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/response.jsx

@@ -0,0 +1,60 @@
+import React from "react"
+import { shallow } from "enzyme"
+import { fromJS, List } from "immutable"
+import Response from "components/response"
+import ModelExample from "components/model-example"
+import { inferSchema } from "corePlugins/samples/fn"
+
+describe("<Response />", function () {
+  const dummyComponent = () => null
+  const components = {
+    headers: dummyComponent,
+    highlightCode: dummyComponent,
+    modelExample: ModelExample,
+    Markdown: dummyComponent,
+    operationLink: dummyComponent,
+    contentType: dummyComponent
+  }
+  const props = {
+    getComponent: c => components[c],
+    specSelectors: {
+      isOAS3() {
+        return false
+      }
+    },
+    fn: {
+      inferSchema
+    },
+    contentType: "application/json",
+    className: "for-test",
+    specPath: List(),
+    response: fromJS({
+      schema: {
+        type: "object",
+        properties: {
+          // Note reverse order: c, b, a
+          "c": {
+            type: "integer"
+          },
+          "b": {
+            type: "boolean"
+          },
+          "a": {
+            type: "string"
+          }
+        }
+      }
+    }),
+    code: "200"
+  }
+
+  it("renders the model-example schema properties in order", function () {
+    const wrapper = shallow(<Response {...props} />)
+    const renderedModelExample = wrapper.find(ModelExample)
+    expect(renderedModelExample.length).toEqual(1)
+
+    // Assert the schema's properties have maintained their order
+    const modelExampleSchemaProperties = renderedModelExample.props().schema.toJS().properties
+    expect(Object.keys(modelExampleSchemaProperties)).toEqual(["c", "b", "a"])
+  })
+})