correctly support --ci (#67)

* feat(diff-snapshot): correctly support continuous integration
americanexpress · Apr 17, 2018 · 967d6f8 · 967d6f8
1 parent 19ef5c5
commit 967d6f8
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Showing 3 changed files with 78 additions and 16 deletions.
diff --git a/__tests__/index.spec.js b/__tests__/index.spec.js
@@ -114,7 +114,7 @@ describe('toMatchImageSnapshot', () => {
       isNot: false,
       snapshotState: {
         _counters: new Map(),
-        _updateSnapshot: 'none',
+        _updateSnapshot: 'new',
         updated: undefined,
         added: true,
       },
@@ -144,7 +144,7 @@ describe('toMatchImageSnapshot', () => {
       isNot: false,
       snapshotState: {
         _counters: new Map(),
-        _updateSnapshot: 'none',
+        _updateSnapshot: 'new',
         updated: undefined,
         added: true,
       },
@@ -178,7 +178,7 @@ describe('toMatchImageSnapshot', () => {
       isNot: false,
       snapshotState: {
         _counters: new Map(),
-        _updateSnapshot: 'none',
+        _updateSnapshot: 'new',
         updated: undefined,
         added: true,
       },
@@ -233,16 +233,64 @@ describe('toMatchImageSnapshot', () => {
       snapshotState: {
         _counters: new Map(),
         update: false,
+        _updateSnapshot: 'new',
         updated: undefined,
         added: true,
       },
     };
-    const mockDiffResult = { added: true };
+    const mockDiff = jest.fn();
+    jest.doMock('../src/diff-snapshot', () => ({
+      diffImageToSnapshot: mockDiff,
+    }));
+
+    const mockFs = Object.assign({}, fs, {
+      existsSync: jest.fn(),
+      unlinkSync: jest.fn(),
+    });
+
+    mockFs.existsSync.mockReturnValueOnce(false);
+    mockDiff.mockReturnValueOnce({ added: true });
 
-    setupMock(mockDiffResult);
     const { toMatchImageSnapshot } = require('../src/index');
     const matcherAtTest = toMatchImageSnapshot.bind(mockTestContext);
-    expect(() => matcherAtTest('pretendthisisanimagebuffer')).not.toThrow();
+    expect(matcherAtTest('pretendthisisanimagebuffer')).toHaveProperty('pass', true);
+    expect(mockDiff).toHaveBeenCalled();
+  });
+
+  it('should fail when a new snapshot is added in ci', () => {
+    const mockTestContext = {
+      testPath: 'path/to/test.spec.js',
+      currentTestName: 'test1',
+      isNot: false,
+      snapshotState: {
+        _counters: new Map(),
+        update: false,
+        _updateSnapshot: 'none',
+        updated: undefined,
+        added: true,
+      },
+    };
+
+    const mockDiff = jest.fn();
+    jest.doMock('../src/diff-snapshot', () => ({
+      diffImageToSnapshot: mockDiff,
+    }));
+
+    const mockFs = Object.assign({}, fs, {
+      existsSync: jest.fn(),
+      unlinkSync: jest.fn(),
+    });
+
+    mockFs.existsSync.mockReturnValueOnce(false);
+
+
+    const { toMatchImageSnapshot } = require('../src/index');
+    const matcherAtTest = toMatchImageSnapshot.bind(mockTestContext);
+    const result = matcherAtTest('pretendthisisanimagebuffer');
+    expect(result).toHaveProperty('pass', false);
+    expect(result).toHaveProperty('message');
+    expect(result.message()).toContain('continuous integration');
+    expect(mockDiff).not.toHaveBeenCalled();
   });
 
   it('should work when a snapshot is updated', () => {

diff --git a/package.json b/package.json
@@ -8,7 +8,7 @@
   },
   "scripts": {
     "lint": "eslint ./ --ignore-path .gitignore --ext .js",
-    "test": "jest",
+    "test": "jest --ci=false",
     "posttest": "npm run lint"
   },
   "keywords": [

diff --git a/src/index.js b/src/index.js
@@ -17,6 +17,7 @@ const merge = require('lodash/merge');
 const path = require('path');
 const Chalk = require('chalk').constructor;
 const { diffImageToSnapshot } = require('./diff-snapshot');
+const fs = require('fs');
 
 const SNAPSHOTS_DIR = '__image_snapshots__';
 
@@ -47,15 +48,28 @@ function configureToMatchImageSnapshot({
     updateSnapshotState(snapshotState, { _counters: snapshotState._counters.set(currentTestName, (snapshotState._counters.get(currentTestName) || 0) + 1) }); // eslint-disable-line max-len
     const snapshotIdentifier = customSnapshotIdentifier || kebabCase(`${path.basename(testPath)}-${currentTestName}-${snapshotState._counters.get(currentTestName)}`);
 
-    const result = diffImageToSnapshot({
-      receivedImageBuffer: received,
-      snapshotIdentifier,
-      snapshotsDir: customSnapshotsDir || path.join(path.dirname(testPath), SNAPSHOTS_DIR),
-      updateSnapshot: snapshotState._updateSnapshot === 'all',
-      customDiffConfig: Object.assign({}, commonCustomDiffConfig, customDiffConfig),
-      failureThreshold,
-      failureThresholdType,
-    });
+    const snapshotsDir = customSnapshotsDir || path.join(path.dirname(testPath), SNAPSHOTS_DIR);
+    const baselineSnapshotPath = path.join(snapshotsDir, `${snapshotIdentifier}-snap.png`);
+
+    if (snapshotState._updateSnapshot === 'none' && !fs.existsSync(baselineSnapshotPath)) {
+      return {
+        pass: false,
+        message: () => `New snapshot was ${chalk.bold.red('not written')}. The update flag must be explicitly ` +
+        'passed to write a new snapshot.\n\n + This is likely because this test is run in a continuous ' +
+        'integration (CI) environment in which snapshots are not written by default.\n\n',
+      };
+    }
+
+    const result =
+      diffImageToSnapshot({
+        receivedImageBuffer: received,
+        snapshotsDir,
+        snapshotIdentifier,
+        updateSnapshot: snapshotState._updateSnapshot === 'all',
+        customDiffConfig: Object.assign({}, commonCustomDiffConfig, customDiffConfig),
+        failureThreshold,
+        failureThresholdType,
+      });
 
     let pass = true;
     /*