Fix git diff with renames and hunk headers

When we have the file names we consider that the file is already past
the hunk header (@@) and since the renames were setting the names
before the diff was confused.
To fix this I kind of hacked a solution that only uses the rename
file paths if there is no hunk header comming.
We need to find a better way to decide when to start new hunk, finish
files etc

src/diff-parser.js

@@ -38,26 +38,26 @@
     var hunkHeaderPrefix = '@@';
 
     /* Add previous block(if exists) before start a new file */
-    var saveBlock = function() {
+    function saveBlock() {
       if (currentBlock) {
         currentFile.blocks.push(currentBlock);
         currentBlock = null;
       }
-    };
+    }
 
     /*
      * Add previous file(if exists) before start a new one
      * if it has name (to avoid binary files errors)
      */
-    var saveFile = function() {
+    function saveFile() {
       if (currentFile && currentFile.newName) {
         files.push(currentFile);
         currentFile = null;
       }
-    };
+    }
 
     /* Create file structure */
-    var startFile = function() {
+    function startFile() {
       saveBlock();
       saveFile();
 
@@ -65,9 +65,9 @@
       currentFile.blocks = [];
       currentFile.deletedLines = 0;
       currentFile.addedLines = 0;
-    };
+    }
 
-    var startBlock = function(line) {
+    function startBlock(line) {
       saveBlock();
 
       var values;
@@ -112,9 +112,9 @@
       currentBlock.oldStartLine2 = oldLine2;
       currentBlock.newStartLine = newLine;
       currentBlock.header = line;
-    };
+    }
 
-    var createLine = function(line) {
+    function createLine(line) {
       var currentLine = {};
       currentLine.content = line;
 
@@ -145,7 +145,34 @@
 
         currentBlock.lines.push(currentLine);
       }
-    };
+    }
+
+    /*
+     * Checks if there is a hunk header coming before a new file starts
+     *
+     * Hunk header is a group of three lines started by ( `--- ` , `+++ ` , `@@` )
+     */
+    function existHunkHeader(line, lineIdx) {
+      var idx = lineIdx;
+
+      while (idx < diffLines.length - 3) {
+        if (utils.startsWith(line, 'diff')) {
+          return false;
+        }
+
+        if (
+          utils.startsWith(diffLines[idx], oldFileNameHeader) &&
+          utils.startsWith(diffLines[idx + 1], newFileNameHeader) &&
+          utils.startsWith(diffLines[idx + 2], hunkHeaderPrefix)
+        ) {
+          return true;
+        }
+
+        idx++;
+      }
+
+      return false;
+    }
 
     var diffLines =
       diffInput.replace(/\\ No newline at end of file/g, '')
@@ -261,6 +288,8 @@
         return;
       }
 
+      var doesNotExistHunkHeader = !existHunkHeader(line, lineIndex);
+
       /*
        * Git diffs provide more information regarding files modes, renames, copies,
        * commits between changes and similarity indexes
@@ -276,16 +305,24 @@
         currentFile.newFileMode = values[1];
         currentFile.isNew = true;
       } else if ((values = copyFrom.exec(line))) {
+        if (doesNotExistHunkHeader) {
           currentFile.oldName = values[1];
+        }
         currentFile.isCopy = true;
       } else if ((values = copyTo.exec(line))) {
+        if (doesNotExistHunkHeader) {
           currentFile.newName = values[1];
+        }
         currentFile.isCopy = true;
       } else if ((values = renameFrom.exec(line))) {
+        if (doesNotExistHunkHeader) {
           currentFile.oldName = values[1];
+        }
         currentFile.isRename = true;
       } else if ((values = renameTo.exec(line))) {
+        if (doesNotExistHunkHeader) {
           currentFile.newName = values[1];
+        }
         currentFile.isRename = true;
       } else if ((values = similarityIndex.exec(line))) {
         currentFile.unchangedPercentage = values[1];

test/diff-parser-tests.js

@@ -543,5 +543,37 @@ describe('DiffParser', function() {
       assert.equal('Binary files differ', file1.blocks[0].header);
     });
 
+    it('should parse diff with --find-renames', function() {
+      var diff =
+        'diff --git a/src/test-bar.js b/src/test-baz.js\n' +
+        'similarity index 98%\n' +
+        'rename from src/test-bar.js\n' +
+        'rename to src/test-baz.js\n' +
+        'index e01513b..f14a870 100644\n' +
+        '--- a/src/test-bar.js\n' +
+        '+++ b/src/test-baz.js\n' +
+        '@@ -1,4 +1,32 @@\n' +
+        ' function foo() {\n' +
+        '-var bar = "Whoops!";\n' +
+        '+var baz = "Whoops!";\n' +
+        ' }\n' +
+        ' ';
+
+      var result = DiffParser.generateDiffJson(diff);
+      var file1 = result[0];
+      assert.equal(1, result.length);
+      assert.equal(1, file1.addedLines);
+      assert.equal(1, file1.deletedLines);
+      assert.equal('src/test-bar.js', file1.oldName);
+      assert.equal('src/test-baz.js', file1.newName);
+      assert.equal(1, file1.blocks.length);
+      assert.equal(5, file1.blocks[0].lines.length);
+      var linesContent = file1.blocks[0].lines.map(function(line) {
+        return line.content;
+      });
+      assert.deepEqual(linesContent,
+        [' function foo() {', '-var bar = "Whoops!";', '+var baz = "Whoops!";', ' }', ' ']);
+    });
+
   });
 });