• Closes AssertJ: Refactor assertThat(x instanceof Type).isTrue() to assertThat(x).isInstanceOf(Type.class) #1030

• When the expression inside assertThat(...) is an instanceof check, the AssertJ best-practices recipe previously left it as a literal boolean port (assertThat(error instanceof RuntimeException).isTrue()), so the failure message was just "expected true but was false" rather than describing the actual type. This is the J.InstanceOf sibling of AssertJ: Refactor assertThat with < or > in the expression to assertThat(actual).isGreaterThan(expected) or assertThat(actual).isLessThan(expected) #814 (</> comparisons): the argument of assertThat(...) is a non-J.MethodInvocation boolean expression that the existing SimplifyChainedAssertJAssertion skips.

Change

New recipe SimplifyAssertJInstanceOfAssertion, added to the org.openrewrite.java.testing.assertj.Assertj recipe list:

assertThat(error instanceof RuntimeException).isTrue();
assertThat(error instanceof RuntimeException).isFalse();

becomes

assertThat(error).isInstanceOf(RuntimeException.class);
assertThat(error).isNotInstanceOf(RuntimeException.class);

It also handles:

• the parenthesized form assertThat((error instanceof RuntimeException))
• the negated form assertThat(!(x instanceof T)).isTrue() → isNotInstanceOf (and .isFalse() → isInstanceOf)
• qualified Assertions.assertThat(...) as well as the static import
• array types (String[].class)

It deliberately skips Java 16+ pattern bindings (x instanceof String s), whose variable may be referenced later.

The previously commented-out instanceof case in AssertJBestPracticesTest is now enabled to confirm end-to-end coverage through the full Assertj recipe.