Function newFileDiff

actions/setup/js/apply_samples.test.cjs:265–272

* Build a unified diff that adds a brand-new file. Synthetic but realistic.

(filePath, contents)

   * Build a unified diff that adds a brand-new file. Synthetic but realistic.
   */
  function newFileDiff(filePath, contents) {
    const lines = contents.split("\n");
    // Strip trailing empty element produced by a terminating "\n" so the
    // hunk header line count matches what git apply expects.
    if (lines[lines.length - 1] === "") lines.pop();
    const body = lines.map(l => "+" + l).join("\n");
    return `diff --git a/${filePath} b/${filePath}\n` + `new file mode 100644\n` + `index 0000000..1111111\n` + `--- /dev/null\n` + `+++ b/${filePath}\n` + `@@ -0,0 +1,${lines.length} @@\n` + body + "\n";
  }

  it("checks out the requested branch and commits the patch on it (create_pull_request)", async () => {
    const workspace = makeTempDir("gh-aw-prestage-cpr-");