Do not compare image if the same buffer (#126)

closes:  Visual-Regression-Tracker/Visual-Regression-Tracker#248

Author: pashidlos

src/test-runs/test-runs.service.spec.ts

@@ -315,6 +315,28 @@ describe('TestRunsService', () => {
       });
     });
 
+    it('diff not found', async () => {
+      const baseline = new PNG({
+        width: 20,
+        height: 20,
+      });
+      const image = new PNG({
+        width: 20,
+        height: 20,
+      });
+      service = await initService({});
+
+      const result = service.getDiff(baseline, image, baseTestRun);
+
+      expect(result).toStrictEqual({
+        status: TestStatus.ok,
+        diffName: null,
+        pixelMisMatchCount: 0,
+        diffPercent: 0,
+        isSameDimension: true,
+      });
+    });
+
     it('diff image dimensions mismatch', async () => {
       delete process.env.ALLOW_DIFF_DIMENSIONS;
       const baseline = new PNG({
@@ -341,35 +363,35 @@ describe('TestRunsService', () => {
     it('diff image dimensions mismatch ALLOWED', async () => {
       process.env.ALLOW_DIFF_DIMENSIONS = 'true';
       const baseline = new PNG({
-        width: 20,
-        height: 10,
+        width: 1,
+        height: 5,
       });
       const image = new PNG({
-        width: 10,
-        height: 20,
+        width: 2,
+        height: 4,
       });
       const diffName = 'diff name';
       const saveImageMock = jest.fn().mockReturnValueOnce(diffName);
-      mocked(Pixelmatch).mockReturnValueOnce(200);
+      mocked(Pixelmatch).mockReturnValueOnce(5);
       service = await initService({ saveImageMock });
 
       const result = service.getDiff(baseline, image, baseTestRun);
 
       expect(mocked(Pixelmatch)).toHaveBeenCalledWith(
         new PNG({
-          width: 20,
-          height: 20,
+          width: 2,
+          height: 5,
         }).data,
         new PNG({
-          width: 20,
-          height: 20,
+          width: 2,
+          height: 5,
         }).data,
         new PNG({
-          width: 20,
-          height: 20,
+          width: 2,
+          height: 5,
         }).data,
-        20,
-        20,
+        2,
+        5,
         {
           includeAA: true,
         }
@@ -378,35 +400,12 @@ describe('TestRunsService', () => {
       expect(result).toStrictEqual({
         status: TestStatus.unresolved,
         diffName,
-        pixelMisMatchCount: 200,
+        pixelMisMatchCount: 5,
         diffPercent: 50,
         isSameDimension: false,
       });
     });
 
-    it('diff not found', async () => {
-      const baseline = new PNG({
-        width: 10,
-        height: 10,
-      });
-      const image = new PNG({
-        width: 10,
-        height: 10,
-      });
-      service = await initService({});
-      mocked(Pixelmatch).mockReturnValueOnce(0);
-
-      const result = service.getDiff(baseline, image, baseTestRun);
-
-      expect(result).toStrictEqual({
-        status: TestStatus.ok,
-        diffName: null,
-        pixelMisMatchCount: 0,
-        diffPercent: 0,
-        isSameDimension: true,
-      });
-    });
-
     it('diff found < tollerance', async () => {
       const testRun: TestRun = {
         ...baseTestRun,
@@ -418,6 +417,7 @@ describe('TestRunsService', () => {
         width: 100,
         height: 100,
       });
+      baseline.data[0] = 1
       const image = new PNG({
         width: 100,
         height: 100,
@@ -450,6 +450,7 @@ describe('TestRunsService', () => {
         width: 100,
         height: 100,
       });
+      baseline.data[0] = 1
       const image = new PNG({
         width: 100,
         height: 100,

src/test-runs/test-runs.service.ts

@@ -270,11 +270,20 @@ export class TestRunsService {
 
     result.isSameDimension = baseline.width === image.width && baseline.height === image.height;
 
+    if (baseline.data.equals(image.data)) {
+      // equal images
+      result.status = TestStatus.ok;
+      result.pixelMisMatchCount = 0;
+      result.diffPercent = 0;
+      return result;
+    }
+
     if (!result.isSameDimension && !process.env.ALLOW_DIFF_DIMENSIONS) {
       // diff dimensions
       result.status = TestStatus.unresolved;
       return result;
     }
+
     // scale image to max size
     const maxWidth = Math.max(baseline.width, image.width);
     const maxHeight = Math.max(baseline.height, image.height);