses bright ANSI codes", () => {
+		const color = { r: 9, g: 0, b: 0, a: 0 }; // bright red
+		expect(colorToEscape(color, true, "truecolor")).toBe("\x1b[91m");
+	});
+
+	test("alpha=1 returns terminal default", () => {
+		const color = { r: 0, g: 0, b: 0, a: 1 };
+		expect(colorToEscape(color, true, "truecolor")).toBe("\x1b[39m");
+		expect(colorToEscape(color, false, "truecolor")).toBe("\x1b[49m");
+	});
+
+	test("truecolor uses RGB escape", () => {
+		const color = { r: 100, g: 150, b: 200, a: 255 };
+		expect(colorToEscape(color, true, "truecolor")).toBe("\x1b[38;2;100;150;200m");
+	});
+
+	test("color256 uses 256-color escape", () => {
+		const color = { r: 100, g: 150, b: 200, a: 255 };
+		const result = colorToEscape(color, true, "color256");
+		expect(result).toMatch(/^\x1b\[38;5;\d+m$/);
+	});
+});
+
+describe("detectColorMode", () => {
+	test("returns ansi for ansi-containing theme names", () => {
+		expect(detectColorMode("ansi")).toBe("ansi");
+		expect(detectColorMode("base16-ansi-dark")).toBe("ansi");
+	});
+
+	test("returns truecolor or color256 for non-ansi themes", () => {
+		const mode = detectColorMode("monokai");
+		expect(["truecolor", "color256"]).toContain(mode);
+	});
+});
+
+describe("detectLanguage", () => {
+	test("detects language from file extension", () => {
+		expect(detectLanguage("index.ts")).toBe("ts");
+		expect(detectLanguage("main.py")).toBe("py");
+		expect(detectLanguage("style.css")).toBe("css");
+	});
+
+	test("detects language from known filenames", () => {
+		expect(detectLanguage("Makefile")).toBe("makefile");
+		expect(detectLanguage("Dockerfile")).toBe("dockerfile");
+	});
+
+	test("returns null for unknown extensions", () => {
+		expect(detectLanguage("file.xyz123")).toBeNull();
+	});
+});
+
+describe("tokenize", () => {
+	test("returns array of tokens", () => {
+		const result = tokenize("hello world");
+		expect(Array.isArray(result)).toBe(true);
+		expect(result.length).toBeGreaterThan(0);
+	});
+
+	test("preserves original text when joined", () => {
+		const text = "foo bar baz";
+		const tokens = tokenize(text);
+		expect(tokens.join("")).toBe(text);
+	});
+});