How does Atlas know which React Native test runner to use?

Atlas identifies `jest (@testing-library/react-native)` as your project's test runner by analyzing your `package.json` and existing test files, ensuring compatibility with your React Native setup.

Can Atlas write tests for platform-specific React Native files like `.ios.tsx`?

Yes, Atlas is designed to read and understand platform-specific files such as `.ios.tsx` and `.android.tsx`, and can generate appropriate unit tests for these React Native components.

How does Atlas ensure new tests match my existing React Native project style?

Atlas uses the `grep` tool to analyze your existing `test.tsx` files, learning your repository's specific `jest` framework, import style, and naming conventions to maintain consistency.

What if the `yarn test` output is very long when running React Native tests?

Atlas truncates test output exceeding 2000 lines or 50 KB for display, but it always saves the full `jest` log to a file for your complete review.

How does Atlas handle code formatting after writing React Native tests?

Atlas can automatically run `yarn prettier --write` on new test files to ensure they conform to your project's formatting standards and confirms native folders (`ios/`, `android/`) remain untouched.

Is my React Native code secure when using Atlas for testing?

Yes, Atlas can build its code index with local Ollama embeddings, keeping your React Native code entirely off third-party servers, and all tool calls are permission-gated for security.

Can Atlas help with large React Native modules that need many tests?

For extensive React Native modules, Atlas can utilize a `todowrite` list to track progress, allowing for incremental test creation and iteration until full coverage is achieved.

Write Unit Tests for Untested React Native Code with Atlas in 2026

In 2026, React Native developers can use Atlas to efficiently write unit tests for previously untested modules, direct integrating with existing project conventions. Atlas leverages your project's `jest (@testing-library/react-native)` setup, manages dependencies with `yarn`, and ensures code consistency with `prettier`, making the testing process straightforward and compliant with your codebase's established patterns.

How Atlas writes unit tests for React Native components

Atlas streamlines the process of writing unit tests for React Native components in 2026 by first understanding your existing codebase. It identifies untested modules and prepares to generate comprehensive tests using your project's `jest (@testing-library/react-native)` setup, ensuring every public function receives proper coverage.

Atlas begins by thoroughly analyzing the target React Native module. Using the `read` tool, it ingests the module's source code, understanding its structure and dependencies. Following this, Atlas employs the `lsp` tool's `documentSymbol` operation to enumerate all exported symbols within the module. This crucial step ensures that no public function, component, or utility is overlooked when generating test cases. For instance, if you have a `src/components/UserProfile.tsx` file, Atlas will identify all exported React components, hooks, or helper functions. This deep understanding allows Atlas to craft a test plan that aims for complete coverage, ensuring that the new tests are not only functional but also aligned with the module's intended public API. The goal is to add real tests that validate the module's behavior, rather than just superficial checks, making your React Native application more robust.

Matching React Native test conventions with Atlas

To ensure new tests integrate perfectly, Atlas meticulously copies your React Native repository's existing test conventions. By using `grep` to locate files like `MyComponent.test.tsx`, Atlas learns the specific `jest` setup, import styles, and naming patterns already in use, maintaining consistency across your 2026 codebase.

A key aspect of integrating new tests into an existing React Native project is adhering to established conventions. Atlas achieves this by first searching for existing test files within your repository. It uses the `grep` tool to scan for common test file patterns, such as `*.test.tsx` or `__tests__/*.js`. Once identified, Atlas analyzes these files to understand the project's specific testing framework setup, which for React Native is typically `jest (@testing-library/react-native)`. It observes how imports are structured (e.g., absolute vs. relative paths), the naming conventions for test suites and individual tests, and common utility functions or render methods used (like `render` from `@testing-library/react-native`). This ensures that when Atlas generates a new test file, for example, `src/components/NewFeature.test.tsx`, it will mirror the style and structure of `src/components/ExistingFeature.test.tsx`, making the new tests indistinguishable from manually written ones and simplifying code reviews.

