show code diff locally

Author: msyyc

.gitignore

@@ -225,3 +225,4 @@ packages/samples/test/output/azure/templates-contoso/setup.*
 # python emitter
 packages/typespec-python/tests/generated/**
 packages/typespec-python/alpha
+.python-code-diff

packages/typespec-python/eng/scripts/show-diff.ts

@@ -0,0 +1,87 @@
+/* eslint-disable no-console */
+/**
+ * Build a side-by-side diff workspace comparing the locally generated Python
+ * SDKs against the committed baseline in the azure-sdk-for-python repo.
+ *
+ * Steps:
+ *   1. (Re)create `<repo-root>/.python-code-diff`, clearing any existing content.
+ *   2. Sparse-checkout `eng/tools/azure-sdk-tools/emitter/generated` from the
+ *      `typespec-python-generated-tests` branch of Azure/azure-sdk-for-python.
+ *   3. Remove the checked-out `azure` and `unbranded` baselines.
+ *   4. Copy this package's freshly generated `tests/generated/azure` and
+ *      `tests/generated/unbranded` into their place.
+ *   5. Open the diff folder in VS Code (or print its path if `code` is missing).
+ *
+ * Usage:
+ *   tsx eng/scripts/show-diff.ts
+ */
+import { execSync } from "child_process";
+import { cpSync, existsSync, rmSync } from "fs";
+import { dirname, join } from "path";
+import pc from "picocolors";
+import { fileURLToPath } from "url";
+
+const here = dirname(fileURLToPath(import.meta.url));
+// eng/scripts/show-diff.ts -> package root is two levels up
+const packageRoot = join(here, "..", "..");
+// packageRoot == <repo-root>/packages/typespec-python, so the repo root is two
+// levels up from packageRoot.
+const repoRoot = join(packageRoot, "..", "..");
+
+const REPO_URL = "https://github.com/Azure/azure-sdk-for-python.git";
+const BRANCH = "typespec-python-generated-tests";
+const SPARSE_PATH = "eng/tools/azure-sdk-tools/emitter/generated";
+
+const diffDir = join(repoRoot, ".python-code-diff");
+const generatedDir = join(diffDir, ...SPARSE_PATH.split("/"));
+
+const flavors = ["azure", "unbranded"] as const;
+
+function run(command: string, cwd: string): void {
+  console.log(pc.gray(`$ ${command}`));
+  execSync(command, { cwd, stdio: "inherit" });
+}
+
+// 1. (Re)create the diff folder, clearing any existing content.
+if (existsSync(diffDir)) {
+  console.log(pc.yellow(`Clearing existing ${diffDir}`));
+  rmSync(diffDir, { recursive: true, force: true });
+}
+
+// 2. Sparse-checkout the baseline generated folder.
+console.log(pc.cyan(`Cloning ${REPO_URL} (${BRANCH})...`));
+run(
+  `git clone --no-checkout --depth 1 --filter=blob:none --branch ${BRANCH} ${REPO_URL} "${diffDir}"`,
+  repoRoot,
+);
+run("git sparse-checkout init --cone", diffDir);
+run(`git sparse-checkout set ${SPARSE_PATH}`, diffDir);
+run("git checkout", diffDir);
+
+// 3. Remove the checked-out azure / unbranded baselines.
+for (const flavor of flavors) {
+  const target = join(generatedDir, flavor);
+  if (existsSync(target)) {
+    console.log(pc.yellow(`Removing baseline ${target}`));
+    rmSync(target, { recursive: true, force: true });
+  }
+}
+
+// 4. Copy locally generated azure / unbranded into place.
+for (const flavor of flavors) {
+  const source = join(packageRoot, "tests", "generated", flavor);
+  const target = join(generatedDir, flavor);
+  if (!existsSync(source)) {
+    console.warn(pc.yellow(`Skipping ${flavor}: ${source} does not exist`));
+    continue;
+  }
+  console.log(pc.cyan(`Copying ${source} -> ${target}`));
+  cpSync(source, target, { recursive: true });
+}
+
+// 5. Open the diff folder in VS Code, or print its path on failure.
+try {
+  execSync(`code "${diffDir}"`, { stdio: "inherit" });
+} catch {
+  console.log(pc.green(`see code diff in ${diffDir}`));
+}

packages/typespec-python/package.json

@@ -39,6 +39,7 @@
     "format:extra:check": "tsx ./eng/scripts/ci/format.ts --python --check",
     "regenerate": "tsx ./eng/scripts/ci/regenerate.ts",
     "sync": "tsx ./eng/scripts/sync.ts",
+    "show-diff": "pnpm regenerate && tsx ./eng/scripts/show-diff.ts",
     "sync:check": "tsx ./eng/scripts/sync.ts --check",
     "test:python:e2e": "tsx ./eng/scripts/ci/run-tests.ts",
     "regen-docs": "pnpm run build && tspd doc . --enable-experimental --output-dir ./website/src/content/docs/docs/emitters/clients/typespec-python/reference --skip-js"