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/components/info-wrapper.jsx

@@ -0,0 +1,67 @@
+import React from "react"
+import { mount } from "enzyme"
+import { fromJS } from "immutable"
+import InfoContainer from "containers/info"
+
+describe("<InfoContainer/>", function () {
+
+  const components = {
+    info: () => <span className="mocked-info"/>
+  }
+  const mockedProps = {
+    specSelectors: {
+      info () {},
+      url () {},
+      basePath () {},
+      host () {},
+      externalDocs () {},
+    },
+    oas3Selectors: {
+      selectedServer () {},
+    },
+    getComponent: c => components[c]
+  }
+
+  it("renders Info inside InfoContainer if info is provided", function () {
+
+    // Given
+    let props = {...mockedProps}
+    props.specSelectors = {...mockedProps.specSelectors}
+    props.specSelectors.info = function () {return fromJS(["info1", "info2"])}
+
+    // When
+    let wrapper = mount(<InfoContainer {...props}/>)
+
+    // Then
+    const renderedInfo = wrapper.find("span.mocked-info")
+    expect(renderedInfo.length).toEqual(1)
+  })
+
+  it("does not render Info inside InfoContainer if no info is provided", function () {
+
+    // Given
+    let props = {...mockedProps}
+    props.specSelectors = {...mockedProps.specSelectors}
+    props.specSelectors.info = function () {return fromJS([])}
+
+    // When
+    let wrapper = mount(<InfoContainer {...props}/>)
+
+    // Then
+    const renderedInfo = wrapper.find("span.mocked-info")
+    expect(renderedInfo.length).toEqual(0)
+  })
+
+  it("does not render Info inside InfoContainer if info is undefined", function () {
+
+    // Given
+    let props = {...mockedProps}
+
+    // When
+    let wrapper = mount(<InfoContainer {...props}/>)
+
+    // Then
+    const renderedInfo = wrapper.find("span.mocked-info")
+    expect(renderedInfo.length).toEqual(0)
+  })
+})