Generating and running React Native tests with Atlas

Atlas uses its `write` tool to draft new React Native test files, such as `src/utils/data.test.ts`, and then immediately executes them with the `bash` tool, running `yarn test` via `jest`. This iterative process ensures that tests are not just written but are also validated against the module, even if output exceeds 2000 lines.

After understanding the module and its conventions, Atlas proceeds to generate the actual test file. The `write` tool is employed to create the new spec file, for instance, `src/components/AuthButton.test.tsx`. Before any changes are committed to disk, Atlas presents a unified diff for your approval, allowing you to review the proposed test code. Once approved, Atlas switches to the `bash` tool to execute the newly created tests. It runs the real React Native test command, typically `yarn test` (which invokes `jest (@testing-library/react-native)`), targeting the specific new test file or the entire suite. Atlas monitors the test output, reading failures and successes. If the test output is extensive, exceeding 2000 lines or 50 KB, Atlas truncates it for display but saves the full log to a file for your detailed inspection. This immediate execution is critical; a test that was never run is not a test. Atlas then uses the `edit` tool to iterate on the test file, making adjustments based on the failures until the test suite turns green. For larger modules requiring many tests, Atlas can maintain progress using a `todowrite` list, breaking down the task into manageable chunks.

Reviewing and approving Atlas's React Native code changes

Atlas prioritizes safety and transparency when modifying your React Native codebase. Every tool call is permission-gated, and all file edits, like creating `src/hooks/useAuth.test.ts`, are presented as a unified diff for explicit approval. This includes a final `prettier` run to ensure formatting consistency in 2026.

The integrity of your React Native project is paramount, and Atlas is designed with multiple layers of review and safety. Before any action that modifies your codebase, Atlas operates in a read-only plan agent, drafting its strategy. Only after your explicit approval does it switch to a build agent. Crucially, every single tool call that could alter files, such as the `write` tool creating a new `src/components/Header.test.tsx` file or the `bash` tool running `yarn prettier --write`, is permission-gated. This means Atlas will ask for your consent before executing. For every file edit, Atlas computes and surfaces a unified diff, allowing you to meticulously review the proposed changes before they are written to disk. This granular control ensures you have full oversight of the generated test code. After the tests are written and passing, Atlas can run `yarn prettier --write` to automatically format the new test files, ensuring they conform to your project's styling guidelines. A final check confirms that sensitive native folders like `ios/` and `android/` were not touched by accident, preserving the integrity of your platform-specific configurations.

Atlas's local and secure approach to React Native testing

Atlas offers a secure and private way to enhance your React Native testing workflow. It can build its code index using local Ollama embeddings, ensuring that your proprietary code remains entirely on your machine and off third-party servers, a critical security feature for 2026 development.

Security and privacy are fundamental considerations for any development tool, especially when dealing with proprietary React Native code. Atlas addresses this by offering the capability to build its code index with local Ollama embeddings. This means that your sensitive source code, including `package.json`, `ios/Podfile`, `android/build.gradle`, and all your `.tsx` files, never leaves your local environment to be processed by external servers. This "terminal-native" approach provides peace of mind, knowing your intellectual property is protected. Furthermore, Atlas integrates deeply with `git`, allowing it to read branches, status, and diffs. It can stage and create commits on your behalf, providing a complete version control workflow. Atlas also snapshots file changes as git patches, so any edits made during the test generation and iteration process can be easily diffed, reviewed, and rolled back if necessary, offering robust control over your codebase's evolution.

Step by step

01Read the React Native module: Use `atlas read src/components/MyComponent.tsx` to let Atlas understand the component's structure and logic.
02Enumerate exported symbols: Run `atlas lsp documentSymbol src/components/MyComponent.tsx` to identify all public functions and components that require testing.
03Discover existing test conventions: Execute `atlas grep "test.tsx" src/` to find existing `jest (@testing-library/react-native)` test files and learn the project's specific naming and import styles.
04Draft the new test file: Use `atlas write src/components/MyComponent.test.tsx` to generate the initial test spec, reviewing the unified diff for approval before writing to disk.
05Run the React Native tests: Execute `atlas bash "yarn test src/components/MyComponent.test.tsx"` to run the newly created tests with `jest` and observe the output.
06Iterate on test failures: Use `atlas edit src/components/MyComponent.test.tsx` to refine the test code based on `jest` failures until all tests pass.
07Format the new test file: Run `atlas bash "yarn prettier --write src/components/MyComponent.test.tsx"` to ensure the new test file adheres to your project's `prettier` formatting rules.
08Commit the changes: Use `atlas git commit -m "feat: Add unit tests for MyComponent"` to stage and commit the new, passing test file to your repository.

