Add appendToFile (#4)

Feature: appendToFile: Issue #1

Author: niccord

README.md

@@ -29,13 +29,13 @@ fue.readDirectoryFiles('path/')
 
 ```
 
-
 ## API
 
 
 * [file-utils-easy](#module_file-utils-easy)
     * [~writeToFile(fileContent, filePath)](#module_file-utils-easy..writeToFile) ⇒ <code>Promise.&lt;string&gt;</code>
     * [~writeToFileStream(fileStream, filePath)](#module_file-utils-easy..writeToFileStream) ⇒ <code>Promise</code>
+    * [~appendToFile(fileContent, filePath)](#module_file-utils-easy..appendToFile) ⇒ <code>Promise.&lt;string&gt;</code>
     * [~readFileStats(filePath)](#module_file-utils-easy..readFileStats) ⇒ <code>Promise.&lt;fs.Stats&gt;</code>
     * [~readDirectoryFiles(directory)](#module_file-utils-easy..readDirectoryFiles) ⇒ <code>Promise.&lt;array&gt;</code>
     * [~readFile(filePath, [encoding])](#module_file-utils-easy..readFile) ⇒ <code>Promise.&lt;string&gt;</code>
@@ -73,6 +73,19 @@ Write a stream to a file
 | fileStream | <code>stream</code> | the stream payload |
 | filePath | <code>string</code> | path and filename: where store the file |
 
+<a name="module_file-utils-easy..appendToFile"></a>
+
+### file-utils-easy~appendToFile(fileContent, filePath) ⇒ <code>Promise.&lt;string&gt;</code>
+Append a string to a file
+
+**Kind**: inner method of [<code>file-utils-easy</code>](#module_file-utils-easy)  
+**Returns**: <code>Promise.&lt;string&gt;</code> - resolve with the filePath received in input  
+
+| Param | Type | Description |
+| --- | --- | --- |
+| fileContent | <code>string</code> | the payload of the file |
+| filePath | <code>string</code> | path and filename: where store the file |
+
 <a name="module_file-utils-easy..readFileStats"></a>
 
 ### file-utils-easy~readFileStats(filePath) ⇒ <code>Promise.&lt;fs.Stats&gt;</code>
@@ -203,7 +216,6 @@ Check if a file exists
 | filePath | <code>string</code> | path and filename: the file to control |
 
 
-
 ## Test
 
 For run the tests simply execute:

index.js

@@ -28,6 +28,24 @@ function writeToFile(fileContent, filePath) {
   });
 }
 
+/**
+ * Append a string to a file, if the file doesn't exist it is created
+ * @param {string} fileContent the payload of the file
+ * @param {string} filePath path and filename: where store the file
+ * @returns {Promise<string>} resolve with the filePath received in input
+ */
+function appendToFile(fileContent, filePath) {
+  return new Promise((resolve, reject) => {
+    fs.appendFile(filePath, fileContent, 'utf8', (err) => {
+      if (err) {
+        reject(err);
+      } else {
+        resolve(filePath);
+      }
+    });
+  });
+}
+
 
 /**
  * Write a stream to a file
@@ -239,6 +257,7 @@ function existFile(filePath, mode = fs.constants.W_OK) {
 
 module.exports = Object.freeze({
   writeToFile,
+  appendToFile,
   writeToFileStream,
   readDirectoryFiles,
   readFile,

test/assets/append.txt

@@ -0,0 +1 @@
+Hello world - this is some added text

test/file-utils-easy.test.js

@@ -35,6 +35,35 @@ describe('write tests', () => {
   });
 });
 
+describe('append tests', () => {  
+  it('create with append relative', async () => {
+    const fileContent = 'Hello world';
+    const filePath = 'test/assets/append.txt';
+    try {
+      await fue.deleteFile(filePath);
+    } catch (err) { }
+    return expect(fue.appendToFile(fileContent, filePath)).resolves.toEqual(filePath);
+  });
+  
+  it('append relative', async () => {
+    const fileContent = 'Hello world';
+    const filePath = 'test/assets/append.txt';
+    const addingContent = ' - this is some added text';
+    try {
+      await fue.deleteFile(filePath);
+    } catch (err) { }
+    const res = await fue.writeToFile(fileContent, filePath).then(fp => fue.appendToFile(addingContent, fp));
+    expect(res).toEqual(filePath);
+    return expect(fue.readFile(filePath)).resolves.toEqual(fileContent + addingContent);
+  });
+
+  it('append in not existing path', () => {
+    const fileContent = 'Hello world';
+    const filePath = 'output/not-exist.txt';
+    return expect(fue.appendToFile(fileContent, filePath))
+      .rejects.toBeDefined();
+  });
+});
 
 describe('alter tests', () => {
   it('rename file to existing path', () => {
@@ -117,12 +146,11 @@ describe('delete tests', () => {
   });
 });
 
-
 describe('read tests', () => {
   it('file list', () => {
     const path = 'test/assets/';
     return expect(fue.readDirectoryFiles(path))
-      .resolves.toHaveLength(3);
+      .resolves.toHaveLength(4);
   });
 
   it('file list not existing path', () => {