If using a RewriteTest with OpenRewrite, how do I test if something is not supposed to change?

Question

I have the following test...

import org.junit.jupiter.api.Test
import org.openrewrite.test.RecipeSpec
import org.openrewrite.test.RewriteTest
import org.openrewrite.yaml.Assertions

class ChangeFilterExpressionPropertiesTest : RewriteTest {
    private val recipeFile = "/META-INF/rewrite/test.yml"
    override fun defaults(spec: RecipeSpec) {
        spec
                .recipeFromResource(recipeFile,"me.ChangeFilterExpressionProperties")
                .cycles(3)
    }
    @Test
    fun `Changes the package`() = rewriteRun(Assertions.yaml(
            """
            spring:
              kafka:
                producer:
                  store-and-forward:
                    filter-expression: '@monitoredTopics.contains(#this.topic())?T(me.Decision).FULL:T(me.Decision).SKIP'
            """.trimIndent(),
            """
            spring:
              kafka:
                producer:
                  store-and-forward:
                    filter-expression: '@monitoredTopics.contains(#this.topic())?T(they.Decision).FULL:T(they.Decision).SKIP'
            """.trimIndent()
    ) { spec -> spec.path("src/main/resources/application.yml") }
    )
    @Test
    fun `Control test`() = rewriteRun(Assertions.yaml(
            """
            spring:
              kafka:
                producer:
                  store-and-forward:
                    filter-expression: 'test'
            """.trimIndent(),
            """
            spring:
              kafka:
                producer:
                  store-and-forward:
                    filter-expression: 'test'
            """.trimIndent()
    ) { spec -> spec.path("src/main/resources/application.yml") }
    )
}

The first test passes as expected, however, I can't get my control test working. It fails with

 java.lang.AssertionError: Recipe was expected to make a change but made no changes.

    at org.openrewrite.test.LargeSourceSetCheckingExpectedCycles.afterCycle(LargeSourceSetCheckingExpectedCycles.java:118)
    at org.openrewrite.RecipeScheduler.runRecipeCycles(RecipeScheduler.java:97)
    at org.openrewrite.RecipeScheduler.scheduleRun(RecipeScheduler.java:41)

How do I test that no changes were made in the control example?

Answer 1

Remove the second text block to assert that a recipe makes no changes at all.

That's all really; but know that you're also always welcome in our Slack for any such questions; the link is at the top of our docs.