preExisting sourceMapping checks to not modify the original file

.gitignore

@@ -4,3 +4,4 @@ reports
 *.tgz
 .idea
 *.lock
+tmp

package.json

@@ -34,9 +34,11 @@
   "devDependencies": {
     "coveralls": "2.X",
     "faucet": "0.0.X",
+    "gulp": "3.X",
     "hook-std": "0.2.X",
     "istanbul": "0.X",
     "jshint": "2.X",
+    "object-assign": "^4.1.0",
     "tape": "4.X"
   },
   "files": [

src/init.js

@@ -40,6 +40,7 @@ function init(options) {
 
     var fileContent = file.contents.toString();
     var sourceMap;
+    var preExisting = utils.getPreExisting(fileContent);
 
     if (options.loadMaps) {
       debug('loadMaps');
@@ -113,11 +114,11 @@ function init(options) {
               }
             sourceMap.sourcesContent[i] = sourceContent;
           }
-        });
 
-        // remove source map comment from source
-        file.contents = new Buffer(fileContent, 'utf8');
+        });
       }
+      // remove source map comment from source
+      file.contents = new Buffer(fileContent, 'utf8');
     }
 
     if (!sourceMap && options.identityMap) {
@@ -199,6 +200,8 @@ function init(options) {
         sourcesContent: [fileContent]
       };
     }
+    else if(preExisting !== null && typeof preExisting !== 'undefined')
+      sourceMap.preExisting = preExisting
 
     sourceMap.file = unixStylePath(file.relative);
     file.sourceMap = sourceMap;

src/utils.js

@@ -1,5 +1,6 @@
 'use strict';
-var path = require('path');
+var path = require('path'),
+  detectNewline = require('detect-newline');
 
 function unixStylePath(filePath) {
   return filePath.split(path.sep).join('/');
@@ -9,8 +10,59 @@ var PLUGIN_NAME = require('../package.json').name;
 
 var urlRegex = /^(https?|webpack(-[^:]+)?):\/\//;
 
+var debug = require('debug-fabulous')()(PLUGIN_NAME + ':utils');
+
+var sourceMapUrlRegEx = /\/\/\# sourceMappingURL\=.*/g
+
+
+var getCommentFormatter = function (file) {
+  var extension = file.relative.split('.').pop(),
+    fileContents =  file.contents.toString(),
+    newline =  detectNewline.graceful(fileContents || ''),
+    commentFormatter = function(url) {
+      return '';
+    };
+
+  if (file.sourceMap.preExisting){
+    debug('preExisting commentFormatter');
+    commentFormatter = function(url) {
+      return file.sourceMap.preExisting;
+    };
+    return commentFormatter
+  }
+
+  switch (extension) {
+    case 'css':
+      debug('css commentFormatter');
+      commentFormatter = function(url) {
+        return newline + "/*# sourceMappingURL=" + url + " */" + newline;
+      };
+      break;
+    case 'js':
+      debug('js commentFormatter');
+      commentFormatter = function(url) {
+        return newline + "//# sourceMappingURL=" + url + newline;
+      };
+      break;
+    default:
+      debug('unknown commentFormatter')
+  }
+
+  return commentFormatter;
+}
+
+var getPreExisting = function(fileContent){
+  if(sourceMapUrlRegEx.test(fileContent)){
+    debug('has preExisting');
+    return fileContent.match(sourceMapUrlRegEx)[0];
+  }
+}
+
 module.exports = {
   unixStylePath: unixStylePath,
   PLUGIN_NAME: PLUGIN_NAME,
-  urlRegex: urlRegex
+  urlRegex: urlRegex,
+  sourceMapUrlRegEx: sourceMapUrlRegEx,
+  getCommentFormatter: getCommentFormatter,
+  getPreExisting: getPreExisting
 };

src/write.js

@@ -6,8 +6,7 @@ var utils = require('./utils'),
   fs = require('graceful-fs'),
   path = require('path'),
   File = require('vinyl'),
-  stripBom = require('strip-bom'),
-  detectNewline = require('detect-newline');
+  stripBom = require('strip-bom');
 
