test: consolidate unit tests (#9588)

All mocha tests have been migrated to Jest tests.

Closes #9564

test/unit/components/highlight-code.jsx

@@ -0,0 +1,30 @@
+import React from "react"
+import expect from "expect"
+import { shallow, mount } from "enzyme"
+import HighlightCode from "core/components/highlight-code"
+
+const fakeGetConfigs = () => ({syntaxHighlight: {activated: true, theme: "agate"}})
+
+describe("<HighlightCode />", () => {
+  it("should render a Download button if downloadable", () => {
+    const props = {downloadable: true, getConfigs: fakeGetConfigs }
+    const wrapper = shallow(<HighlightCode {...props} />)
+    expect(wrapper.find(".download-contents").length).toEqual(1)
+  })
+
+  it("should render a Copy To Clipboard button if copyable", () => {
+    const props = {canCopy: true, getConfigs: fakeGetConfigs }
+    const wrapper = shallow(<HighlightCode {...props} />)
+    expect(wrapper.find("CopyToClipboard").length).toEqual(1)
+  })
+
+  it("should render values in a preformatted element", () => {
+    const value = "test text"
+    const props = {value: value, getConfigs: fakeGetConfigs}
+    const wrapper = mount(<HighlightCode {...props} />)
+    const preTag = wrapper.find("pre")
+
+    expect(preTag.length).toEqual(1)
+    expect(preTag.text()).toEqual(value)
+  })
+})