(nobug) - Increase DSImage to 100% coverage (#5061)

test/unit/content-src/components/DiscoveryStreamComponents/DSImage.test.jsx

@@ -3,6 +3,11 @@ import {mount} from "enzyme";
 import React from "react";
 
 describe("Discovery Stream <DSImage>", () => {
+  let sandbox;
+  beforeEach(() => {
+    sandbox = sinon.createSandbox();
+  });
+
   it("should have a child with class ds-image", () => {
     const img = mount(<DSImage />);
     const child = img.find(".ds-image");
@@ -33,4 +38,47 @@ describe("Discovery Stream <DSImage>", () => {
     assert.equal(img.find("img").prop("src"), "https://img-getpocket.cdn.mozilla.net/640x480/filters:format(jpeg):quality(60):no_upscale():strip_exif()/https%3A%2F%2Fplacekitten.com%2Fg%2F640%2F480");
     assert.equal(img.find("img").prop("srcSet"), "https://img-getpocket.cdn.mozilla.net/1280x960/filters:format(jpeg):quality(60):no_upscale():strip_exif()/https%3A%2F%2Fplacekitten.com%2Fg%2F640%2F480 2x");
   });
+
+  it("should fall back to unoptimized when optimized failed", () => {
+    const img = mount(<DSImage source="https://placekitten.com/g/640/480" rawSource="https://placekitten.com/g/640/480" />);
+    img.setState({
+      isSeen: true,
+      containerWidth: 640,
+      containerHeight: 480,
+    });
+
+    img.instance().onOptimizedImageError();
+    img.update();
+
+    assert.equal(img.find("img").prop("src"), "https://placekitten.com/g/640/480");
+  });
+
+  it("should render a placeholder broken image when image failed", () => {
+    const img = mount(<DSImage />);
+    img.setState({isSeen: true});
+
+    img.instance().onNonOptimizedImageError();
+    img.update();
+
+    assert.equal(img.find("div").prop("className"), "broken-image");
+  });
+
+  it("should update state when seen", () => {
+    const img = mount(<DSImage rawSource="https://placekitten.com/g/640/480" />);
+
+    img.instance().onSeen([{isIntersecting: true}]);
+
+    assert.property(img.state(), "containerWidth");
+    assert.propertyVal(img.state(), "isSeen", true);
+  });
+
+  it("should stop observing when removed", () => {
+    const img = mount(<DSImage />);
+    const {observer} = img.instance();
+    sandbox.stub(observer, "unobserve");
+
+    img.unmount();
+
+    assert.calledOnce(observer.unobserve);
+  });
 });