bun-types

--- title: "Test configuration" description: "Learn how to configure Bun test behavior using bunfig.toml and command-line options" --- Configure `bun test` via `bunfig.toml` file and command-line options. This page documents the available configuration options for `bun test`. ## Configuration File You can configure `bun test` behavior by adding a `[test]` section to your `bunfig.toml` file: ```toml title="bunfig.toml" icon="settings" [test] # Options go here ``` ## Test Discovery ### root The `root` option specifies a root directory for test discovery, overriding the default behavior of scanning from the project root. ```toml title="bunfig.toml" icon="settings" [test] root = "src" # Only scan for tests in the src directory ``` This is useful when you want to: - Limit test discovery to specific directories - Exclude certain parts of your project from test scanning - Organize tests in a specific subdirectory structure #### Examples ```toml title="bunfig.toml" icon="settings" [test] # Only run tests in the src directory root = "src" # Run tests in a specific test directory root = "tests" # Run tests in multiple specific directories (not currently supported - use patterns instead) # root = ["src", "lib"] # This syntax is not supported ``` ### Preload Scripts Load scripts before running tests using the `preload` option: ```toml title="bunfig.toml" icon="settings" [test] preload = ["./test-setup.ts", "./global-mocks.ts"] ``` This is equivalent to using `--preload` on the command line: ```bash terminal icon="terminal" bun test --preload ./test-setup.ts --preload ./global-mocks.ts ``` #### Common Preload Use Cases ```ts title="test-setup.ts" icon="/icons/typescript.svg" // Global test setup import { beforeAll, afterAll } from "bun:test"; beforeAll(() => { // Set up test database setupTestDatabase(); }); afterAll(() => { // Clean up cleanupTestDatabase(); }); ``` ```ts title="global-mocks.ts" icon="/icons/typescript.svg" // Global mocks import { mock } from "bun:test"; // Mock environment variables process.env.NODE_ENV = "test"; process.env.API_URL = "http://localhost:3001"; // Mock external dependencies mock.module("./external-api", () => ({ fetchData: mock(() => Promise.resolve({ data: "test" })), })); ``` ## Timeouts ### Default Timeout Set the default timeout for all tests: ```toml title="bunfig.toml" icon="settings" [test] timeout = 10000 # 10 seconds (default is 5000ms) ``` This applies to all tests unless overridden by individual test timeouts: ```ts title="test.ts" icon="/icons/typescript.svg" // This test will use the default timeout from bunfig.toml test("uses default timeout", () => { // test implementation }); // This test overrides the default timeout test("custom timeout", () => { // test implementation }, 30000); // 30 seconds ``` ## Reporters ### JUnit Reporter Configure the JUnit reporter output file path directly in the config file: ```toml title="bunfig.toml" icon="settings" [test.reporter] junit = "path/to/junit.xml" # Output path for JUnit XML report ``` This complements the `--reporter=junit` and `--reporter-outfile` CLI flags: ```bash terminal icon="terminal" # Equivalent command line usage bun test --reporter=junit --reporter-outfile=./junit.xml ``` #### Multiple Reporters You can use multiple reporters simultaneously: ```bash terminal icon="terminal" # CLI approach bun test --reporter=junit --reporter-outfile=./junit.xml # Config file approach ``` ```toml title="bunfig.toml" icon="settings" [test.reporter] junit = "./reports/junit.xml" [test] # Also enable coverage reporting coverage = true coverageReporter = ["text", "lcov"] ``` ## Memory Usage ### smol Mode Enable the `--smol` memory-saving mode specifically for the test runner: ```toml title="bunfig.toml" icon="settings" [test] smol = true # Reduce memory usage during test runs ``` This is equivalent to using the `--smol` flag on the command line: ```bash terminal icon="terminal" bun test --smol ``` The `smol` mode reduces memory usage by: - Using less memory for the JavaScript heap - Being more aggressive about garbage collection - Reducing buffer sizes where possible This is useful for: - CI environments with limited memory - Large test suites that consume significant memory - Development environments with memory constraints ## Test execution ### concurrentTestGlob Automatically run test files matching a glob pattern with concurrent test execution enabled. This is useful for gradually migrating test suites to concurrent execution or for running specific test types concurrently. ```toml title="bunfig.toml" icon="settings" [test] concurrentTestGlob = "**/concurrent-*.test.ts" # Run files matching this pattern concurrently ``` Test files matching this pattern will behave as if the `--concurrent` flag was passed, running all tests within those files concurrently. This allows you to: - Gradually migrate your test suite to concurrent execution - Run integration tests concurrently while keeping unit tests sequential - Separate fast concurrent tests from tests that require sequential execution The `--concurrent` CLI flag will override this setting when specified, forcing all tests to run concurrently regardless of the glob pattern. #### randomize Run tests in random order to identify tests with hidden dependencies: ```toml title="bunfig.toml" icon="settings" [test] randomize = true ``` #### seed Specify a seed for reproducible random test order. Requires `randomize = true`: ```toml title="bunfig.toml" icon="settings" [test] randomize = true seed = 2444615283 ``` #### rerunEach Re-run each test file multiple times to identify flaky tests: ```toml title="bunfig.toml" icon="settings" [test] rerunEach = 3 ``` ## Coverage Options ### Basic Coverage Settings ```toml title="bunfig.toml" icon="settings" [test] # Enable coverage by default coverage = true # Set coverage reporter coverageReporter = ["text", "lcov"] # Set coverage output directory coverageDir = "./coverage" ``` ### Skip Test Files from Coverage Exclude files matching test patterns (e.g., `*.test.ts`) from the coverage report: ```toml title="bunfig.toml" icon="settings" [test] coverageSkipTestFiles = true # Exclude test files from coverage reports ``` ### Coverage Thresholds The coverage threshold can be specified either as a number or as an object with specific thresholds: ```toml title="bunfig.toml" icon="settings" [test] # Simple threshold - applies to lines, functions, and statements coverageThreshold = 0.8 # Detailed thresholds coverageThreshold = { lines = 0.9, functions = 0.8, statements = 0.85 } ``` Setting any of these enables `fail_on_low_coverage`, causing the test run to fail if coverage is below the threshold. #### Threshold Examples ```toml title="bunfig.toml" icon="settings" [test] # Require 90% coverage across the board coverageThreshold = 0.9 # Different requirements for different metrics coverageThreshold = { lines = 0.85, # 85% line coverage functions = 0.90, # 90% function coverage statements = 0.80 # 80% statement coverage } ``` ### Coverage Path Ignore Patterns Exclude specific files or file patterns from coverage reports using glob patterns: ```toml title="bunfig.toml" icon="settings" [test] # Single pattern coveragePathIgnorePatterns = "**/*.spec.ts" # Multiple patterns coveragePathIgnorePatterns = [ "**/*.spec.ts", "**/*.test.ts", "src/utils/**", "*.config.js", "generated/**", "vendor/**" ] ``` Files matching any of these patterns will be excluded from coverage calculation and reporting. See the [coverage documentation](/docs/test/code-coverage) for more details and examples. #### Common Ignore Patterns ```toml title="bunfig.toml" icon="settings" [test] coveragePathIgnorePatterns = [ # Test files "**/*.test.ts", "**/*.spec.ts", "**/*.e2e.ts", # Configuration files "*.config.js", "*.config.ts", "webpack.config.*", "vite.config.*", # Build output "dist/**", "build/**", ".next/**", # Generated code "generated/**", "**/*.generated.ts", # Vendor/third-party "vendor/**", "third-party/**", # Utilities that don't need testing "src/utils/constants.ts", "src/types/**" ] ``` ### Sourcemap Handling Internally, Bun transpiles every file. That means code coverage must also go through sourcemaps before they can be reported. We expose this as a flag to allow you to opt out of this behavior, but it will be confusing because during the transpilation process, Bun may move code around and change variable names. This option is mostly useful for debugging coverage issues. ```toml title="bunfig.toml" icon="settings" [test] coverageIgnoreSourcemaps = true # Don't use sourcemaps for coverage analysis ``` <Warning> When using this option, you probably want to stick a `// @bun` comment at the top of the source file to opt out of the transpilation process. </Warning> ## Install Settings Inheritance The `bun test` command inherits relevant network and installation configuration (registry, cafile, prefer, exact, etc.) from the `[install]` section of `bunfig.toml`. This is important if tests need to interact with private registries or require specific install behaviors triggered during the test run. ```toml title="bunfig.toml" icon="settings" [install] # These settings are inherited by bun test registry = "https://npm.company.com/" exact = true prefer = "offline" [test] # Test-specific configuration coverage = true timeout = 10000 ``` ## Environment Variables You can also set environment variables in your configuration that affect test behavior: ```toml title="bunfig.toml" icon="settings" [env] NODE_ENV = "test" DATABASE_URL = "postgresql://localhost:5432/test_db" LOG_LEVEL = "error" [test] coverage = true ``` ## Complete Configuration Example Here's a comprehensive example showing all available test configuration options: ```toml title="bunfig.toml" icon="settings" [install] # Install settings inherited by tests registry = "https://registry.npmjs.org/" exact = true [env] # Environment variables for tests NODE_ENV = "test" DATABASE_URL = "postgresql://localhost:5432/test_db" API_URL = "http://localhost:3001" LOG_LEVEL = "error" [test] # Test discovery root = "src" preload = ["./test-setup.ts", "./global-mocks.ts"] # Execution settings timeout = 10000 smol = true # Coverage configuration coverage = true coverageReporter = ["text", "lcov"] coverageDir = "./coverage" coverageThreshold = { lines = 0.85, functions = 0.90, statements = 0.80 } coverageSkipTestFiles = true coveragePathIgnorePatterns = [ "**/*.spec.ts", "src/utils/**", "*.config.js", "generated/**" ] # Advanced coverage settings coverageIgnoreSourcemaps = false # Reporter configuration [test.reporter] junit = "./reports/junit.xml" ``` ## CLI Override Behavior Command-line options always override configuration file settings: ```toml title="bunfig.toml" icon="settings" [test] timeout = 5000 coverage = false ``` ```bash terminal icon="terminal" # These CLI flags override the config file bun test --timeout 10000 --coverage # timeout will be 10000ms and coverage will be enabled ``` ## Conditional Configuration You can use different configurations for different environments: ```toml title="bunfig.toml" icon="settings" [test] # Default test configuration coverage = false timeout = 5000 # Override for CI environment [test.ci] coverage = true coverageThreshold = 0.8 timeout = 30000 ``` Then in CI: ```bash terminal icon="terminal" # Use CI-specific settings bun test --config=ci ``` ## Validation and Troubleshooting ### Invalid Configuration Bun will warn about invalid configuration options: ```toml title="bunfig.toml" icon="settings" [test] invalidOption = true # This will generate a warning ``` ### Common Configuration Issues 1. **Path Resolution**: Relative paths in config are resolved relative to the config file location 2. **Pattern Matching**: Glob patterns use standard glob syntax 3. **Type Mismatches**: Ensure numeric values are not quoted unless they should be strings ```toml title="bunfig.toml" icon="settings" [test] # Correct timeout = 10000 # Incorrect - will be treated as string timeout = "10000" ``` ### Debugging Configuration To see what configuration is being used: ```bash terminal icon="terminal" # Show effective configuration bun test --dry-run # Verbose output to see configuration loading bun test --verbose ```