More informative error message in case of no implementing class

2 files changed, 7 insertions, 0 deletions

diff --git a/agent/src/main/java/com/code_intelligence/jazzer/autofuzz/AutofuzzConstructionException.java b/agent/src/main/java/com/code_intelligence/jazzer/autofuzz/AutofuzzConstructionException.java
index 760fef3d..e1d775c4 100644
--- a/agent/src/main/java/com/code_intelligence/jazzer/autofuzz/AutofuzzConstructionException.java
+++ b/agent/src/main/java/com/code_intelligence/jazzer/autofuzz/AutofuzzConstructionException.java
@@ -19,6 +19,9 @@ package com.code_intelligence.jazzer.autofuzz;
  * not the actual invocation of an autofuzzed method.
  */
 public class AutofuzzConstructionException extends RuntimeException {
+  public AutofuzzConstructionException(String message) {
+    super(message);
+  }
   public AutofuzzConstructionException(Throwable cause) {
     super(cause);
   }
diff --git a/agent/src/main/java/com/code_intelligence/jazzer/autofuzz/Meta.java b/agent/src/main/java/com/code_intelligence/jazzer/autofuzz/Meta.java
index e31d7201..88826b9b 100644
--- a/agent/src/main/java/com/code_intelligence/jazzer/autofuzz/Meta.java
+++ b/agent/src/main/java/com/code_intelligence/jazzer/autofuzz/Meta.java
@@ -146,6 +146,10 @@ public class Meta {
           cache.put(type, implementingClasses);
         }
       }
+      if (implementingClasses.isEmpty()) {
+        throw new AutofuzzConstructionException(String.format(
+            "Could not find classes implementing %s on the classpath", type.getName()));
+      }
       return consume(data, data.pickValue(implementingClasses));
     } else if (type.getConstructors().length > 0) {
       Constructor<?> constructor = data.pickValue(type.getConstructors());