perf(test): reduce import and fixture overhead in hot tests

src/tui/theme/theme.test.ts

@@ -1,38 +1,54 @@
-import { describe, expect, it } from "vitest";
-import { markdownTheme } from "./theme.js";
+import { beforeEach, describe, expect, it, vi } from "vitest";
+
+const cliHighlightMocks = vi.hoisted(() => ({
+  highlight: vi.fn((code: string) => code),
+  supportsLanguage: vi.fn((_lang: string) => true),
+}));
+
+vi.mock("cli-highlight", () => cliHighlightMocks);
+
+const { markdownTheme } = await import("./theme.js");
+
+const stripAnsi = (str: string) =>
+  str.replace(new RegExp(`${String.fromCharCode(27)}\\[[0-9;]*m`, "g"), "");
 
 describe("markdownTheme", () => {
   describe("highlightCode", () => {
-    it("returns highlighted lines for common language inputs", () => {
-      const code = `const x = 42;`;
-      const js = markdownTheme.highlightCode!(code, "javascript");
-
-      expect(js).toBeInstanceOf(Array);
-      expect(js).toHaveLength(1);
-      expect(js[0]).toContain("const");
-      expect(js[0]).toContain("42");
+    beforeEach(() => {
+      cliHighlightMocks.highlight.mockReset();
+      cliHighlightMocks.supportsLanguage.mockReset();
+      cliHighlightMocks.highlight.mockImplementation((code: string) => code);
+      cliHighlightMocks.supportsLanguage.mockReturnValue(true);
     });
 
-    it("handles unknown or missing language and preserves content", () => {
-      const code = `echo "hello"`;
-      const unknown = markdownTheme.highlightCode!(code, "not-a-real-language");
-      const missing = markdownTheme.highlightCode!(code, undefined);
-      expect(unknown).toBeInstanceOf(Array);
-      expect(missing).toBeInstanceOf(Array);
-      expect(unknown).toHaveLength(1);
-      expect(missing).toHaveLength(1);
-      expect(unknown[0]).toContain("echo");
-      expect(missing[0]).toContain("echo");
-      const codeBlock = `const message = "Hello, World!";
-console.log(message);`;
-      const result = markdownTheme.highlightCode!(codeBlock, "javascript");
-      const empty = markdownTheme.highlightCode!("", "javascript");
+    it("passes supported language through to the highlighter", () => {
+      markdownTheme.highlightCode!("const x = 42;", "javascript");
+      expect(cliHighlightMocks.supportsLanguage).toHaveBeenCalledWith("javascript");
+      expect(cliHighlightMocks.highlight).toHaveBeenCalledWith(
+        "const x = 42;",
+        expect.objectContaining({ language: "javascript" }),
+      );
+    });
 
-      const stripAnsi = (str: string) =>
-        str.replace(new RegExp(`${String.fromCharCode(27)}\\[[0-9;]*m`, "g"), "");
-      expect(stripAnsi(result[0])).toBe(`const message = "Hello, World!";`);
-      expect(stripAnsi(result[1])).toBe("console.log(message);");
-      expect(empty).toEqual([""]);
+    it("falls back to auto-detect for unknown language and preserves lines", () => {
+      cliHighlightMocks.supportsLanguage.mockReturnValue(false);
+      cliHighlightMocks.highlight.mockImplementation((code: string) => `${code}\nline-2`);
+      const result = markdownTheme.highlightCode!(`echo "hello"`, "not-a-real-language");
+      expect(cliHighlightMocks.highlight).toHaveBeenCalledWith(
+        `echo "hello"`,
+        expect.objectContaining({ language: undefined }),
+      );
+      expect(stripAnsi(result[0] ?? "")).toContain("echo");
+      expect(stripAnsi(result[1] ?? "")).toBe("line-2");
+    });
+
+    it("returns plain highlighted lines when highlighting throws", () => {
+      cliHighlightMocks.highlight.mockImplementation(() => {
+        throw new Error("boom");
+      });
+      const result = markdownTheme.highlightCode!("echo hello", "javascript");
+      expect(result).toHaveLength(1);
+      expect(stripAnsi(result[0] ?? "")).toBe("echo hello");
     });
   });
 });