Fix monorepo build args split and add test for getBuildOptions (#376)

Currently in the buildpack our build args are joined together using "," instead of ".",  so MONOREPO_BUILD_ARGS should split by commas.

Author: sjjj986

packages/@apphosting/common/src/index.spec.ts

@@ -2,7 +2,56 @@ import assert from "assert";
 import fs from "fs";
 import path from "path";
 import os from "os";
-import { updateOrCreateGitignore } from "./index";
+import { getBuildOptions, updateOrCreateGitignore } from "./index";
+
+const originalCwd = process.cwd.bind(process);
+
+describe("get a set of build options", () => {
+  const mockCwd = "/fake/project/";
+  beforeEach(() => {
+    process.cwd = () => mockCwd;
+  });
+
+  afterEach(() => {
+    process.cwd = originalCwd;
+    delete process.env.MONOREPO_COMMAND;
+    delete process.env.MONOREPO_BUILD_ARGS;
+    delete process.env.GOOGLE_BUILDABLE;
+    delete process.env.MONOREPO_PROJECT;
+  });
+
+  it("returns monorepo build options when MONOREPO_COMMAND is set", () => {
+    process.env.MONOREPO_COMMAND = "turbo";
+    process.env.MONOREPO_BUILD_ARGS = "--filter=web,--env-mode=strict";
+    process.env.GOOGLE_BUILDABLE = "/workspace/apps/web";
+    process.env.MONOREPO_PROJECT = "web";
+
+    const expectedOptions = {
+      buildCommand: "turbo",
+      buildArgs: ["run", "build", "--filter=web", "--env-mode=strict"],
+      projectDirectory: "/workspace/apps/web",
+      projectName: "web",
+    };
+    assert.deepStrictEqual(
+      getBuildOptions(),
+      expectedOptions,
+      "Monorepo build options are incorrect",
+    );
+  });
+
+  it("returns standard build options when MONOREPO_COMMAND is not set", () => {
+    const expectedOptions = {
+      buildCommand: "npm",
+      buildArgs: ["run", "build"],
+      projectDirectory: process.cwd(),
+    };
+    assert.deepStrictEqual(
+      getBuildOptions(),
+      expectedOptions,
+      "Standard build options are incorrect",
+    );
+  });
+});
 
 describe("update or create .gitignore", () => {
   let tmpDir: string;

packages/@apphosting/common/src/index.ts

@@ -130,7 +130,7 @@ export function getBuildOptions(): BuildOptions {
   if (process.env.MONOREPO_COMMAND) {
     return {
       buildCommand: process.env.MONOREPO_COMMAND,
-      buildArgs: ["run", "build"].concat(process.env.MONOREPO_BUILD_ARGS?.split(".") || []),
+      buildArgs: ["run", "build"].concat(process.env.MONOREPO_BUILD_ARGS?.split(",") || []),
       projectDirectory: process.env.GOOGLE_BUILDABLE || "",
       projectName: process.env.MONOREPO_PROJECT,
     };