test(docs-infra): add commands to run the unit tests (angular#34537)

This commit adds the necessary custom commands to run the tests in a
node environment.

PR Close angular#34537

aio/content/examples/comparing-observables/e2e/src/app.e2e-spec.ts

@@ -0,0 +1,9 @@
+/*
+ * This example project is special in that it is not a cli app. To run tests appropriate for this
+ * project, the test command is overwritten in `aio/content/examples/observables/example-config.json`.
+ *
+ * This is an empty placeholder file to ensure that `aio/tools/examples/run-example-e2e.js` runs
+ * tests for this project.
+ *
+ * TODO: Fix our infrastructure/tooling, so that this hack is not necessary.
+ */

aio/content/examples/comparing-observables/example-config.json

@@ -0,0 +1,12 @@
+{
+  "tests": [
+    {
+      "cmd": "yarn",
+      "args": ["tsc", "--project", "tsconfig.spec.json", "--module", "commonjs"]
+    },
+    {
+      "cmd": "yarn",
+      "args": ["jasmine", "out-tsc/**/*.spec.js"]
+    }
+  ]
+}