Ignore unexpected content outside of strict mode

Fixes #76

Author: kpdecker

src/patch/parse.js

@@ -7,6 +7,14 @@ export function parsePatch(uniDiff, options = {}) {
     let index = {};
     list.push(index);
 
+    // Ignore any leading junk
+    while (i < diffstr.length) {
+      if ((/^Index:/.test(diffstr[i])) || (/^@@/.test(diffstr[i]))) {
+        break;
+      }
+      i++;
+    }
+
     let header = (/^Index: (.*)/.exec(diffstr[i]));
     if (header) {
       index.index = header[1];
@@ -31,10 +39,11 @@ export function parsePatch(uniDiff, options = {}) {
         break;
       } else if (/^@@/.test(diffstr[i])) {
         index.hunks.push(parseHunk());
-      } else if (!diffstr[i]) {
-        i++;
-      } else {
+      } else if (diffstr[i] && options.strict) {
+        // Ignore unexpected content unless in strict mode
         throw new Error('Unknown line ' + (i + 1) + ' ' + JSON.stringify(diffstr[i]));
+      } else {
+        i++;
       }
     }
   }

test/patch/parse.js

@@ -238,9 +238,17 @@ Index: test2
         parsePatch(`@@ -1,4 +1 @@`, {strict: true});
       }).to['throw']('Removed line count did not match for hunk at line 1');
     });
-    it('should throw on invalid input', function() {
+
+    it('should not throw on invalid input', function() {
+      expect(parsePatch('blit\nblat\nIndex: foo\nfoo'))
+          .to.eql([{
+            hunks: [],
+            index: 'foo'
+          }]);
+    });
+    it('should throw on invalid input in strict mode', function() {
       expect(function() {
-        parsePatch('Index: foo\nfoo');
+        parsePatch('Index: foo\nfoo', {strict: true});
       }).to['throw'](/Unknown line 2 "foo"/);
     });
   });