feat(reporter): add mutationReportReady event

Add the `onMutationTestReportReady` reporter interface method.
The argument is the report that is compliant to the
[mutation-testing-report-schema](https://github.com/stryker-mutator/mutation-testing-elements/tree/master/packages/mutation-testing-report-schema)

packages/api/package.json

@@ -36,6 +36,7 @@
 		"tslib": "~1.9.3"
 	},
 	"devDependencies": {
+		"mutation-testing-report-schema": "^1.0.0",
 		"surrial": "~1.0.0",
 		"typed-inject": "~1.0.0"
 	}

packages/api/report.ts

@@ -1,6 +1,14 @@
+import * as mutationTestReportSchema from 'mutation-testing-report-schema/dist/src/api';
 export { default as Reporter } from './src/report/Reporter';
 export { default as MutantResult } from './src/report/MutantResult';
 export { default as MutantStatus } from './src/report/MutantStatus';
 export { default as SourceFile } from './src/report/SourceFile';
 export { default as MatchedMutant } from './src/report/MatchedMutant';
 export { default as ScoreResult } from './src/report/ScoreResult';
+export {
+  /**
+   * Types exported directly from mutation-testing-schema
+   * @see https://github.com/stryker-mutator/mutation-testing-elements/tree/master/packages/mutation-testing-report-schema
+   */
+  mutationTestReportSchema
+};

packages/api/src/report/Reporter.ts

@@ -2,6 +2,7 @@ import ScoreResult from './ScoreResult';
 import SourceFile from './SourceFile';
 import MutantResult from './MutantResult';
 import MatchedMutant from './MatchedMutant';
+import { MutationTestResult } from 'mutation-testing-report-schema';
 
 /**
  * Represents a reporter which can report during or after a Stryker run
@@ -44,6 +45,13 @@ interface Reporter {
    */
   onScoreCalculated?(score: ScoreResult): void;
 
+  /**
+   * Called when mutation testing is done
+   * @param report the mutation test result that is valid according to the mutation-testing-report-schema (json schema)
+   * @see https://github.com/stryker-mutator/mutation-testing-elements/tree/master/packages/mutation-testing-report-schema#mutation-testing-elements-schema
+   */
+  onMutationTestReportReady?(report: MutationTestResult): void;
+
   /**
    * Called when stryker wants to quit
    * Gives a reporter the ability to finish up any async tasks