Testing and Evolving DSLs Without Breaking Users
Design DSL APIs for stability and test them with readable assertion blocks.
Why DSL Testing Is Different
A DSL is a public API. Changes to it can break every call site in user code. Testing a DSL means verifying both the output it produces and the structure it enforces — including that invalid constructs remain compile errors.
Testing DSL Output
The simplest test: build an object using the DSL and assert on the rendered result or the internal state of the builder.
@Test
fun `div contains a paragraph`() {
val result = html {
body {
div { p("Hi") }
}
}
assertTrue(result.render().contains("<p>"))
}All lessons in this course
- Lambda with Receiver: The DSL Foundation
- @DslMarker: Preventing Receiver Leakage
- Building a Type-Safe HTML/Config DSL
- Testing and Evolving DSLs Without Breaking Users