 /**
  * Write the source map
@@ -92,34 +91,13 @@ function write(destPath, options) {
       delete sourceMap.sourcesContent;
     }
 
-    var extension = file.relative.split('.').pop();
-    var newline = detectNewline.graceful(file.contents.toString());
-    var commentFormatter;
-
-    switch (extension) {
-      case 'css':
-        commentFormatter = function(url) {
-          return newline + "/*# sourceMappingURL=" + url + " */" + newline;
-        };
-        break;
-      case 'js':
-        commentFormatter = function(url) {
-          return newline + "//# sourceMappingURL=" + url + newline;
-        };
-        break;
-      default:
-        /* jshint ignore:start */
-        commentFormatter = function(url) {
-          return "";
-        };
-        /* jshint ignore:end */
-    }
-
-    var comment;
+    var comment,
+      commentFormatter = utils.getCommentFormatter(file);
 
     if (destPath === undefined || destPath === null) {
       // encode source map into comment
       var base64Map = new Buffer(JSON.stringify(sourceMap)).toString('base64');
+      debug("basic comment")
       comment = commentFormatter('data:application/json;charset=' + options.charset + ';base64,' + base64Map);
     } else {
       var mapFile = path.join(destPath, file.relative) + '.map';
@@ -174,16 +152,23 @@ function write(destPath, options) {
         }
         sourceMapPathRelative = prefix + path.join('/', sourceMapPathRelative);
       }
+      debug("destPath comment")
       comment = commentFormatter(unixStylePath(sourceMapPathRelative));
 
       if (options.sourceMappingURL && typeof options.sourceMappingURL === 'function') {
+        debug("options.sourceMappingURL comment")
         comment = commentFormatter(options.sourceMappingURL(file));
       }
     }
 
     // append source map comment
-    if (options.addComment)
-      file.contents = Buffer.concat([file.contents, new Buffer(comment)]);
+    if (options.addComment){
+      if(options.preExisting && utils.getPreExisting(String(file.contents))){
+        //normally the comment is pre-stripped but this option lets us know it is not
+      }
+      else
+        file.contents = Buffer.concat([file.contents, new Buffer(comment)]);
+    }
 
     this.push(file);
     callback();

test/init.js

@@ -164,6 +164,7 @@ test('init: should import an existing inline source map', function(t) {
     t.ok(data, 'should pass something through');
     t.ok(data instanceof File, 'should pass a vinyl file through');
     t.ok(data.sourceMap, 'should add a source map object');
+    t.notOk(/sourceMappingURL/.test(data.contents.toString()), 'should not have sourcemapping in data.contents');
     t.equal(String(data.sourceMap.version), '3', 'should have version 3');
     t.deepEqual(data.sourceMap.sources, [
       'test1.js', 'test2.js'
@@ -179,14 +180,6 @@ test('init: should import an existing inline source map', function(t) {
   }).write(makeFileWithInlineSourceMap());
 });
 
-test('init: should remove inline sourcemap', function(t) {
-  var pipeline = sourcemaps.init({loadMaps: true});
-  pipeline.on('data', function(data) {
-    t.notOk(/sourceMappingURL/.test(data.contents.toString()), 'should not have sourcemapping');
-    t.end();
-  }).write(makeFileWithInlineSourceMap());
-});
-
 test('init: should load external source map file referenced in comment with the \/\/# syntax', function(t) {
   var file = makeFile();
   file.contents = new Buffer(sourceContent + '\n//# sourceMappingURL=helloworld2.js.map');
@@ -400,10 +393,16 @@ test('init: should output an error message if debug option is set and sourceCont
 
