[WIP] Remove usage of retainLines

packages/jest-util/src/__tests__/get_callsite.test.js

@@ -0,0 +1,58 @@
+import fs from 'fs';
+import SourceMap from 'source-map';
+import getCallsite from '../get_callsite';
+
+jest.mock('fs');
+
+describe('getCallsite', () => {
+  beforeEach(() => {
+    fs.readFileSync = jest.fn();
+  });
+
+  test('without source map', () => {
+    const site = getCallsite(0);
+
+    expect(site.getFileName()).toEqual(__filename);
+    expect(site.getColumnNumber()).toEqual(expect.any(Number));
+    expect(site.getLineNumber()).toEqual(expect.any(Number));
+    expect(fs.readFileSync).not.toHaveBeenCalled();
+  });
+
+  test('ignores errors when fs throws', () => {
+    fs.readFileSync.mockImplementation(() => {
+      throw new Error('Mock error');
+    });
+
+    const site = getCallsite(0, {[__filename]: 'mockedSourceMapFile'});
+
+    expect(site.getFileName()).toEqual(__filename);
+    expect(site.getColumnNumber()).toEqual(expect.any(Number));
+    expect(site.getLineNumber()).toEqual(expect.any(Number));
+    expect(fs.readFileSync).toHaveBeenCalledWith('mockedSourceMapFile', 'utf8');
+  });
+
+  test('reads source map file to determine line and column', () => {
+    const sourceMapColumn = 1;
+    const sourceMapLine = 2;
+    SourceMap.SourceMapConsumer = class {
+      originalPositionFor(params) {
+        expect(params).toMatchObject({
+          column: expect.any(Number),
+          line: expect.any(Number),
+        });
+
+        return {
+          column: sourceMapColumn,
+          line: sourceMapLine,
+        };
+      }
+    };
+
+    const site = getCallsite(0, {[__filename]: 'mockedSourceMapFile'});
+
+    expect(site.getFileName()).toEqual(__filename);
+    expect(site.getColumnNumber()).toEqual(sourceMapColumn);
+    expect(site.getLineNumber()).toEqual(sourceMapLine);
+    expect(fs.readFileSync).toHaveBeenCalledWith('mockedSourceMapFile', 'utf8');
+  });
+});