Add DefaultExceptionContextTest.testFormattedExceptionMessageExceptionHandling()

src/test/java/org/apache/commons/lang3/ObjectToStringRuntimeException.java

@@ -0,0 +1,40 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one or more
+ * contributor license agreements.  See the NOTICE file distributed with
+ * this work for additional information regarding copyright ownership.
+ * The ASF licenses this file to You 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 org.apache.commons.lang3;
+
+/**
+ * An object that throws a runtime exception when you call {@link #toString()}.
+ */
+public class ObjectToStringRuntimeException {
+
+    private final String message;
+
+    public ObjectToStringRuntimeException(final String message) {
+        this.message = message;
+    }
+
+    /**
+     * Throws {@link IllegalStateException}.
+     *
+     * @throws IllegalStateException always thrown.
+     */
+    @Override
+    public String toString() {
+        throw new IllegalStateException(new NullPointerException(message));
+    }
+}

src/test/java/org/apache/commons/lang3/exception/DefaultExceptionContextTest.java

@@ -16,6 +16,10 @@
  */
 package org.apache.commons.lang3.exception;
 
+import static org.junit.jupiter.api.Assertions.assertEquals;
+import static org.junit.jupiter.api.Assertions.assertTrue;
+
+import org.apache.commons.lang3.ObjectToStringRuntimeException;
 import org.junit.jupiter.api.BeforeEach;
 import org.junit.jupiter.api.Test;
 
@@ -31,10 +35,23 @@ public class DefaultExceptionContextTest extends AbstractExceptionContextTest<De
         super.setUp();
     }
 
+    @Test
+    public void testFormattedExceptionMessageExceptionHandling() {
+        exceptionContext = new DefaultExceptionContext();
+        final String label1 = "throws 1";
+        final String label2 = "throws 2";
+        exceptionContext.addContextValue(label1, new ObjectToStringRuntimeException(label1));
+        exceptionContext.addContextValue(label2, new ObjectToStringRuntimeException(label2));
+        final String message = exceptionContext.getFormattedExceptionMessage(TEST_MESSAGE);
+        assertTrue(message.startsWith(TEST_MESSAGE));
+        assertTrue(message.contains(label1));
+        assertTrue(message.contains(label2));
+    }
+
     @Test
     public void testFormattedExceptionMessageNull() {
         exceptionContext = new DefaultExceptionContext();
-        exceptionContext.getFormattedExceptionMessage(null);
+        assertEquals("", exceptionContext.getFormattedExceptionMessage(null));
     }
 
 }