mutation: Add a few utility methods

This adds:
* asSubclassOrEmpty as a variant of Class#asSubclass;
* an overload of combine that assembles a SerializingInPlaceMutator;
* an overload of MutatorFactory#createInPlaceOrThrow for AnnotatedType.

1 files changed, 13 insertions, 0 deletions

diff --git a/src/test/java/com/code_intelligence/jazzer/mutation/support/TypeSupportTest.java b/src/test/java/com/code_intelligence/jazzer/mutation/support/TypeSupportTest.java
index 6248d799..dcf090b2 100644
--- a/src/test/java/com/code_intelligence/jazzer/mutation/support/TypeSupportTest.java
+++ b/src/test/java/com/code_intelligence/jazzer/mutation/support/TypeSupportTest.java
@@ -17,8 +17,10 @@
 package com.code_intelligence.jazzer.mutation.support;
 
 import static com.code_intelligence.jazzer.mutation.support.TypeSupport.asAnnotatedType;
+import static com.code_intelligence.jazzer.mutation.support.TypeSupport.asSubclassOrEmpty;
 import static com.code_intelligence.jazzer.mutation.support.TypeSupport.withTypeArguments;
 import static com.google.common.truth.Truth.assertThat;
+import static com.google.common.truth.Truth8.assertThat;
 import static org.junit.jupiter.api.Assertions.assertThrows;
 
 import com.code_intelligence.jazzer.mutation.annotation.NotNull;
@@ -191,4 +193,15 @@ class TypeSupportTest {
     assertThrows(IllegalArgumentException.class, () -> withTypeArguments(new TypeHolder<List<?>>() {
     }.annotatedType(), asAnnotatedType(String.class)));
   }
+
+  @Test
+  void testAsSubclassOrEmpty() {
+    assertThat(asSubclassOrEmpty(asAnnotatedType(String.class), String.class))
+        .hasValue(String.class);
+    assertThat(asSubclassOrEmpty(asAnnotatedType(String.class), CharSequence.class))
+        .hasValue(String.class);
+    assertThat(asSubclassOrEmpty(asAnnotatedType(CharSequence.class), String.class)).isEmpty();
+    assertThat(asSubclassOrEmpty(new TypeHolder<List<String>>() {
+    }.annotatedType(), List.class)).isEmpty();
+  }
 }