ci: initial attempt at verify local changes skill

firebase-firestore/.agents/skills/verify-local-changes/SKILL.md

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+---
+name: Verify Local Changes
+description: Verifies local Firebase Android SDK changes.
+---
+
+# Verify Local Changes (Android)
+
+This skill documents how to verify local code changes for the Firebase Android SDK before opening a Pull Request to ensure all GitHub CI checks pass.
+
+All commands should be executed from the root of the `firebase-android-sdk` directory.
+
+---
+
+## Prerequisites
+
+- **Java Development Kit (JDK):** Ensure you are using **JDK 17**.
+- **Android SDK / Platform Tools:** Required for integration tests running on devices/emulators.
+
+---
+
+## Step 0: Format Code & License Headers
+
+Run the Spotless auto-formatter to ensure code style and licensing guidelines pass the CI checks.
+
+1. **Auto-format Code:**
+   ```bash
+   ./gradlew :firebase-firestore:spotlessApply
+   ```
+
+2. **Verify Format Compliance:**
+   ```bash
+   ./gradlew :firebase-firestore:spotlessCheck
+   ```
+
+3. **Verify Copyright Headers:**
+   Ensure all files have valid copyright headers using `fireci`:
+   ```bash
+   # Install fireci locally if not already installed
+   pip3 install -e "ci/fireci"
+
+   # Run copyright check
+   fireci copyright_check -e py -e gradle -e java -e kt -e groovy -e sh -e proto
+   ```
+
+---
+
+## Step 1: Unit Testing & Static Analysis (ErrorProne)
+
+Run unit tests and compile-time checks using ErrorProne to catch potential bugs (e.g., resource leaks, bad API patterns, invalid annotations).
+
+```bash
+./gradlew :firebase-firestore:check withErrorProne
+```
+
+> [!TIP]
+> `withErrorProne` is a marker task that applies the `net.ltgt.errorprone` plugin. Always include it to match CI behavior.
+
+---
+
+## Step 2: Public API Compatibility (SemVer Check)
+
+If you made any changes to the public API surface (classes, methods, parameters, fields), you must ensure they do not break semantic versioning.
+
+```bash
+./gradlew metalavaSemver
+```
+
+---
+
+## Step 3: Integration / System Testing (Emulator)
+
+The standard and fastest way to run system tests locally.
+
+1. **Start the Firestore Emulator:**
+   ```bash
+   gcloud emulators firestore start --host-port=127.0.0.1:8080
+   ```
+
+2. **Run the System Tests targeting the emulator:**
+   ```bash
+   ./gradlew :firebase-firestore:connectedCheck withErrorProne -PtargetBackend="emulator" -PbackendEdition="enterprise"
+   ```
+   > [!NOTE]
+   > Running integration tests requires an active/connected Android Emulator or physical Android device.
+
+---
+
+## Step 4: Integration / System Testing (Production/Nightly)
+
+To run tests against standard production/nightly backends (requires GCP service account and project configurations):
+
+* **Standard Production DB:**
+  ```bash
+  ./gradlew :firebase-firestore:connectedCheck withErrorProne -PtargetBackend="prod" -PbackendEdition="standard" -PtargetDatabaseId="(default)"
+  ```
+
+* **Enterprise Named DB:**
+  ```bash
+  ./gradlew :firebase-firestore:connectedCheck withErrorProne -PtargetBackend="prod" -PbackendEdition="enterprise" -PtargetDatabaseId="enterprise"
+  ```
+
+* **Nightly Backend:**
+  ```bash
+  ./gradlew :firebase-firestore:connectedCheck withErrorProne -PtargetBackend="nightly" -PbackendEdition="enterprise" -PtargetDatabaseId="enterprise"
+  ```
+
+---
+
+## Pro Tips
+
+> [!TIP]
+> **Targeting Specific Test Classes:**
+> To avoid waiting for the entire integration test suite to run, you can specify a single test class or test method using the instrumentation argument:
+> ```bash
+> ./gradlew :firebase-firestore:connectedCheck \
+>   -Pandroid.testInstrumentationRunnerArguments.class=com.google.firebase.firestore.NumericTransformsTest
+> ```
+> This is the preferred approach to testing changes that have a narrow scope and when testing agains production or nightly, because integration tests are slow.