Test we've added a nonewline line

src/Renderer/Patch.hs

@@ -47,7 +47,7 @@ rowIncrement = fmap lineIncrement
 -- | Given the before and after sources, render a hunk to a string.
 showHunk :: Both SourceBlob -> Hunk (SplitDiff a Info) -> String
 showHunk blobs hunk = if last sourceHunk /= '\n'
-                      then sourceHunk ++ "\n\\ No newline at end of file\n"
+                      then sourceHunk ++ "\n\\\\ No newline at end of file\n"
                       else sourceHunk
   where sources = source <$> blobs
         sourceHunk = header blobs hunk ++ concat (showChange sources <$> changes hunk) ++ showLines (snd sources) ' ' (snd <$> trailingContext hunk)

test/diffs/no-newline-at-eof.A.js

@@ -0,0 +1 @@
+console.log("hello, world");

test/diffs/no-newline-at-eof.B.js

@@ -0,0 +1,3 @@
+console.log("hello, world");
+
+console.log("insertion");

test/diffs/no-newline-at-eof.patch.js

@@ -2,7 +2,8 @@ diff --git a/test/diffs/no-newline-at-eof.A.js b/test/diffs/no-newline-at-eof.B.
 index .. 100644
 --- a/test/diffs/no-newline-at-eof.A.js
 +++ b/test/diffs/no-newline-at-eof.B.js
-@@ -1,1 +1,3 @@
+@@ -1,2 +1,3 @@
  console.log("hello, world");
  
-+console.log("insertion");
++console.log("insertion");
+\\ No newline at end of file