Add a util for converting patches between Windows & Unix line endings

src/patch/line-endings.js

@@ -0,0 +1,19 @@
+export function unixToWin(patch) {
+  return patch.map(index => ({
+    ...index,
+    hunks: index.hunks.map(hunk => ({
+      ...hunk,
+      lines: hunk.lines.map(line => line.endsWith('\r') ? line : line + '\r')
+    }))
+  }));
+}
+
+export function winToUnix(patch) {
+  return patch.map(index => ({
+    ...index,
+    hunks: index.hunks.map(hunk => ({
+      ...hunk,
+      lines: hunk.lines.map(line => line.endsWith('\r') ? line.substring(0, line.length - 1) : line)
+    }))
+  }));
+}

test/patch/line-endings.js

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+import {parsePatch} from '../../lib/patch/parse';
+import {formatPatch} from '../../lib/patch/create';
+import {winToUnix, unixToWin} from '../../lib/patch/line-endings';
+
+import {expect} from 'chai';
+
+describe('unixToWin and winToUnix', function() {
+  it('should convert line endings in a patch between Unix-style and Windows-style', function() {
+    const patch = parsePatch(
+      'Index: test\n'
+      + '===================================================================\n'
+      + '--- test\theader1\n'
+      + '+++ test\theader2\n'
+      + '@@ -1,3 +1,4 @@\n'
+      + ' line2\n'
+      + ' line3\r\n'
+      + '+line4\r\n'
+      + ' line5\n'
+    );
+
+    const winPatch = unixToWin(patch);
+    expect(formatPatch(winPatch)).to.equal(
+      'Index: test\n'
+      + '===================================================================\n'
+      + '--- test\theader1\n'
+      + '+++ test\theader2\n'
+      + '@@ -1,3 +1,4 @@\n'
+      + ' line2\r\n'
+      + ' line3\r\n'
+      + '+line4\r\n'
+      + ' line5\r\n'
+    );
+
+    const unixPatch = winToUnix(winPatch);
+    expect(formatPatch(unixPatch)).to.equal(
+      'Index: test\n'
+      + '===================================================================\n'
+      + '--- test\theader1\n'
+      + '+++ test\theader2\n'
+      + '@@ -1,3 +1,4 @@\n'
+      + ' line2\n'
+      + ' line3\n'
+      + '+line4\n'
+      + ' line5\n'
+    );
+  });
+});