junit: Split FuzzTestArgumentsProvider into three providers

This improves readability and prepares us for an upcoming JUnit change
that allows us to retrieve the `ArgumentsProvider` instance that
resulted in a particular invocation, thus removing the need to hackily
mark the arguments.

5 files changed, 107 insertions, 28 deletions

diff --git a/src/main/java/com/code_intelligence/jazzer/junit/AgentConfiguringArgumentsProvider.java b/src/main/java/com/code_intelligence/jazzer/junit/AgentConfiguringArgumentsProvider.java
new file mode 100644
index 00000000..e65f028b
--- /dev/null
+++ b/src/main/java/com/code_intelligence/jazzer/junit/AgentConfiguringArgumentsProvider.java
@@ -0,0 +1,43 @@
+/*
+ * Copyright 2023 Code Intelligence GmbH
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package com.code_intelligence.jazzer.junit;
+
+import java.util.stream.Stream;
+import org.junit.jupiter.api.extension.ExtensionContext;
+import org.junit.jupiter.params.provider.Arguments;
+import org.junit.jupiter.params.provider.ArgumentsProvider;
+import org.junit.jupiter.params.support.AnnotationConsumer;
+
+public class AgentConfiguringArgumentsProvider
+    implements ArgumentsProvider, AnnotationConsumer<FuzzTest> {
+  private FuzzTest fuzzTest;
+
+  @Override
+  public void accept(FuzzTest fuzzTest) {
+    this.fuzzTest = fuzzTest;
+  }
+
+  @Override
+  public Stream<? extends Arguments> provideArguments(ExtensionContext extensionContext)
+      throws Exception {
+    // FIXME(fmeum): Calling this here feels like a hack. There should be a lifecycle hook that runs
+    //  before the argument discovery for a ParameterizedTest is kicked off, but I haven't found
+    //  one.
+    FuzzTestExecutor.configureAndInstallAgent(extensionContext, fuzzTest.maxDuration());
+    return Stream.empty();
+  }
+}
diff --git a/src/main/java/com/code_intelligence/jazzer/junit/BUILD.bazel b/src/main/java/com/code_intelligence/jazzer/junit/BUILD.bazel
index 6ed5caca..82f055f6 100644
--- a/src/main/java/com/code_intelligence/jazzer/junit/BUILD.bazel
+++ b/src/main/java/com/code_intelligence/jazzer/junit/BUILD.bazel
@@ -22,9 +22,11 @@ java_library(
 java_library(
     name = "fuzz_test",
     srcs = [
+        "AgentConfiguringArgumentsProvider.java",
         "FuzzTest.java",
-        "FuzzTestArgumentsProvider.java",
         "FuzzTestExtensions.java",
+        "FuzzingArgumentsProvider.java",
+        "SeedArgumentsProvider.java",
     ],
     visibility = [
         "//examples/junit/src/test/java/com/example:__pkg__",
diff --git a/src/main/java/com/code_intelligence/jazzer/junit/FuzzTest.java b/src/main/java/com/code_intelligence/jazzer/junit/FuzzTest.java
index 773e4a0d..041db96d 100644
--- a/src/main/java/com/code_intelligence/jazzer/junit/FuzzTest.java
+++ b/src/main/java/com/code_intelligence/jazzer/junit/FuzzTest.java
@@ -86,7 +86,9 @@ import org.junit.jupiter.params.provider.ArgumentsSource;
  */
 @Target({ElementType.METHOD})
 @Retention(RetentionPolicy.RUNTIME)
-@ArgumentsSource(FuzzTestArgumentsProvider.class)
+@AgentConfiguringArgumentsProviderArgumentsSource
+@ArgumentsSource(SeedArgumentsProvider.class)
+@FuzzingArgumentsProviderArgumentsSource
 @ExtendWith(FuzzTestExtensions.class)
 // {0} is expanded to the basename of the seed by the ArgumentProvider.
 @ParameterizedTest(name = "{0}")
@@ -105,3 +107,16 @@ public @interface FuzzTest {
    */
   String maxDuration() default "5m";
 }
+
+// Internal use only.
+// These wrappers are needed only because the container annotation for @ArgumentsSource,
+// @ArgumentsSources, can't be applied to annotations.
+@Target({ElementType.ANNOTATION_TYPE})
+@Retention(RetentionPolicy.RUNTIME)
+@ArgumentsSource(AgentConfiguringArgumentsProvider.class)
+@interface AgentConfiguringArgumentsProviderArgumentsSource {}
+
+@Target({ElementType.ANNOTATION_TYPE})
+@Retention(RetentionPolicy.RUNTIME)
+@ArgumentsSource(FuzzingArgumentsProvider.class)
+@interface FuzzingArgumentsProviderArgumentsSource {}
diff --git a/src/main/java/com/code_intelligence/jazzer/junit/FuzzingArgumentsProvider.java b/src/main/java/com/code_intelligence/jazzer/junit/FuzzingArgumentsProvider.java
new file mode 100644
index 00000000..61a8d3fe
--- /dev/null
+++ b/src/main/java/com/code_intelligence/jazzer/junit/FuzzingArgumentsProvider.java
@@ -0,0 +1,42 @@
+/*
+ * Copyright 2023 Code Intelligence GmbH
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package com.code_intelligence.jazzer.junit;
+
+import static com.code_intelligence.jazzer.junit.Utils.isFuzzing;
+
+import java.util.stream.Stream;
+import org.junit.jupiter.api.extension.ExtensionContext;
+import org.junit.jupiter.params.provider.Arguments;
+import org.junit.jupiter.params.provider.ArgumentsProvider;
+
+class FuzzingArgumentsProvider implements ArgumentsProvider {
+  @Override
+  public Stream<? extends Arguments> provideArguments(ExtensionContext extensionContext) {
+    if (!isFuzzing(extensionContext)) {
+      return Stream.empty();
+    }
+
+    // When fuzzing, supply a special set of arguments that our InvocationInterceptor uses as a
+    // sign to start fuzzing.
+    // FIXME: This is a hack that is needed only because there does not seem to be a way to
+    //  communicate out of band that a certain invocation was triggered by a particular argument
+    //  provider. We should get rid of this hack as soon as
+    //  https://github.com/junit-team/junit5/issues/3282 has been addressed.
+    return Stream.of(
+        Utils.getMarkedArguments(extensionContext.getRequiredTestMethod(), "Fuzzing..."));
+  }
+}
diff --git a/src/main/java/com/code_intelligence/jazzer/junit/FuzzTestArgumentsProvider.java b/src/main/java/com/code_intelligence/jazzer/junit/SeedArgumentsProvider.java
index b8d06d71..50618252 100644
--- a/src/main/java/com/code_intelligence/jazzer/junit/FuzzTestArgumentsProvider.java
+++ b/src/main/java/com/code_intelligence/jazzer/junit/SeedArgumentsProvider.java
@@ -14,6 +14,7 @@
 
