applyPatch affecting wrong line number with with new lines

[Luiz-N]

@kpdecker your library is great so far. I think I might have found an edge case unless i'm missing something?

oldString = 'test\ntest2\n \ntest3\n';
"test
test2
 
test3
"

newString = 'test\ntest2\ntest3\n';
"test
test2
test3
"

Now I create a patch

d = JsDiff.createPatch('file/path.js', oldString, newString, '', '', { context: 0 });

This patch/diff looks correct

"Index: file/path.js
===================================================================
--- file/path.js	
+++ file/path.js	
@@ -3,1 +3,0 @@
- 

However when I apply the patch....

result = JsDiff.applyPatch(oldString, d);
"test
test2
 
"

We can see it seems to be affecting the wrong line number. Is it trimming somewhere on the oldString where it shouldn't be?

[Luiz-N]

UPDATE:

I've narrowed the scope of the bug down to when context is set to 0. So by setting it to 1 or higher it works correctly:

d = JsDiff.createPatch('file/path.js', oldString, newString, '', '', { context: 1 });

result = JsDiff.applyPatch(oldString, d);
"test
test2
test3
"

[ibc]

Good catch. Same happens here.

[bp-dev]

Also having problems with empty lines in 3 cases.

1. a patch starting with a empty line of context such as

@ -92,6 +92,19 @@

         <div id="secondaryToolbar" class="secondaryToolbar hidden doorHangerRight">
           <div id="secondaryToolbarButtonContainer">
+            <button id="secondaryOnePageMode" class="secondaryToolbarButton onePageMode visibleLargeView" title="One Page Mode" tabindex="51" data-l10n-id="one_page_mode">

is not applied (and following blocks are applied in the wrong place as line numbers don't match anymore)

2. a patch containing an empty line of context: the diff after the empty line is ignored as parsing stops

@@ -26,19 +26,8 @@
     <meta name="viewport" content="width=device-width, initial-scale=1, maximum-scale=1">
     <meta name="google" content="notranslate">
     <meta http-equiv="X-UA-Compatible" content="IE=edge">
-    <title>PDF.js viewer</title>
-
-
-    <link rel="stylesheet" href="viewer.css">
-
-
-
-
-
-<!-- This snippet is used in production (included from viewer.html) -->
-<link rel="resource" type="application/l10n" href="locale/locale.properties">
-<script src="pdf.viewer.js"></script>

+<!-- == INSERTS == -->

   </head>

3. a patch with a trailing empty line at the end (added by a text editor or whatever) runs endlessly after simple correction of the 2 above and requires to be handled specifically.

Pull request #212 fixes those cases (as far as I can test, comparing on a limited number of real-life samples with the behaviour of the linux patch command, which I would consider a good reference)

[Luiz-N]

I think this got fixed with #212