test: Add a test suite with 100% [brag] code coverage to AWSLambda handler (#2891)

* test: Add a test suite with 100% [brag] code coverage to AWSLambda handler

Author: kamilogorek

packages/serverless/.eslintrc.js

@@ -16,6 +16,15 @@ module.exports = {
         project: './tsconfig.json',
       },
     },
+    {
+      files: ['test/**'],
+      rules: {
+        'no-empty': 'off',
+        '@typescript-eslint/no-empty-function': 'off',
+        '@typescript-eslint/no-explicit-any': 'off',
+        '@typescript-eslint/no-non-null-assertion': 'off',
+      },
+    },
   ],
   rules: {
     '@typescript-eslint/no-var-requires': 'off',

packages/serverless/package.json

@@ -20,13 +20,14 @@
     "@sentry/node": "5.23.0",
     "@sentry/types": "5.23.0",
     "@sentry/utils": "5.23.0",
-    "@types/aws-lambda": "^8.10.62",
-    "@types/node": "^14.6.4",
     "tslib": "^1.9.3"
   },
   "devDependencies": {
     "@sentry-internal/eslint-config-sdk": "5.23.0",
+    "@types/aws-lambda": "^8.10.62",
+    "@types/node": "^14.6.4",
     "eslint": "7.6.0",
+    "jest": "^24.7.1",
     "npm-run-all": "^4.1.2",
     "prettier": "1.19.0",
     "rimraf": "^2.6.3",
@@ -51,5 +52,25 @@
     "test:watch": "jest --watch --passWithNoTests",
     "pack": "npm pack"
   },
-  "sideEffects": false
+  "sideEffects": false,
+  "jest": {
+    "collectCoverage": true,
+    "transform": {
+      "^.+\\.ts$": "ts-jest"
+    },
+    "moduleFileExtensions": [
+      "js",
+      "ts"
+    ],
+    "testEnvironment": "node",
+    "testMatch": [
+      "**/*.test.ts"
+    ],
+    "globals": {
+      "ts-jest": {
+        "tsConfig": "./tsconfig.json",
+        "diagnostics": false
+      }
+    }
+  }
 }

packages/serverless/src/awslambda.ts

@@ -165,10 +165,7 @@ export const wrapHandler = <TEvent = any, TResult = any>(
         if (args[0] === null || args[0] === undefined) {
           resolve(callback(...args));
         } else {
-          captureExceptionAsync(args[0], context, options).then(
-            () => reject(callback(...args)),
-            () => reject(callback(...args)),
-          );
+          captureExceptionAsync(args[0], context, options).finally(() => reject(callback(...args)));
         }
       };
     };

packages/serverless/test/.gitkeep

@@ -0,0 +1,26 @@
+export const SDK_VERSION = '6.6.6';
+export const Severity = {
+  Warning: 'warning',
+};
+export const fakeScope = {
+  addEventProcessor: jest.fn(),
+  setTransactionName: jest.fn(),
+  setTag: jest.fn(),
+  setContext: jest.fn(),
+};
+export const captureException = jest.fn();
+export const captureMessage = jest.fn();
+export const withScope = jest.fn(cb => cb(fakeScope));
+export const flush = jest.fn(() => Promise.resolve());
+
+export const resetMocks = (): void => {
+  fakeScope.addEventProcessor.mockClear();
+  fakeScope.setTransactionName.mockClear();
+  fakeScope.setTag.mockClear();
+  fakeScope.setContext.mockClear();
+
+  captureException.mockClear();
+  captureMessage.mockClear();
+  withScope.mockClear();
+  flush.mockClear();
+};