TestByExample

Write Tests as Examples on the Method-under-test

Progress

THIS PROJECT IS STILL WIP

• Example Call Code Generation
• Run the generated code with JUnit
• Run Action with Intellij Plugin
• Syntax Highlighting in Intellij Plugin

Goal

This project will enable you to annotate a function or method with @Example and execute it as you would run a Unit-Test. All values in the annotation are strings, but will be executed with generated code in the same scope as the file.

class Bar {
  @Example(
    self = "Bar()",
    params = ["42"],
    result = "44")
  fun foo(p: Int): Int {
    return p + 2
  }
}

Interface

• self: Object the method is run on (Can be empty for functions)
• params: Array of parameters for the function
• context: Function that will be called before the test to setup state
• result: Value that will be compared to the actual return value to make test suceed/fail

Technologies

1. For generating the code that calls the examples KSP is used.
2. The JUnit Platform Launcher API is used to run the generated code.
3. The Intellij Plugin provides syntax highlighting for the example code and an action to run the example.

Useful Links

• https://blogs.oracle.com/javamagazine/post/junit-build-custom-test-engines-java