Skip to content

TestConsole

Provides a test implementation of the Effect Console service.

When the test layer is provided, calls made through the Effect console APIs are captured in memory instead of being written to the host console. Tests can then assert on logged values deterministically. This module includes the console layer, helpers for reading captured Console.log and Console.error arguments, and access to the provided test console service.

7 exports Added in v4.0.0 Source

Constructors

make

Added in v4.0.0 Source

Creates a new TestConsole instance that captures all console output. The returned TestConsole implements the Console interface and provides additional methods to retrieve logged messages.

When to use

Use to construct a test console service value directly.

See

  • layer for providing a TestConsole as a Layer

Signature

declare const make: Effect<TestConsole, never, never>;

Layers

layer

Added in v4.0.0 Source

Creates a Layer which constructs a TestConsole. This layer can be used to provide a TestConsole implementation for testing purposes.

When to use

Use to run an effect with console calls captured by TestConsole.

See

  • make for constructing the service value directly
  • testConsoleWith for accessing the provided test console service

Signature

declare const layer: Layer.Layer<TestConsole>;

Models

TestConsole interface

Added in v4.0.0 Source

A TestConsole provides a testable implementation of the Console interface. It captures all console output for testing purposes while maintaining full compatibility with the standard Console API.

When to use

Use to provide a console implementation that records calls for assertions in tests.

Details

This interface extends the standard Console interface and adds methods to retrieve logged messages for verification in tests.

See

  • layer for providing TestConsole to an effect
  • logLines for reading captured Console.log calls
  • errorLines for reading captured Console.error calls

Signature

interface TestConsole extends Console {
  readonly errorLines: Effect<readonly Array<unknown>>;
  readonly logLines: Effect<readonly Array<unknown>>;
}

Other

TestConsole

Added in v4.0.0 Source

The TestConsole namespace provides types and utilities for working with test console implementations.

When to use

Use when referring to types nested under the TestConsole namespace.

Testing

errorLines

Added in v4.0.0 Source

Returns an array of all items that have been logged by the program using Console.error thus far.

When to use

Use to assert on captured Console.error output from a program provided with TestConsole.layer.

See

  • logLines for reading captured Console.log output
  • layer for capturing console calls during a test

Signature

declare const errorLines: Effect.Effect<ReadonlyArray<unknown>, never, never>;

logLines

Added in v4.0.0 Source

Returns an array of all items that have been logged by the program using Console.log thus far.

When to use

Use to assert on captured Console.log output from a program provided with TestConsole.layer.

See

  • errorLines for reading captured Console.error output
  • layer for capturing console calls during a test

Signature

declare const logLines: Effect.Effect<ReadonlyArray<unknown>, never, never>;

testConsoleWith

Added in v4.0.0 Source

Retrieves the TestConsole service for this test and uses it to run the specified workflow.

When to use

Use to access the provided test console service inside an effect.

See

  • layer for providing the test console service
  • logLines for reading captured Console.log calls directly
  • errorLines for reading captured Console.error calls directly

Signature

declare function testConsoleWith<A, E, R>(
  f: (console: TestConsole) => Effect<A, E, R>,
): Effect<A, E, R>;