Allow tests to be written with Java 17 or 21 for access to text blocks

[timtebeek]

What problem are you trying to solve?

Right now our tests use resource files for in and outputs, but these mean there's a disconnect between a test method and what it actually verifies.

Describe the solution you'd like

With text blocks and JavaFileObjects.forSourceString we can instead adopt a test style similar to what we use elsewhere in OpenRewrite. That should help familiarity, and seeing at a glance what a test verifies.

static Compilation compileSource(String fqn, @Language("java") String source, TypeAwareProcessor processor) {
    return compileResource(JavaFileObjects.forSourceString(fqn, source), processor);
}

Additional context

The compileSource method above as already been added in

• Skip method references and lambdas in body #72

[timtebeek]

My quick attempts so far have failed to produce a working setup with Gradle; something to do with toolchains that I think I'm close to, but some help would be appreciated to get this in.

[timtebeek]

Through #57 there's now already two methods that can take a String input.

rewrite-templating/src/test/java/org/openrewrite/java/template/RefasterTemplateProcessorTest.java

Lines 116 to 123 in ab2dee2

	@SuppressWarnings("unused") // use when text blocks are available
	static Compilation compileSource(String fqn, @Language("java") String source) {
	return compile(JavaFileObjects.forSourceString(fqn, source), new RefasterTemplateProcessor());
	}
	static Compilation compileSource(String fqn, @Language("java") String source, TypeAwareProcessor processor) {
	return compile(JavaFileObjects.forSourceString(fqn, source), processor);
	}