add exception to test-case-finished event (#952)

Author: gd46

features/fixtures/event_protocol_formatter/failed.ndjson

@@ -7,5 +7,5 @@
 {"type":"test-case-started","sourceLocation":{"uri":"features/a.feature","line":2}}
 {"type":"test-step-started","index":0,"testCase":{"sourceLocation":{"uri":"features/a.feature","line":2}}}
 {"type":"test-step-finished","index":0,"result":{"duration":0,"exception":"Error: my error\n    at World.<anonymous> (features/step_definitions/steps.js:4:51)","status":"failed"},"testCase":{"sourceLocation":{"uri":"features/a.feature","line":2}}}
-{"type":"test-case-finished","result":{"duration":0,"status":"failed"},"sourceLocation":{"uri":"features/a.feature","line":2}}
+{"type":"test-case-finished","result":{"duration":0,"status":"failed","exception":"Error: my error\n    at World.<anonymous> (features/step_definitions/steps.js:4:51)"},"sourceLocation":{"uri":"features/a.feature","line":2}}
 {"type":"test-run-finished","result":{"duration":0,"success":false}}

src/runtime/test_case_runner.js

@@ -143,6 +143,9 @@ export default class TestCaseRunner {
     if (this.shouldUpdateStatus(testStepResult)) {
       this.result.status = testStepResult.status
     }
+    if (testStepResult.exception) {
+      this.result.exception = testStepResult.exception
+    }
     this.emit('test-step-finished', {
       index: this.testStepIndex,
       result: testStepResult

src/runtime/test_case_runner_spec.js

@@ -217,7 +217,8 @@ describe('TestCaseRunner', function() {
         expect(this.onTestCaseFinished).to.have.been.calledWith({
           result: {
             duration: 1,
-            status: Status.FAILED
+            status: Status.FAILED,
+            exception: this.error
           },
           sourceLocation: { line: 1, uri: 'path/to/feature' }
         })
@@ -298,7 +299,14 @@ describe('TestCaseRunner', function() {
       it('emits test-case-finished', function() {
         expect(this.onTestCaseFinished).to.have.been.calledOnce
         expect(this.onTestCaseFinished).to.have.been.calledWith({
-          result: { duration: 0, status: Status.AMBIGUOUS },
+          result: {
+            duration: 0,
+            status: Status.AMBIGUOUS,
+            exception:
+              'Multiple step definitions match:\n' +
+              '  pattern1 - path/to/steps:3\n' +
+              '  pattern2 - path/to/steps:4'
+          },
           sourceLocation: { line: 1, uri: 'path/to/feature' }
         })
       })