Wuandy/readme.md (#453)

Add more instructions to firestore/README.md, including how to build/test/integration test Firestore, and how to build a local maven release with latest firestore (and also latest dependencies).

Author: Hui-Wu

firebase-firestore/README.md

@@ -10,12 +10,84 @@ responsive apps that work regardless of network latency or Internet
 connectivity. Cloud Firestore also offers seamless integration with other
 Firebase and Google Cloud Platform products, including Cloud Functions.
 
+## Building
+
 All Gradle commands should be run from the source root (which is one level up
 from this folder). See the README.md in the source root for instructions on
 publishing/testing Cloud Firestore.
 
-## Testing
+To build Cloud Firestore, from the source root run:
+```bash
+./gradlew :firebase-firestore:assembleRelease
+```
+
+## Unit Testing
+
+To run unit tests for Cloud Firestore, from the source root run:
+```bash
+./gradlew :firebase-firestore:check
+```
+
+## Integration Testing
+
+Running integration tests requires a Firebase project because they would try
+to connect to the Firestore backends.
+
+See [here](../README.md#project-setup) for how to setup a project.
+
+Once you setup the project, download `google-services.json` and place it in
+the source root.
+
+Make sure you have created a Firestore instance for your project, before
+you proceed.
+
+### Run on Local Emulator
+
+Then simply run:
+```bash
+./gradlew :firebase-firestore:connectedCheck
+```
+
+### Run on Firebase Test Lab
+
+You can also test on Firebase Test Lab, which allow you to run the integration
+tests on devices hosted in Google data center.
+
+See [here](../README.md#running-integration-tests-on-firebase-test-lab) for
+instructions of how to setup Firebase Test Lab for your project.
+
+Run:
+```bash
+./gradlew :firebase-firestore:deviceCheck
+```
+
+## Code Formatting
+
+Run below to format Java code:
+```bash
+./gradlew :firebase-firestore:googleJavaFormat
+```
+
+See [here](../README.md#code-formatting) if you want to be able to format code
+from within Android Studio.
+
+## Build Local Jar of Firestore SDK
+
+Run:
+```bash
+./gradlew publishAllToLocal
+```
+
+This will publish firebase SDK at SNAPSHOT versions. All pom level dependencies
+within the published artifacts will also point to SNAPSHOT versions that are
+co-published. The results will be built into your local maven repo.
+
+Developers may then take a dependency on these locally published versions by adding
+the `mavenLocal()` repository to your [repositories
+block](https://docs.gradle.org/current/userguide/declaring_repositories.html) in
+your app module's build.gradle.
 
+## Misc
 After importing the project into Android Studio and building successfully
 for the first time, Android Studio will delete the run configuration xml files
 in `./idea/runConfigurations`. Undo these changes with the command: