feat: migrate unit tests to Jest (#6353)

* config(jest): updated setup
* config(jest): update testMatch to include jsx files
* config(jest): add transformIgnorePatterns
* config(jest): update ignore files that do not work in jest yet
* config: add test:unit-jest to test script

* fix(jest): lint with eslint-plugin-jest

* refactor(jest): move unit test directory
* refactor(mocha): restore mocha tests that fail in jest

* docs(jest): update helpful scripts with test:unit-jest

test/unit/xss/markdown-script-sanitization.jsx

@@ -0,0 +1,34 @@
+import React from "react"
+import { render } from "enzyme"
+import Markdown from "components/providers/markdown"
+import { Markdown as OAS3Markdown } from "corePlugins/oas3/wrap-components/markdown.jsx"
+
+describe("Markdown Script Sanitization", function() {
+  describe("Swagger 2.0", function() {
+    it("sanitizes <script> elements", function() {
+      const str = `script <script>alert(1)</script>`
+      const el = render(<Markdown source={str} />)
+      expect(el.html()).toEqual(`<div class="markdown"><p>script </p>\n</div>`)
+    })
+
+    it("sanitizes <img> elements", function() {
+      const str = `<img src=x onerror="alert('img-in-description')">`
+      const el = render(<Markdown source={str} />)
+      expect(el.html()).toEqual(`<div class="markdown"><p><img src="x"></p>\n</div>`)
+    })
+  })
+
+  describe("OAS 3", function() {
+    it("sanitizes <script> elements", function() {
+      const str = `script <script>alert(1)</script>`
+      const el = render(<OAS3Markdown source={str} />)
+      expect(el.html()).toEqual(`<div class="renderedMarkdown"><p>script </p></div>`)
+    })
+
+    it("sanitizes <img> elements", function() {
+      const str = `<img src=x onerror="alert('img-in-description')">`
+      const el = render(<OAS3Markdown source={str} />)
+      expect(el.html()).toEqual(`<div class="renderedMarkdown"><p><img src="x"></p></div>`)
+    })
+  })
+})