Include spec for exception mapping behaviors

Author: Joe McCall

grails-test-suite-uber/src/test/groovy/grails/test/mixin/UrlMappingsTestMixinTests.groovy

@@ -166,6 +166,17 @@ class UrlMappingsTestMixinTests {
         assertUrlMapping('/users/timmy', controller: 'user', action: 'update', method: 'put') { name = 'timmy' }
     }
 
+    @Test
+    @Issue('https://github.com/grails/grails-core/issues/10226')
+    void testExceptionUrlMapping() {
+        mockController(ExceptionTestErrorsController)
+        mockUrlMappings(ExceptionTestUrlMappings)
+
+        assertForwardUrlMapping(500, controller: 'exceptionTestErrors', action: 'handleNullPointer', exception: new NullPointerException())
+        assertForwardUrlMapping(500, controller: 'exceptionTestErrors', action: 'handleIllegalArgument', exception: new IllegalArgumentException())
+        assertForwardUrlMapping(500, controller: 'exceptionTestErrors', action: 'handleDefault')
+    }
+
     @Test
     @Issue('https://github.com/grails/grails-core/issues/9065')
     void testResourcesUrlMapping() {
@@ -282,3 +293,18 @@ class ResourceTestUrlMappings {
         '/person'(resources: 'person')
     }
 }
+
+@Artefact("Controller")
+class ExceptionTestErrorsController {
+    def handleNullPointer() {}
+    def handleIllegalArgument() {}
+    def handleDefault() {}
+}
+
+class ExceptionTestUrlMappings {
+    static mappings = {
+        '500'(controller: 'exceptionTestErrors', action: 'handleNullPointer', exception: NullPointerException)
+        '500'(controller: 'exceptionTestErrors', action: 'handleIllegalArgument', exception: IllegalArgumentException)
+        '500'(controller: 'exceptionTestErrors', action: 'handleDefault')
+    }
+}