Add mutation testing support with stryker

package.json

@@ -22,6 +22,10 @@
     "typescript": "^3.3.3"
   },
   "devDependencies": {
+    "@stryker-mutator/core": "^1.0.2",
+    "@stryker-mutator/jasmine-framework": "^1.0.2",
+    "@stryker-mutator/jasmine-runner": "^1.0.2",
+    "@stryker-mutator/typescript": "^1.0.2",
     "@types/jasmine": "^3.3.9",
     "jasmine": "^3.3.1",
     "jasmine-core": "^3.3.0",

spec/support/jasmine-stryker.json

+{
+  "spec_dir": "build/spec",
+  "spec_files": [
+    "**/*[sS]pec.js"
+  ],
+  "helpers": [
+    "helpers/**/*.js"
+  ],
+  "stopSpecOnExpectationFailure": false,
+  "random": true
+}

stryker.conf.js

+module.exports = function(config) {
+  config.set({
+    mutator: "typescript",
+    packageManager: "npm",
+    reporters: ["clear-text", "progress"],
+    testRunner: "jasmine",
+    transpilers: ["typescript"],
+    testFramework: "jasmine",
+    coverageAnalysis: "perTest",
+    jasmineConfigFile: "spec/support/jasmine-stryker.json",
+    tsconfigFile: "tsconfig.json",
+    mutate: ["src/move-validation.ts"]
+  });
+};