Fix diffTrimmedLines not keep whitespaces in the output

src/diff/line.js

@@ -12,22 +12,60 @@ lineDiff.tokenize = function(value) {
   }
 
   // Merge the content and line separators into single tokens
-  for (let i = 0; i < linesAndNewlines.length; i++) {
-    let line = linesAndNewlines[i];
-
-    if (i % 2 && !this.options.newlineIsToken) {
-      retLines[retLines.length - 1] += line;
-    } else {
-      if (this.options.ignoreWhitespace) {
-        line = line.trim();
+  if (this.options.ignoreWhitespace) {
+    for (let i = 0; i < linesAndNewlines.length; i++) {
+      let line = linesAndNewlines[i];
+
+      if (i % 2 && !this.options.newlineIsToken) {
+        let last = retLines[retLines.length - 1];
+        last.key += line;
+        last.payload += line;
+      } else {
+        retLines.push({ key: line.trim(), payload: line });
+      }
+    }
+  } else {
+    for (let i = 0; i < linesAndNewlines.length; i++) {
+      let line = linesAndNewlines[i];
+
+      if (i % 2 && !this.options.newlineIsToken) {
+        retLines[retLines.length - 1] += line;
+      } else {
+        retLines.push(line);
       }
-      retLines.push(line);
     }
   }
 
   return retLines;
 };
 
+lineDiff.removeEmpty = function(array) {
+  if (this.options.ignoreWhitespace) {
+    return array.filter(v => v.key);
+  }
+  return array.filter(v => v);
+};
+
+lineDiff.equals = function(left, right) {
+  if (this.options.ignoreWhitespace) {
+    // Special case handle for when one terminal is ignored (i.e. whitespace).
+    // For this case we merge the terminal into the prior string and drop the change.
+    // This is only available for string mode.
+    if (left === '') {
+      return Diff.prototype.equals.call(this, left, right.trim());
+    }
+    return Diff.prototype.equals.call(this, left.key, right.key);
+  }
+  return Diff.prototype.equals.call(this, left, right);
+};
+
+lineDiff.join = function(result) {
+  if (this.options.ignoreWhitespace) {
+    return result.map(v => v.payload).join('');
+  }
+  return result.join('');
+};
+
 export function diffLines(oldStr, newStr, callback) { return lineDiff.diff(oldStr, newStr, callback); }
 export function diffTrimmedLines(oldStr, newStr, callback) {
   let options = generateOptions(callback, {ignoreWhitespace: true});

test/diff/line.js

@@ -64,17 +64,52 @@ describe('diff/line', function() {
     });
 
     it('should ignore leading and trailing whitespace', function() {
-      const diffResult = diffTrimmedLines(
+      const diffResult1 = diffTrimmedLines(
         'line\nvalue \nline',
         'line\nvalue\nline');
-      expect(convertChangesToXML(diffResult)).to.equal('line\nvalue\nline');
+      expect(convertChangesToXML(diffResult1)).to.equal('line\nvalue\nline');
+
+      const diffResult2 = diffTrimmedLines(
+        'line\nvalue\nline',
+        'line\nvalue \nline');
+      expect(convertChangesToXML(diffResult2)).to.equal('line\nvalue \nline');
+
+      const diffResult3 = diffTrimmedLines(
+        'line\n value\nline',
+        'line\nvalue\nline');
+      expect(convertChangesToXML(diffResult3)).to.equal('line\nvalue\nline');
+
+      const diffResult4 = diffTrimmedLines(
+        'line\nvalue\nline',
+        'line\n value\nline');
+      expect(convertChangesToXML(diffResult4)).to.equal('line\n value\nline');
+    });
+
+    it('should keep leading and trailing whitespace in the output', function() {
+      function stringify(value) {
+        return JSON.stringify(value, null, 2);
+      }
+      const diffResult = diffTrimmedLines(
+        stringify([10, 20, 30]),
+        stringify({ data: [10, 42, 30] }));
+      expect(convertChangesToXML(diffResult)).to.equal([
+        '<del>[\n</del>',
+        '<ins>{\n',
+        '  "data": [\n</ins>',
+        '    10,\n',
+        '<del>  20,\n</del>',
+        '<ins>    42,\n</ins>',
+        '    30\n',
+        '<del>]</del><ins>  ]\n',
+        '}</ins>'
+      ].join('').replace(/"/g, '&quot;'));
     });
 
     it('should handle windows line endings', function() {
       const diffResult = diffTrimmedLines(
         'line\r\nold value \r\nline',
         'line\r\nnew value\r\nline');
-      expect(convertChangesToXML(diffResult)).to.equal('line\r\n<del>old value\r\n</del><ins>new value\r\n</ins>line');
+      expect(convertChangesToXML(diffResult)).to.equal('line\r\n<del>old value \r\n</del><ins>new value\r\n</ins>line');
     });
   });