pi-mono/packages/coding-agent/test/syntax-highlight.test.ts

import { resetCapabilitiesCache, setCapabilities } from "@earendil-works/pi-tui";
import { afterEach, beforeEach, describe, expect, it } from "vitest";
import {
	getLanguageFromPath,
	getMarkdownTheme,
	highlightCode,
	initTheme,
	theme,
} from "../src/modes/interactive/theme/theme.ts";
import {
	highlight,
	loadAllHighlightLanguages,
	renderHighlightedHtml,
	supportsLanguage,
} from "../src/utils/syntax-highlight.ts";

const eagerLanguages = [
	"python",
	"java",
	"go",
	"javascript",
	"cpp",
	"typescript",
	"php",
	"ruby",
	"c",
	"csharp",
	"nix",
	"bash",
	"rust",
	"scala",
	"kotlin",
	"swift",
	"dart",
	"groovy",
	"perl",
	"lua",
];
const eagerLanguagesLoadedAtStartup = eagerLanguages.every(supportsLanguage);
const uncommonLanguageLoadedAtStartup = supportsLanguage("ada");

describe("syntax highlight renderer", () => {
	it("loads the twenty most common languages at startup and defers the rest", async () => {
		expect(eagerLanguagesLoadedAtStartup).toBe(true);
		expect(uncommonLanguageLoadedAtStartup).toBe(false);
		await loadAllHighlightLanguages();
		expect(supportsLanguage("ada")).toBe(true);
	});

	it("maps file extensions of eagerly loaded languages to their language", () => {
		expect(getLanguageFromPath("lib/main.dart")).toBe("dart");
		expect(getLanguageFromPath("flake.nix")).toBe("nix");
		expect(getLanguageFromPath("script.groovy")).toBe("groovy");
		expect(getLanguageFromPath("build.gradle")).toBe("groovy");
		expect(getLanguageFromPath("src/Main.kt")).toBe("kotlin");
	});

	it("renders highlighted spans with the provided theme", () => {
		const rendered = renderHighlightedHtml('<span class="hljs-keyword">const</span> value', {
			keyword: (text) => `[keyword:${text}]`,
		});
		expect(rendered).toBe("[keyword:const] value");
	});

	it("decodes HTML entities emitted by highlight.js", () => {
		const rendered = renderHighlightedHtml("&lt;tag attr=&quot;value&quot;&gt;&amp;#x41;&#65;&lt;/tag&gt;");
		expect(rendered).toBe('<tag attr="value">&#x41;A</tag>');
	});

	it("inherits parent formatting for unmapped nested scopes", () => {
		const interpolation = "$" + "{x}";
		const rendered = renderHighlightedHtml(
			`<span class="hljs-string">a<span class="hljs-subst">${interpolation}</span>b</span>`,
			{
				string: (text) => `[string:${text}]`,
			},
		);
		expect(rendered).toBe(`[string:a][string:${interpolation}][string:b]`);
	});

	it("keeps parent formatting across unscoped nested spans", () => {
		const rendered = renderHighlightedHtml('<span class="hljs-string">a<span class="language-xml">b</span>c</span>', {
			string: (text) => `[string:${text}]`,
		});
		expect(rendered).toBe("[string:a][string:b][string:c]");
	});

	it("highlights code through highlight.js", () => {
		expect(supportsLanguage("typescript")).toBe(true);
		const rendered = highlight("const value = 1", {
			language: "typescript",
			ignoreIllegals: true,
			theme: {
				keyword: (text) => `[keyword:${text}]`,
				number: (text) => `[number:${text}]`,
			},
		});
		expect(rendered).toContain("[keyword:const]");
		expect(rendered).toContain("[number:1]");
	});
});

describe("theme syntax highlighting", () => {
	beforeEach(() => {
		setCapabilities({ images: null, trueColor: true, hyperlinks: false });
		initTheme("dark");
	});

	afterEach(() => {
		resetCapabilitiesCache();
	});

	// #10143
	it("colors each line of Python docstrings independently", () => {
		const code = '"""\nline one\n\nline two\n"""\nafter';
		const ansi = theme.getFgAnsi("syntaxString");
		const expected = [
			`${ansi}"""\x1b[39m`,
			`${ansi}line one\x1b[39m`,
			"",
			`${ansi}line two\x1b[39m`,
			`${ansi}"""\x1b[39m`,
			"after",
		];

		expect(highlightCode(code, "python")).toEqual(expected);
		expect(getMarkdownTheme().highlightCode?.(code, "python")).toEqual(expected);
	});

	it("colors diff additions and deletions in fenced diff blocks", () => {
		const lines = highlightCode("-old\n+new\n", "diff");

		expect(lines[0]).toBe(`${theme.getFgAnsi("toolDiffRemoved")}-old\x1b[39m`);
		expect(lines[1]).toBe(`${theme.getFgAnsi("toolDiffAdded")}+new\x1b[39m`);
	});

	it("keeps cli-highlight default styled scopes mapped to theme styles", () => {
		expect(highlightCode("const re = /foo+/gi;", "javascript")[0]).toContain(
			`${theme.getFgAnsi("syntaxString")}/foo+/gi\x1b[39m`,
		);
		expect(highlightCode("@decorator", "python")[0]).toBe(`${theme.getFgAnsi("muted")}@decorator\x1b[39m`);
		expect(highlightCode("<div></div>", "html")[0]).toContain(`${theme.getFgAnsi("syntaxKeyword")}div\x1b[39m`);
	});
});