test: add snapshot test for license file generation

Adds a characterization test that verifies THIRD-PARTY-LICENSES.md output
using a snapshot, ensuring behavioral equivalence when replacing the
license collection implementation.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

Author: naitokosuke

test/__snapshots__/obuild.test.ts.snap

@@ -0,0 +1,38 @@
+// Vitest Snapshot v1, https://vitest.dev/guide/snapshot.html
+
+exports[`obuild > license file matches snapshot 1`] = `
+"# Licenses of Bundled Dependencies
+
+The published artifact additionally contains code with the following licenses:
+MIT
+
+# Bundled Dependencies
+
+## defu
+
+License: MIT
+Repository: https://github.com/unjs/defu
+
+> MIT License
+> 
+> Copyright (c) Pooya Parsa <pooya@pi0.io>
+> 
+> Permission is hereby granted, free of charge, to any person obtaining a copy
+> of this software and associated documentation files (the "Software"), to deal
+> in the Software without restriction, including without limitation the rights
+> to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+> copies of the Software, and to permit persons to whom the Software is
+> furnished to do so, subject to the following conditions:
+> 
+> The above copyright notice and this permission notice shall be included in all
+> copies or substantial portions of the Software.
+> 
+> THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+> IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+> FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+> AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+> LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+> OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+> SOFTWARE.
+"
+`;

test/obuild.test.ts

@@ -76,18 +76,8 @@ describe("obuild", () => {
     expect(stats.mode & 0o111).toBe(0o111); // Check if executable
   });
 
-  test("license file is generated with correct structure", async () => {
+  test("license file matches snapshot", async () => {
     const content = await readFile(new URL("THIRD-PARTY-LICENSES.md", distDir), "utf8");
-    expect(content).toContain("# Licenses of Bundled Dependencies");
-    expect(content).toContain("# Bundled Dependencies");
-    expect(content).toContain("MIT");
-  });
-
-  test("license file contains bundled dependency info", async () => {
-    const content = await readFile(new URL("THIRD-PARTY-LICENSES.md", distDir), "utf8");
-    expect(content).toContain("## defu");
-    expect(content).toContain("License: MIT");
-    expect(content).toContain("Pooya Parsa");
-    expect(content).toContain("> MIT License");
+    expect(content).toMatchSnapshot();
   });
 });