   pipeline.on('data', function() {
     unhook();
-    // debug.save(null);
-    t.ok(history.length == 4, 'history len');
-    t.ok(history[2].match(/No source content for \"missingfile\". Loading from file./), 'should log missing source content');
-    t.ok(history[3].match(/source file not found: /), 'should warn about missing file');
+    var hasRegex =  function(regex){
+      return function(s){
+        return regex.test(s);
+      };
+    };
+    t.ok(
+      history.some(
+        hasRegex(/No source content for \"missingfile\". Loading from file./)),
+      'should log missing source content');
+    t.ok(history.some(hasRegex(/source file not found: /)), 'should warn about missing file');
     t.end();
   }).write(file);
 

test/integration.js

@@ -0,0 +1,59 @@
+'use strict';
+var gulp = require('gulp');
+var test = require('tape');
+var $ = require('..');
+var PLUGIN_NAME = require('../src/utils').PLUGIN_NAME;
+var debug = require('debug-fabulous')()(PLUGIN_NAME + ':test:integration');
+var join = require('path').join;
+var fs = require('fs');
+var sourceContent = fs.readFileSync(join(__dirname, 'assets/helloworld.js')).toString();
+
+debug('running');
+
+test('creates inline mapping', function(t) {
+
+  gulp.src(join(__dirname, './assets/helloworld.js'))
+  .pipe($.init())
+  .pipe($.write())
+  // .pipe(gulp.dest('tmp'))
+  .on('data', function(data) {
+    t.ok(data.sourceMap, 'should add a source map object');
+    t.deepEqual(
+      data.contents.toString(),
+      sourceContent + "\n//# sourceMappingURL=data:application/json;charset=utf8;base64,eyJ2ZXJzaW9uIjozLCJuYW1lcyI6W10sIm1hcHBpbmdzIjoiIiwic291cmNlcyI6WyJoZWxsb3dvcmxkLmpzIl0sInNvdXJjZXNDb250ZW50IjpbIid1c2Ugc3RyaWN0JztcblxuZnVuY3Rpb24gaGVsbG9Xb3JsZCgpIHtcbiAgICBjb25zb2xlLmxvZygnSGVsbG8gd29ybGQhJyk7XG59XG4iXSwiZmlsZSI6ImhlbGxvd29ybGQuanMifQ==\n",
+      'file should be sourcemapped'
+    );
+    t.end();
+  })
+  .on('error', function() {
+    t.fail('emitted error');
+    t.end();
+  })
+  .on('close', function() {
+    t.end();
+  });
+});
+
+test('creates re-uses existing mapping', function(t) {
+  gulp.src(join(__dirname, './assets/helloworld.map.js'))
+  .pipe($.init({loadMaps:true}))
+  .pipe($.write())
+  // .pipe(gulp.dest('tmp'))
+  .on('data', function(data) {
+    t.ok(data.sourceMap, 'should add a source map object');
+    t.ok(!!data.sourceMap.preExisting, 'should know the sourcemap pre-existed');
+    t.deepEqual(
+      data.contents.toString(),
+      sourceContent + "\n//# sourceMappingURL=data:application/json;charset=utf8;base64,eyJ2ZXJzaW9uIjozLCJuYW1lcyI6W10sIm1hcHBpbmdzIjoiIiwic291cmNlcyI6WyJoZWxsb3dvcmxkLmpzIl0sInNvdXJjZXNDb250ZW50IjpbIid1c2Ugc3RyaWN0JztcblxuZnVuY3Rpb24gaGVsbG9Xb3JsZCgpIHtcbiAgICBjb25zb2xlLmxvZygnSGVsbG8gd29ybGQhJyk7XG59XG4iXSwiZmlsZSI6ImhlbGxvd29ybGQuanMifQ==",
+      'file should be sourcemapped'
+    );
+    t.end();
+  })
+  .on('error', function() {
+    t.fail('emitted error');
+    t.end();
+  })
+  .on('close', function() {
+    t.end();
+  });
+});