Add jest snapshot testing

.babelrc

@@ -17,5 +17,17 @@
       }
     ],
     "babel-preset-react"
-  ]
+  ],
+  "env": {
+    "test": {
+      "presets": [
+        [
+          "env",
+          {
+            "modules": "commonjs",
+          }
+        ]
+      ]
+    }
+  },
 }

jest.config.js

@@ -0,0 +1,16 @@
+module.exports = {
+  "globals": {
+    "gettext": (t) => { return t; },
+  },
+  "modulePaths": [
+    "common/static/common/js/components",
+  ],
+  "testMatch": [
+    "**/ProblemBrowser/**/*.test.jsx",
+    "common/static/common/js/components/**/?(*.)+(spec|test).js?(x)",
+  ],
+  "transform": {
+    "^.+\\.jsx$": "babel-jest",
+    "^.+\\.js$": "babel-jest",
+  },
+}

lms/djangoapps/instructor/static/instructor/ProblemBrowser/components/Main/Main.test.jsx

@@ -0,0 +1,9 @@
+import React from 'react';
+import Main from './Main.jsx';
+import renderer from 'react-test-renderer';
+
+test('My first demo test', () => {
+  const component = renderer.create(<Main></Main>);
+  let tree = component.toJSON();
+  expect(tree).toMatchSnapshot();
+});

lms/djangoapps/instructor/static/instructor/ProblemBrowser/components/Main/__snapshots__/Main.test.jsx.snap

@@ -0,0 +1,22 @@
+// Jest Snapshot v1, https://goo.gl/fbAQLP
+
+exports[`My first demo test 1`] = `
+<div
+  className="problem-browser"
+>
+  <button
+    className="btn"
+    onBlur={[Function]}
+    onClick={[Function]}
+    onKeyDown={[Function]}
+    type="button"
+  >
+    Select a section or problem
+  </button>
+  <input
+    disabled={true}
+    name="problem-location"
+    type="text"
+  />
+</div>
+`;