1 files changed, 163 insertions, 0 deletions
diff --git a/spec/frontend/ide/lib/create_file_diff_spec.js b/spec/frontend/ide/lib/create_file_diff_spec.js
new file mode 100644
index 00000000000..4b428468a6d
--- /dev/null
+++ b/spec/frontend/ide/lib/create_file_diff_spec.js
@@ -0,0 +1,163 @@
+import createFileDiff from '~/ide/lib/create_file_diff';
+import { commitActionTypes } from '~/ide/constants';
+import {
+  createUpdatedFile,
+  createNewFile,
+  createMovedFile,
+  createDeletedFile,
+} from '../file_helpers';
+
+const PATH = 'test/numbers.md';
+const PATH_FOO = 'test/foo.md';
+const TEXT_LINE_COUNT = 100;
+const TEXT = Array(TEXT_LINE_COUNT)
+  .fill(0)
+  .map((_, idx) => `${idx + 1}`)
+  .join('\n');
+
+const spliceLines = (content, lineNumber, deleteCount = 0, newLines = []) => {
+  const lines = content.split('\n');
+  lines.splice(lineNumber, deleteCount, ...newLines);
+  return lines.join('\n');
+};
+
+const mapLines = (content, mapFn) =>
+  content
+    .split('\n')
+    .map(mapFn)
+    .join('\n');
+
+describe('IDE lib/create_file_diff', () => {
+  it('returns empty string with "garbage" action', () => {
+    const result = createFileDiff(createNewFile(PATH, ''), 'garbage');
+
+    expect(result).toBe('');
+  });
+
+  it('preserves ending whitespace in file', () => {
+    const oldContent = spliceLines(TEXT, 99, 1, ['100 ']);
+    const newContent = spliceLines(oldContent, 99, 0, ['Lorem', 'Ipsum']);
+    const expected = `
+ 99
++Lorem
++Ipsum
+ 100 `;
+
+    const result = createFileDiff(
+      createUpdatedFile(PATH, oldContent, newContent),
+      commitActionTypes.update,
+    );
+
+    expect(result).toContain(expected);
+  });
+
+  describe('with "create" action', () => {
+    const expectedHead = `diff --git "a/${PATH}" "b/${PATH}"
+new file mode 100644`;
+
+    const expectedChunkHead = lineCount => `--- /dev/null
++++ b/${PATH}
+@@ -0,0 +1,${lineCount} @@`;
+
+    it('with empty file, does not include diff body', () => {
+      const result = createFileDiff(createNewFile(PATH, ''), commitActionTypes.create);
+
+      expect(result).toBe(`${expectedHead}\n`);
+    });
+
+    it('with single line, includes diff body', () => {
+      const result = createFileDiff(createNewFile(PATH, '\n'), commitActionTypes.create);
+
+      expect(result).toBe(`${expectedHead}
+${expectedChunkHead(1)}
++
+`);
+    });
+
+    it('without newline, includes no newline comment', () => {
+      const result = createFileDiff(createNewFile(PATH, 'Lorem ipsum'), commitActionTypes.create);
+
+      expect(result).toBe(`${expectedHead}
+${expectedChunkHead(1)}
++Lorem ipsum
+\\ No newline at end of file
+`);
+    });
+
+    it('with content, includes diff body', () => {
+      const content = `${TEXT}\n`;
+      const result = createFileDiff(createNewFile(PATH, content), commitActionTypes.create);
+
+      expect(result).toBe(`${expectedHead}
+${expectedChunkHead(TEXT_LINE_COUNT)}
+${mapLines(TEXT, line => `+${line}`)}
+`);
+    });
+  });
+
+  describe('with "delete" action', () => {
+    const expectedHead = `diff --git "a/${PATH}" "b/${PATH}"
+deleted file mode 100644`;
+
+    const expectedChunkHead = lineCount => `--- a/${PATH}
++++ /dev/null
+@@ -1,${lineCount} +0,0 @@`;
+
+    it('with empty file, does not include diff body', () => {
+      const result = createFileDiff(createDeletedFile(PATH, ''), commitActionTypes.delete);
+
+      expect(result).toBe(`${expectedHead}\n`);
+    });
+
+    it('with content, includes diff body', () => {
+      const content = `${TEXT}\n`;
+      const result = createFileDiff(createDeletedFile(PATH, content), commitActionTypes.delete);
+
+      expect(result).toBe(`${expectedHead}
+${expectedChunkHead(TEXT_LINE_COUNT)}
+${mapLines(TEXT, line => `-${line}`)}
+`);
+    });
+  });
+
+  describe('with "update" action', () => {
+    it('includes diff body', () => {
+      const oldContent = `${TEXT}\n`;
+      const newContent = `${spliceLines(TEXT, 50, 3, ['Lorem'])}\n`;
+
+      const result = createFileDiff(
+        createUpdatedFile(PATH, oldContent, newContent),
+        commitActionTypes.update,
+      );
+
+      expect(result).toBe(`diff --git "a/${PATH}" "b/${PATH}"
+--- a/${PATH}
++++ b/${PATH}
+@@ -47,11 +47,9 @@
+ 47
+ 48
+ 49
+ 50
+-51
+-52
+-53
++Lorem
+ 54
+ 55
+ 56
+ 57
+`);
+    });
+  });
+
+  describe('with "move" action', () => {
+    it('returns rename head', () => {
+      const result = createFileDiff(createMovedFile(PATH, PATH_FOO), commitActionTypes.move);
+
+      expect(result).toBe(`diff --git "a/${PATH_FOO}" "b/${PATH}"
+rename from ${PATH_FOO}
+rename to ${PATH}
+`);
+    });
+  });
+});