Breaking: Handle overwrite option in symlink to be consistent with dest

README.md

@@ -242,6 +242,14 @@ Type: `Number`
 
 Default: The process mode.
 
+##### `options.overwrite`
+
+Whether or not existing files with the same path should be overwritten. Can also be a function that takes in a file and returns `true` or `false`.
+
+Type: `Boolean` or `Function`
+
+Default: `true` (always overwrite existing files)
+
 ##### `options.relative`
 
 Whether or not the symlink should be relative or absolute.

lib/symlink/index.js

@@ -36,7 +36,7 @@ function symlink(outFolder, opt) {
     // * Most products CANNOT detect a directory is a Junction:
     //    This has the side effect of possibly having a whole directory
     //    deleted when a product is deleting the Junction directory.
-    //    For example, IntelliJ product lines will delete the entire
+    //    For example, JetBrains product lines will delete the entire
     //    contents of the TARGET directory because the product does not
     //    realize it's a symlink as the JVM and Node return false for isSymlink.
     var useJunctions = koalas(boolean(opt.useJunctions, file), (isWindows && isDirectory));
@@ -50,14 +50,42 @@ function symlink(outFolder, opt) {
       srcPath = path.relative(file.base, srcPath);
     }
 
-    fs.symlink(srcPath, file.path, symType, onSymlink);
+    // Because fs.symlink does not allow atomic overwrite option with flags, we
+    // delete and recreate if the link already exists and overwrite is true.
+    if (file.flag === 'w') {
+      // TODO What happens when we call unlink with windows junctions?
+      fs.unlink(file.path, onUnlink);
+    } else {
+      fs.symlink(srcPath, file.path, symType, onSymlink);
+    }
+
+    function onUnlink(unlinkErr) {
+      if (unlinkErr && unlinkErr.code !== 'ENOENT') {
+        return callback(unlinkErr);;
+      }
+      fs.symlink(srcPath, file.path, symType, onSymlink);
+    }
 
     function onSymlink(symlinkErr) {
       if (isErrorFatal(symlinkErr)) {
         return callback(symlinkErr);
       }
       callback(null, file);
     }
+
+    function isErrorFatal(err) {
+      if (!err) {
+        return false;
+      }
+
+      if (err.code === 'EEXIST' && file.flag === 'wx') {
+        // Handle scenario for file overwrite failures.
+        return false;
+      }
+
+      // Otherwise, this is a fatal error
+      return true;
+    }
   }
 
   var stream = pumpify.obj(
@@ -70,19 +98,4 @@ function symlink(outFolder, opt) {
   return lead(stream);
 }
 
-function isErrorFatal(err) {
-  if (!err) {
-    return false;
-  }
-
-  // TODO: should we check file.flag like .dest()?
-  if (err.code === 'EEXIST') {
-    // Handle scenario for file overwrite failures.
-    return false;
-  }
-
-  // Otherwise, this is a fatal error
-  return true;
-}
-
 module.exports = symlink;

test/symlink.js

@@ -542,6 +542,124 @@ describe('symlink stream', function() {
     ], assert);
   });
 
+  it('does not overwrite links with overwrite option set to false', function(done) {
+    var existingContents = 'Lorem Ipsum';
+
+    var file = new File({
+      base: inputBase,
+      path: inputPath,
+      contents: null,
+    });
+
+    function assert(files) {
+      var outputContents = fs.readFileSync(outputPath, 'utf8');
+
+      expect(files.length).toEqual(1);
+      expect(outputContents).toEqual(existingContents);
+    }
+
+    // Write expected file which should not be overwritten
+    fs.mkdirSync(outputBase);
+    fs.writeFileSync(outputPath, existingContents);
+
+    pipe([
+      from.obj([file]),
+      vfs.symlink(outputBase, { overwrite: false }),
+      concat(assert),
+    ], done);
+  });
+
+  it('overwrites links with overwrite option set to true', function(done) {
+    var existingContents = 'Lorem Ipsum';
+
+    var file = new File({
+      base: inputBase,
+      path: inputPath,
+      contents: null,
+    });
+
+    function assert(files) {
+      var outputContents = fs.readFileSync(outputPath, 'utf8');
+
+      expect(files.length).toEqual(1);
+      expect(outputContents).toEqual(contents);
+    }
+
+    // This should be overwritten
+    fs.mkdirSync(outputBase);
+    fs.writeFileSync(outputPath, existingContents);
+
+    pipe([
+      from.obj([file]),
+      vfs.symlink(outputBase, { overwrite: true }),
+      concat(assert),
+    ], done);
+  });
+
+  it('does not overwrite links with overwrite option set to a function that returns false', function(done) {
+    var existingContents = 'Lorem Ipsum';
+
+    var file = new File({
+      base: inputBase,
+      path: inputPath,
+      contents: null,
+    });
+
+    function overwrite(f) {
+      expect(f).toEqual(file);
+      return false;
+    }
+
+    function assert(files) {
+      var outputContents = fs.readFileSync(outputPath, 'utf8');
+
+      expect(files.length).toEqual(1);
+      expect(outputContents).toEqual(existingContents);
+    }
+
+    // Write expected file which should not be overwritten
+    fs.mkdirSync(outputBase);
+    fs.writeFileSync(outputPath, existingContents);
+
+    pipe([
+      from.obj([file]),
+      vfs.symlink(outputBase, { overwrite: overwrite }),
+      concat(assert),
+    ], done);
+  });
+
+  it('overwrites links with overwrite option set to a function that returns true', function(done) {
+    var existingContents = 'Lorem Ipsum';
+
+    var file = new File({
+      base: inputBase,
+      path: inputPath,
+      contents: null,
+    });
+
+    function overwrite(f) {
+      expect(f).toEqual(file);
+      return true;
+    }
+
+    function assert(files) {
+      var outputContents = fs.readFileSync(outputPath, 'utf8');
+
+      expect(files.length).toEqual(1);
+      expect(outputContents).toEqual(contents);
+    }
+
+    // This should be overwritten
+    fs.mkdirSync(outputBase);
+    fs.writeFileSync(outputPath, existingContents);
+
+    pipe([
+      from.obj([file]),
+      vfs.symlink(outputBase, { overwrite: overwrite }),
+      concat(assert),
+    ], done);
+  });
+
   it('emits an end event', function(done) {
     var symlinkStream = vfs.symlink(outputBase);