Feature: Add methods for checking permissions

src/file.js

@@ -36,6 +36,14 @@ class File {
     return pathname.split(path.sep).length - 1;
   }
 
+  _access(permission) {
+    let hasPermission = true;
+
+    return fsp.accessAsync(this._pathname, permission)
+      .catch(() => hasPermission = false)
+      .then(() => hasPermission);
+  }
+
   isDirectorySync() {
     return this._getStatsSync().isDirectory();
   }
@@ -120,6 +128,18 @@ class File {
   sizeSync() {
     return this._getStatsSync().size;
   }
+
+  isWritable() {
+    return this._access(fs.W_OK);
+  }
+
+  isReadable() {
+    return this._access(fs.R_OK);
+  }
+
+  isExecutable() {
+    return this._access(fs.X_OK);
+  }
 }
 
 module.exports.create = (filename) => {

test/file.js

@@ -398,4 +398,50 @@ describe('File', () => {
       assert.equal(file.getName(), getAbsolutePath('dates/a.txt'));
     });
   });
+
+  describe('.isWritable', () => {
+    it('returns true when the file has write permission', () => {
+      const file = File.create(getAbsolutePath('justFiles/a.json'));
+      file.isWritable()
+        .then((isWritable) => {
+          assert.strictEqual(isWritable, true);
+        });
+    });
+
+    it('returns false when the file does not have write permission', () => {
+      const file = File.create(getAbsolutePath('permissions/notWritable.json'));
+      file.isWritable()
+        .then((isWritable) => {
+          assert.strictEqual(isWritable, false);
+        });
+    });
+  });
+
+  describe('.isReadable', () => {
+    it('returns true when the file has read permission', () => {
+      const file = File.create(getAbsolutePath('permissions/readWrite.json'));
+      file.isReadable()
+        .then((isReadable) => {
+          assert.strictEqual(isReadable, true);
+        });
+    });
+  });
+
+  describe('.isExecutable', () => {
+    it('returns true when the file has read permission', () => {
+      const file = File.create(getAbsolutePath('permissions/executable.sh'));
+      file.isReadable()
+        .then((isExecutable) => {
+          assert.strictEqual(isExecutable, true);
+        });
+    });
+
+    it('returns false when the file does not have read permission', () => {
+      const file = File.create(getAbsolutePath('permissions/notExecutable.sh'));
+      file.isExecutable()
+        .then((isExecutable) => {
+          assert.strictEqual(isExecutable, false);
+        });
+    });
+  });
 });