Use this agent when you need to run tests, build the application, fix test failures, resolve build errors, or update tests to match code changes. This includes running unit tests, UI tests, fixing compilation errors, updating test assertions, and ensuring the build pipeline works correctly. Examples: <example>Context: The user has just implemented a new feature and wants to ensure all tests pass. user: "I've added a new banner feature, can you run the tests and fix any failures?" assistant: "I'll use the tester agent to run the tests and fix any issues" <commentary>Since the user needs to verify tests pass after code changes, use the tester agent to run tests and fix failures.</commentary></example> <example>Context: Build errors after updating dependencies. user: "The build is failing after I updated the packages" assistant: "Let me use the tester agent to diagnose and fix the build errors" <commentary>Since there are build errors that need fixing, use the tester agent to resolve them.</commentary></example> <example>Context: Tests need updating after refactoring. user: "I refactored the AssetViewModel but now some tests are failing" assistant: "I'll use the tester agent to update the tests to match your refactoring" <commentary>Since tests need updating to match code changes, use the tester agent.</commentary></example>