[POC/Proposal] Custom output defined by user

docs/output.md

@@ -13,6 +13,8 @@
 ]
 ```
 
+---
+
 ## `github`
 
 Create check run, post commit status and a detailed comment on your PR.
@@ -68,6 +70,8 @@ Post comment on PR
 
 <img src="../assets/pr-comment.png" alt="pr comment" height="300px" />
 
+---
+
 ## `json`
 
 Save raw results in json file.
@@ -100,3 +104,45 @@ Override default options
 type: `string` default: `bundlemon-results.json`
 
 Use custom file name for results.
+
+---
+
+## `custom`
+
+Use our own implementation to output or process results.
+
+### Example
+
+`path` option is required.
+
+```json
+"reportOutput": [
+  [
+    "custom",
+    {
+      "path": "custom-output.js"
+    }
+  ]
+]
+```
+
+In the root of your project create `custom-output.js`:
+
+```js
+// Function that accepts generated report as parameter
+const output = (report) => {
+  console.log(report);
+};
+
+module.exports = output;
+```
+
+TODO: Document report object structure.
+
+### Options
+
+#### `path`
+
+type: `string`
+
+Relative path to the js file exporting a function.

packages/bundlemon/src/main/outputs/outputs/custom.ts

@@ -0,0 +1,50 @@
+import * as yup from 'yup';
+import path from 'path';
+import { Report } from 'bundlemon-utils';
+import { createLogger } from '../../../common/logger';
+import { validateYup } from '../../utils/validationUtils';
+import type { Output, OutputInstance } from '../types';
+
+const NAME = 'custom';
+
+const logger = createLogger(`${NAME} output`);
+
+interface CustomOutputOptions {
+  path?: string;
+}
+interface NormalizedCustomOutputOptions {
+  path: string;
+}
+
+export type CustomOutputFunction = (results: Report) => any;
+
+function validateOptions(options: unknown): NormalizedCustomOutputOptions {
+  const schema: yup.SchemaOf<CustomOutputOptions, CustomOutputOptions> = yup.object().required().shape({
+    path: yup.string().required(),
+  });
+
+  const normalizedOptions = validateYup(schema, options, `${NAME} output`);
+  if (normalizedOptions === undefined) {
+    throw new Error(`validation error in output "${NAME}" options`);
+  }
+  return normalizedOptions as NormalizedCustomOutputOptions;
+}
+
+const output: Output = {
+  name: NAME,
+  create: ({ options }): OutputInstance | Promise<OutputInstance | undefined> | undefined => {
+    const normalizedOptions = validateOptions(options);
+
+    return {
+      generate: async (report: Report): Promise<void> => {
+        const resolvedPath = path.join(process.cwd(), normalizedOptions.path);
+        logger.debug(`Requiring ${resolvedPath}`);
+        // eslint-disable-next-line @typescript-eslint/no-var-requires
+        const customOutput = require(resolvedPath);
+        customOutput(report);
+      },
+    };
+  },
+};
+
+export default output;

packages/bundlemon/src/main/outputs/outputs/index.ts

@@ -2,9 +2,10 @@
 import consoleOutput from './console';
 import githubOutput from './github';
 import jsonOutput from './json';
+import customOutput from './custom';
 
 import type { Output } from '../types';
 
-const outputs: Output[] = [consoleOutput, githubOutput, jsonOutput];
+const outputs: Output[] = [consoleOutput, githubOutput, jsonOutput, customOutput];
 
 export const getAllOutputs = (): Output[] => outputs;