fix: properly handle rejected promises in utils (#130) (#126)

Resolves #126

Author: DavidParks8

.gitignore

@@ -5,6 +5,10 @@ npm-debug.log*
 yarn-debug.log*
 yarn-error.log*
 
+# IDE temp data
+/.vs
+/.idea
+
 # Runtime data
 pids
 *.pid

src/lib/util/copy.ts

@@ -1,27 +1,14 @@
+import { promisify } from './promisify';
 const cpx = require('cpx');
 
-export const copyFiles = (src: string, dest: string, options?: any): Promise<any> => {
-
-  return new Promise((resolve, reject) => {
+export const copyFiles = (src: string, dest: string, options?: any): Promise<void> => {
 
+  return promisify<void>((resolveOrReject) => {
     if (options) {
-      cpx.copy(src, dest, options, (err) => {
-        if (err) {
-          reject();
-        }
-
-        resolve();
-      });
+      cpx.copy(src, dest, options, resolveOrReject);
     } else {
-      cpx.copy(src, dest, (err) => {
-        if (err) {
-          reject();
-        }
-
-        resolve();
-      });
+      cpx.copy(src, dest, resolveOrReject);
     }
-
   });
 
-}
+};

src/lib/util/fs.ts

@@ -1,32 +1,32 @@
 import * as fs from 'fs';
 import * as path from 'path';
 const read = require('read-file');
+import { promisify } from './promisify';
 
 export const readFile = (file: string): Promise<string> => {
 
-  return new Promise((resolve, reject) => {
-
-    read(file, { encoding: 'utf8', normalize: true }, (err, buffer: Buffer) => {
-      if (err) {
-        reject(err);
+  return promisify<string>((resolveOrReject) => {
+    const fileReadOptions = {
+      encoding: 'utf8',
+      normalize: true
+    };
+    read(file, fileReadOptions, (err, buffer?: Buffer) => {
+      if (buffer) {
+        resolveOrReject(err, buffer.toString());
+      } else {
+        resolveOrReject(err);
       }
-
-      resolve(buffer.toString());
     });
   });
+
 };
 
-export const writeFile = (file: string, content: any): Promise<any> => {
+export const writeFile = (file: string, content: any): Promise<string> => {
 
-  return new Promise((resolve, reject) => {
-    fs.writeFile(file, content, (err) => {
-      if (err) {
-        reject(err);
-      }
-
-      resolve();
-    });
+  return promisify<string>((resolveOrReject) => {
+    fs.writeFile(file, content, resolveOrReject);
   });
+
 };
 
 

src/lib/util/json.ts

@@ -1,5 +1,6 @@
 const glob = require('glob')
-import { readFile, writeFile } from '../util/fs';
+import { readFile, writeFile } from './fs';
+import { promisify } from './promisify';
 
 /**
  * Reads a JSON file.
@@ -25,25 +26,23 @@ export const writeJson = (object: any, file: string): Promise<any> =>
  * Modifies a set of JSON files by invoking `modifyFn`
  *
  * @param globPattern A glob pattern matching several files. Example: '**\/*.js.map'
- * @param modifyFn A callback function that tajes a JSON-parsed input and should return an output
+ * @param modifyFn A callback function that takes a JSON-parsed input and should return an output
  *                  that will be JSON-stringified
  */
 export const modifyJsonFiles = (globPattern: string, modifyFn: (jsonObj: any) => any): Promise<void> => {
 
-  return new Promise<string[]>((resolve, reject) => {
-      glob(globPattern, (err, files: string[]) => {
-        if (err) {
-          reject(err);
-        }
-
-        resolve(files);
-      });
-    })
-    .then((fileNames: string[]): Promise<string[]> => Promise.all(
-      fileNames.map((fileName: string): Promise<string> => readFile(fileName)
-        .then((fileContent: string) => writeFile(fileName, JSON.stringify(modifyFn(JSON.parse(fileContent)))))
+  return promisify<string[]>((resolveOrReject) => {
+    glob(globPattern, resolveOrReject);
+  })
+  .then((fileNames: string[]): Promise<string[]> =>
+    Promise.all(
+      fileNames.map((fileName: string): Promise<string> =>
+        readFile(fileName)
+          .then((fileContent: string) =>
+            writeFile(fileName, JSON.stringify(modifyFn(JSON.parse(fileContent))))
+          )
       ))
     )
-    .then(() => Promise.resolve());
+  .then(() => Promise.resolve());
 
 };

src/lib/util/promisify.ts

@@ -0,0 +1,14 @@
+
+export type PromiseCallback<T> = (err: Error, value?: T) => void;
+
+export function promisify<T>(resolver: (resolveOrReject: PromiseCallback<T>) => void): Promise<T> {
+  return new Promise<T>((resolve, reject) => {
+    resolver(((err: Error, value?: T): void => {
+      if (err) {
+        reject(err);
+      } else {
+        resolve(value);
+      }
+    }))
+  });
+}

src/lib/util/rimraf.ts

@@ -1,29 +1,16 @@
 const rm = require('rimraf');
-import { debug } from '../util/log';
+import { promisify } from './promisify';
+import { debug } from './log';
 
 export const rimraf = (f: any, opts?: any) => {
+  debug(`rimraf ${f}`);
 
-  return new Promise((resolve, reject) => {
-    debug(`rimraf ${f}`);
-
+  return promisify<void>((resolveOrReject) => {
     if (opts) {
-      rm(f, opts, (err) => {
-        if (err) {
-          reject(err);
-        }
-
-        resolve();
-      });
+      rm(f, opts, resolveOrReject);
     } else {
-      rm(f, (err) => {
-        if (err) {
-          reject(err);
-        }
-
-        resolve();
-      });
+      rm(f, resolveOrReject);
     }
-
   });
 
-}
+};