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Kotest Test Framework

website·Indexed 34 days ago

https://kotest.io

A flexible and comprehensive testing project for Kotlin, featuring a standalone test framework and assertions library. Documentation covers data-driven testing, temporary file management, matcher modules, and Power Assert support across versions 5.3.x through 6.3.

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What's inside Kotest

  1. Overview of Kotest Testing Styles

    Kotest provides 8 different testing styles (Specs) to structure test definitions. There are no functional differences between them; all support the same configurations (threads, tags, etc.). To use a style, create a class that extends the desired Spec and define test cases within the init { } block (or the constructor lambda).

    Test StyleInspired By
    Behavior SpecGherkin / BDD frameworks
    Describe SpecJavascript frameworks / RSpec
    Expect SpecKotest original
    Feature SpecCucumber
    Fun SpecScalaTest
    Free SpecScalaTest
    Should SpecKotest original
    String SpecKotest original
    Word SpecScalaTest

  3. Overview of Kotest testing styles

    Kotest provides 10 different test layout styles. There are no functional differences between them; they all support the same configurations (threads, tags, etc.). To use a style, create a class that extends the desired test style and define test cases within an init { } block (or the constructor lambda).

  4. Overview of Kotest testing styles

    Kotest provides 10 different test layout styles. There are no functional differences between them; all support the same configurations (threads, tags, etc.). To use a style, create a class that extends the specific test style class and define test cases within an init { } block (or the constructor lambda).

  5. Overview of Kotest Team Extensions

    Kotest provides a set of official extensions to integrate with popular frameworks and libraries. Key official extensions include:

    • Allure: Output for the Allure framework.
    • HTML Reporter: Generates HTML reports based on JUnit XML.
    • Instant: Overrides the 'now' context in java.time for time-based testing.
    • JUnit XML: Output in JUnit XML format for reporting tools.
    • Ktor: Matchers specifically for Ktor endpoints.
    • Koin: Integration with the Koin Kotlin DI framework.
    • Mockserver: Integration of Mockserver HTTP servers with the test lifecycle.
    • Spring: Support for Spring beans and Spring test annotations.
    • System: Utilities for integrating with System.* functions.
    • Testcontainers: Ability to run Docker images as part of the test lifecycle.
    • Wiremock: Integration with the Wiremock mock HTTP server.

  7. Overview of Kotest Property Test Generators

    Kotest provides two primary types of generators for property-based testing:

    1. Arbitrary (Arb): Generates random values to explore a wide range of inputs.
    2. Exhaustive: Generates every possible value in a given set to ensure complete coverage.

    Most generators are multi-platform, though some are specific to the JVM or JS. Additional generators for the Arrow library are available as a separate module.

  8. Introduction to Property-Based Testing with Kotest

    Property testing is an alternative to example-based unit testing. Instead of providing a few specific inputs and expected results, property testing feeds hundreds or thousands of randomly generated values into a test to identify edge cases (e.g., negative infinity, empty lists, non-ASCII characters) that developers might overlook. It is used to verify 'properties' or invariants—conditions that should hold true for all possible inputs (e.g., length(a + b) == length(a) + length(b)). It is suitable for testing mathematical laws, validation logic, and any function that benefits from a wide array of input combinations.

  9. Overview of Kotest Testing Styles

    Kotest provides 10 different test layout styles to suit various preferences and backgrounds (e.g., ScalaTest, JUnit, BDD, Cucumber). All styles are functionally identical and support the same configurations (threads, tags, etc.). To use any style, create a class that extends the specific spec class and define test cases within an init { } block.

  10. Overview of advanced Kotest engine extensions

    Kotest provides several advanced extensions that allow developers to hook into the test engine to modify the lifecycle and behavior of specs and tests. These capabilities include intercepting and skipping tests or specs, modifying coroutine contexts, applying custom instantiation logic, filtering execution, and adjusting test output.

  11. Overview of Kotest testing styles

    Kotest provides 8 different styles for defining tests. To use any style, create a class that extends the specific style class and define test cases within the init { } block (or the constructor lambda). There are no functional differences between styles regarding configuration (threads, tags, etc.); the choice is based on preferred structure and familiarity with other frameworks.

  12. Overview of Kotest Team Extensions

    Kotest provides a set of official extensions to integrate the testing framework with common JVM libraries and tools. Key official extensions include:

    • Spring: Support for Spring beans and test annotations.
    • Ktor: Matchers for Ktor endpoints.
    • Koin: Integration with the Koin Kotlin DI framework.
    • Mockserver: Integration of Mockserver HTTP servers with the test lifecycle.
    • System: Utilities for integrating with System.* functions.
    • Instant: Ability to override the 'now' context in java.time.
    • Testcontainers: Support for running Docker images as part of the test lifecycle.
    • Wiremock: Integration with the Wiremock mock HTTP server.
    • Robolectric: Integration of Robolectric with the test lifecycle.
    • Allure: Output support for the Allure framework.
    • JUnit XML: Output in JUnit XML format for reporting tools.
    • HTML Reporter: Generates HTML reports based on JUnit XML output.