MM-T2369 : Aspect Ratio is preserved in RHS (#8165)

* test

* Update e2e/cypress/integration/scroll/image_aspect_ratio_spec.js

Co-authored-by: Saturnino Abril <saturnino.abril@gmail.com>

e2e/cypress/integration/scroll/image_aspect_ratio_spec.js

@@ -0,0 +1,71 @@
+// Copyright (c) 2015-present Mattermost, Inc. All Rights Reserved.
+// See LICENSE.txt for license information.
+
+// ***************************************************************
+// - [#] indicates a test step (e.g. # Go to a page)
+// - [*] indicates an assertion (e.g. * Check the title)
+// - Use element ID when selecting an element. Create one if none.
+// ***************************************************************
+
+describe('Scroll', () => {
+    let testTeam;
+
+    beforeEach(() => {
+        // # Create new team and new user and visit Town Square channel
+        cy.apiInitSetup().then(({team, channel}) => {
+            testTeam = team;
+
+            cy.visit(`/${testTeam.name}/channels/${channel.name}`);
+        });
+    });
+
+    it('MM-T2369 Aspect Ratio is preserved in RHS', () => {
+        const uploadedImages = [
+            {
+                alt: 'Wide image',
+                width: 960,
+                height: 246,
+                src:
+                    'https://cdn.pixabay.com/photo/2017/10/10/22/24/wide-format-2839089_960_720.jpg',
+            },
+            {
+                alt: 'Tall image',
+                width: 400,
+                height: 950,
+                src:
+                    'https://media.npr.org/programs/atc/features/2009/may/short/abetall3-0483922b5fb40887fc9fbe20a606e256cbbd10ee-s800-c85.jpg',
+            },
+        ];
+
+        uploadedImages.forEach((uploadedImage) => {
+            // # Post the image as markdown image in the center
+            cy.uiPostMessageQuickly(`![${uploadedImage.alt}](${uploadedImage.src})`);
+
+            // # Get uploaded image in the center
+            cy.getLastPost().within(() => {
+                // * Verify image was uploaded and its aspect ratio is unchanged
+                verifyImageAspectRatioCorrectness(uploadedImage);
+            });
+
+            // # Open the message with image in RHS
+            cy.clickPostCommentIcon();
+
+            // # Go to RHS where image is now opened
+            cy.get('#rhsContainer').within(() => {
+                // * Verify image in the RHS has correct aspect ratio
+                verifyImageAspectRatioCorrectness(uploadedImage);
+            });
+        });
+    });
+});
+
+function verifyImageAspectRatioCorrectness(originalImage) {
+    cy.findByAltText(originalImage.alt).
+        should('exist').
+        and((img) => {
+            expect(img.width() / img.height()).to.be.closeTo(
+                originalImage.width / originalImage.height,
+                0.01,
+            );
+        });
+}