flutter_test_gen_ai 0.2.0

An LLM-based test generation tool that generates Dart test cases for uncovered code using Google Gemini to improve code coverage.

🚀 Flutter AI Test Generator (flutter_test_gen_ai)

An intelligent, coverage-driven test generation CLI tool for Dart and Flutter applications. Powered by Google Gemini, it automatically identifies untested code (including business logic, state management, repositories, services, and Flutter UI Widgets), gathers surrounding dependency context, and writes, runs, and self-corrects test cases until your test coverage increases.

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⚡ Quick Start

1. Set the API Key

Get a Google Gemini API Key and set it as an environment variable:

export GEMINI_API_KEY="your-api-key-here"

2. Run the Tool

To scan and generate tests for your entire package:

dart run flutter_test_gen_ai --api-key $GEMINI_API_KEY

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🛠️ How to Use Like a Pro

🎯 1. Target Specific Files (Recommended)

By default, the tool scans your entire lib/ directory. For large codebases, this can consume many tokens and API calls. To focus on a specific cubit, controller, or service:

dart run flutter_test_gen_ai --target-files lib/counter_cubit.dart,lib/src/auth_service.dart

Tip

Always target specific files during development to speed up execution and focus Gemini on the code you are actively working on.

🎨 2. Smart Flutter Widget & State Testing

The tool statically analyzes your project to handle advanced architectures out-of-the-box:

• State Management: Generates Cubit and BLoC tests using the bloc_test package.
• Widget Testing: For highly reliable UI testing, add Semantics labels and unique Key parameters to your widgets. The generator automatically discovers them and generates clean testWidgets() suites.

📈 3. Keep Only Effective Tests (Highly Recommended)

If you only want to save tests that actually improve your code coverage (discarding redundant or duplicate tests):

dart run flutter_test_gen_ai -e
# or
dart run flutter_test_gen_ai --effective-tests-only

📊 4. Generate Visual Coverage Diagrams

To automatically generate a color-coded dependency and coverage flowchart (testgen_report.md) utilizing Mermaid:

dart run flutter_test_gen_ai --generate-report

• Green Nodes: Already fully covered.
• Blue Nodes: Covered by newly generated tests in this run.
• Orange Nodes: Code still lacking coverage.

🧠 5. Tune the AI Generator & Context

• Switch Models: Use a different Gemini model if you hit limits or need more power:

  dart run flutter_test_gen_ai --model gemini-3-flash-preview
  

• Limit Dependency Scan Depth: Restrict how deep the static analyzer searches for type definitions when building the context for the LLM (default is 10):

  dart run flutter_test_gen_ai --max-depth 5
  

• Self-Correction Retries: Set how many times the tool will pass compiler errors/test failures back to Gemini to self-heal (default is 5):

  dart run flutter_test_gen_ai --max-attempts 3
  

🔍 6. Debugging & Verbose Mode

If a test keeps failing validation and gets deleted, use verbose mode to write the full prompts and LLM conversation history to testgen_prompts.log for inspection:

dart run flutter_test_gen_ai -v

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⚙️ CLI Options & Configuration

Option	Abbreviation	Default Value	Description
--package	-	.	Root directory of the package to test.
--target-files	-	[]	Comma-separated list of target files (e.g. lib/foo.dart,lib/src/bar.dart) to restrict generation scope.
--effective-tests-only	-e	false	Discards test files if they fail to increase line coverage.
--generate-report	-	false	Generate a Markdown report with a Mermaid dependency and coverage diagram.
--model	-	gemini-3-flash-preview	The Gemini model identifier to query.
--api-key	-	Env GEMINI_API_KEY	Gemini API token for authorization.
--max-depth	-	10	Max depth for tracing declaration dependency trees.
--max-attempts	-	5	Retries allowed for the self-healing engine on test failure.
--port	-	0	Dart VM service port (used for pure Dart packages).
--function-coverage	-f	false	Enable detailed function coverage collection.
--branch-coverage	-b	false	Enable detailed branch coverage collection.
--verbose	-v	false	Outputs detailed logging and writes prompts to testgen_prompts.log.

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📦 What the Tool Handles Automatically

• Framework Compatibility: The tool automatically checks your pubspec.yaml. If it is a Flutter project, it collects coverage via flutter test --coverage (parsing the generated lcov.info). If it is a pure Dart project, it collects coverage directly from the Dart VM Service.
• Flutter Widget Testing: Automatically detects when it is testing a widget class (subclassing StatelessWidget, StatefulWidget, or State). It parses the widget's build method to identify Semantics labels and Key annotations, feeding these UI elements directly to Gemini's prompt to generate compile-safe widget tests (preventing selector hallucinations).
• Auto-installed Dependencies: If your package is missing test, bloc_test, or mocking packages (when state management or data/service layers are parsed), the tool automatically adds them to your dev_dependencies.
• Quarantined Output: All generated tests are written to test/testgen/ to keep them clean and separated from your hand-written test files.

💡 Testing Dart Code Result

[Testing Dart Code Result]

💡 Testing Flutter Code Result

[Testing Flutter Code Result]