build: generate a new app in ng new test (#27062)

Currently the `ng new` integration test uses a pre-generated app which we need to keep up to date. This can cause us to miss changes in the project structure between CLI versions.

These changes switch to generating the project on-the-fly and adding Material to it instead.

I've only done this for the standalone test to verify the approach, but it should be applied to the `ng add` test as well.

Author: crisbeto

integration/ng-add-standalone/.editorconfig

@@ -10,6 +10,9 @@ npmPackageMappings = dicts.add(
     },
 )
 
+# Name of the generated app.
+APP_NAME = "ng-add-standalone"
+
 node_integration_test(
     name = "test",
     srcs = glob(["**/*"]),
@@ -19,6 +22,22 @@ node_integration_test(
         # See: https://github.com/yarnpkg/yarn/issues/2165.
         # TODO(devversion): determine if a solution/workaround could live in the test runner.
         "yarn install --cache-folder .yarn_cache_folder/",
+
+        # Generate a new standalone project with the default options.
+        # Skip installation since we installed the dependencies already.
+        "yarn ng new --defaults --standalone --skip-install --style=scss --name=%s" % APP_NAME,
+        # Delete the package.json that the CLI generated since we want to use the existing one.
+        "rm -f %s/package.json" % APP_NAME,
+        # Delete the Karma config since we need to use a headless browser.
+        "rm -f %s/karma.conf.js" % APP_NAME,
+        # We can't name the checked-in config `angular.json`, because the CLI doesn't allow
+        # `ng new` to run in a directory that has an `angular.json` already.
+        "mv _angular.json angular.json",
+        # Delete the angular.json since we have a specific config for the test.
+        "rm -f %s/angular.json" % APP_NAME,
+        # Move the generated project one level up so it can reuse the package.json and node_modules.
+        "mv %s/* ." % APP_NAME,
+        # Install Material and run the unit tests.
         "yarn ng add @angular/material",
         "yarn test",
     ],