docs: add instructions for authenticating for system tests (#494)

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Source-Link: googleapis/synthtool@363fe30

packages/google-cloud-tasks/CONTRIBUTING.md

@@ -37,6 +37,15 @@ accept your pull requests.
 1. Title your pull request following [Conventional Commits](https://www.conventionalcommits.org/) styling.
 1. Submit a pull request.
 
+### Before you begin
+
+1. [Select or create a Cloud Platform project][projects].
+1. [Enable billing for your project][billing]. 
+1. [Enable the Cloud Tasks API][enable_api]. 
+1. [Set up authentication with a service account][auth] so you can access the
+ API from your local workstation.
+
+
 ## Running the tests
 
 1. [Prepare your environment for Node.js setup][setup].
@@ -51,15 +60,17 @@ accept your pull requests.
  npm test
 
  # Run sample integration tests.
- gcloud auth application-default login
  npm run samples-test
 
  # Run all system tests.
- gcloud auth application-default login
  npm run system-test
 
 1. Lint (and maybe fix) any changes:
 
  npm run fix
 
 [setup]: https://cloud.google.com/nodejs/docs/setup
+[projects]: https://console.cloud.google.com/project
+[billing]: https://support.google.com/cloud/answer/6293499#enable-billing
+[enable_api]: https://console.cloud.google.com/flows/enableapi?apiid=tasks.googleapis.com
+[auth]: https://cloud.google.com/docs/authentication/getting-started

packages/google-cloud-tasks/README.md

@@ -111,8 +111,7 @@ quickstart();
 
 ## Samples
 
-Samples are in the [`samples/`](https://github.com/googleapis/nodejs-tasks/tree/master/samples) directory. The samples' `README.md`
-has instructions for running the samples.
+Samples are in the [`samples/`](https://github.com/googleapis/nodejs-tasks/tree/master/samples) directory. Each sample's `README.md` has instructions for running its sample.
 
 | Sample | Source Code | Try it |
 | --------------------------- | --------------------------------- | ------ |

packages/google-cloud-tasks/synth.metadata

@@ -4,7 +4,7 @@
  "git": {
  "name": ".",
  "remote": "https://github.com/googleapis/nodejs-tasks.git",
- "sha": "5590c731d91e609f75dac2304b9ce3e4d960e5fd"
+ "sha": "81c4b4ece21eb99cec582d3256192de6c402d771"
  }
  },
  {
@@ -19,7 +19,7 @@
  "git": {
  "name": "synthtool",
  "remote": "https://github.com/googleapis/synthtool.git",
- "sha": "15013eff642a7e7e855aed5a29e6e83c39beba2a"
+ "sha": "363fe305e9ce34a6cd53951c6ee5f997094b54ee"
  }
  }
  ],