 package com.code_intelligence.jazzer.junit;
 
+import static com.code_intelligence.jazzer.junit.Utils.isFuzzing;
 import static org.junit.jupiter.api.Named.named;
 import static org.junit.jupiter.params.provider.Arguments.arguments;
 
@@ -45,40 +46,16 @@ import java.util.stream.Stream;
 import org.junit.jupiter.api.extension.ExtensionContext;
 import org.junit.jupiter.params.provider.Arguments;
 import org.junit.jupiter.params.provider.ArgumentsProvider;
-import org.junit.jupiter.params.support.AnnotationConsumer;
 
-class FuzzTestArgumentsProvider implements ArgumentsProvider, AnnotationConsumer<FuzzTest> {
+class SeedArgumentsProvider implements ArgumentsProvider {
   private static final String INCORRECT_PARAMETERS_MESSAGE =
       "Methods annotated with @FuzzTest must take at least one parameter";
 
   private boolean invalidCorpusFilesPresent = false;
-  private FuzzTest fuzzTest;
-
-  @Override
-  public void accept(FuzzTest annotation) {
-    this.fuzzTest = annotation;
-  }
-
   @Override
   public Stream<? extends Arguments> provideArguments(ExtensionContext extensionContext)
       throws IOException {
-    // FIXME(fmeum): Calling this here feels like a hack. There should be a lifecycle hook that runs
-    //  before the argument discovery for a ParameterizedTest is kicked off, but I haven't found
-    //  one.
-    FuzzTestExecutor.configureAndInstallAgent(extensionContext, fuzzTest.maxDuration());
-
-    if (Utils.isFuzzing(extensionContext)) {
-      // When fuzzing, supply a special set of arguments that our InvocationInterceptor uses as a
-      // sign to start fuzzing.
-      // FIXME: This is a hack that is needed only because there does not seem to be a way to
-      //  communicate out of band that a certain invocation was triggered by a particular argument
-      //  provider. We should get rid of this hack as soon as
-      //  https://github.com/junit-team/junit5/issues/3282 has been addressed.
-      return Stream.of(
-          Utils.getMarkedArguments(extensionContext.getRequiredTestMethod(), "Fuzzing..."));
-    } else {
-      return provideSeedArguments(extensionContext);
-    }
+    return isFuzzing(extensionContext) ? Stream.empty() : provideSeedArguments(extensionContext);
   }
 
   private Stream<? extends Arguments> provideSeedArguments(ExtensionContext extensionContext)