Frequently asked questions

How does Atlas know which React Native test runner to use?: Atlas identifies `jest (@testing-library/react-native)` as your project's test runner by analyzing your `package.json` and existing test files, ensuring compatibility with your React Native setup.
Can Atlas write tests for platform-specific React Native files like `.ios.tsx`?: Yes, Atlas is designed to read and understand platform-specific files such as `.ios.tsx` and `.android.tsx`, and can generate appropriate unit tests for these React Native components.
How does Atlas ensure new tests match my existing React Native project style?: Atlas uses the `grep` tool to analyze your existing `test.tsx` files, learning your repository's specific `jest` framework, import style, and naming conventions to maintain consistency.
What if the `yarn test` output is very long when running React Native tests?: Atlas truncates test output exceeding 2000 lines or 50 KB for display, but it always saves the full `jest` log to a file for your complete review.
How does Atlas handle code formatting after writing React Native tests?: Atlas can automatically run `yarn prettier --write` on new test files to ensure they conform to your project's formatting standards and confirms native folders (`ios/`, `android/`) remain untouched.
Is my React Native code secure when using Atlas for testing?: Yes, Atlas can build its code index with local Ollama embeddings, keeping your React Native code entirely off third-party servers, and all tool calls are permission-gated for security.
Can Atlas help with large React Native modules that need many tests?: For extensive React Native modules, Atlas can utilize a `todowrite` list to track progress, allowing for incremental test creation and iteration until full coverage is achieved.

Try Atlas in your terminal

The terminal-native AI coding agent. Free core, single binary.

Install Atlas

Related guides

Write Unit Tests for Untested Code with Atlas in 2026

How to write unit tests for untested code with Atlas in 2026: the lsp tool enumerates exported symbols, grep copies repo conventions, and bash actually runs the suite.

Atlas for React Native: Terminal-Native AI Coding Across the Native Boundary in 2026

Atlas is a terminal-native AI coding agent for React Native in 2026. Work across the New Architecture, native modules, and platform-specific files with diff-first review.

Diagnose a hanging or long-running command in React Native with Atlas in 2026

In 2026, React Native developers use Atlas to quickly diagnose hanging `yarn` scripts or `jest` tests. Pinpoint if a command is genuinely slow or blocked on interactive input, and get your build unstuck.

Upgrade a dependency and fix the breakage in React Native with Atlas in 2026

Upgrade React Native dependencies in 2026 with Atlas. Automatically fix compile and test failures using `yarn`, `jest`, and `prettier` for a smooth migration.

Trace a runtime bug from a stack trace in React Native with Atlas in 2026

Pinpoint and fix runtime bugs in React Native from production stack traces without a debugger. Atlas uses your `package.json` and `ios/Podfile` to quickly identify issues.

Self-review Your Working Diff Before Committing in React Native with Atlas in 2026

Catch your own mistakes in React Native diffs before committing with Atlas. Use `jest`, `prettier`, and `yarn` to ensure quality in your 2026 mobile projects.

Research a Third-Party API for React Native Integration with Atlas in 2026

Streamline third-party API research for React Native apps in 2026 with Atlas. Understand API shapes, integrate safely, and verify changes with yarn, jest, and prettier before committing.

Locate Where a Behavior is Implemented in React Native with Atlas in 2026

Pinpoint the exact file and symbol for any React Native behavior using Atlas's semantic search, grep, and LSP tools. Accelerate debugging and feature development in your 2026 React Native projects.

Browse this resource hub