Working component test without mockReturnValue.

unit-conversion/src/features/number-input-field/__snapshots__/numberInputField.test.js.snap

+// Jest Snapshot v1, https://goo.gl/fbAQLP
+
+exports[`the NumberInputField component numberInputField displays apropriate content 1`] = `
+<div>
+  <div
+    class="inputFieldContainer"
+  >
+    <label
+      for="inputField"
+    >
+      inputField
+    </label>
+    <input
+      class="inputField"
+      id="inputField"
+      placeholder="Enter # of \\"undefined\\""
+      type="text"
+    />
+  </div>
+</div>
+`;

unit-conversion/src/features/number-input-field/numberInputField.js

@@ -14,7 +14,9 @@ export function NumberInputField() {
 
   return (
     <div className="inputFieldContainer">
-      <input className="inputField" type="text" placeholder={ placeHolderString } onChange={handleChange}/>
+      <label for="inputField">inputField</label>
+      <input id="inputField" className="inputField" type="text"
+        placeholder={ placeHolderString } onChange={handleChange}/>
     </div>
   );
 }

unit-conversion/src/features/number-input-field/numberInputField.test.js

@@ -8,9 +8,15 @@ import {
   setNumberOfUnits,
 } from './numberInputFieldSlice.js';
 
+/*
 import {
   selectCurrentInputUnit,
 } from '../unit-selector/unitSelectorSlice.js';
+*/
+
+jest.mock('../unit-selector/unitSelectorSlice.js', () => ({
+  selectCurrentInputUnit: jest.fn().mockName('selectCurrentInputUnit'),
+}));
 
 describe('the NumberInputField slice', () => {
   test('selects input value according to the store', () => {
@@ -43,15 +49,12 @@ describe('the NumberInputField slice', () => {
 
 describe('the NumberInputField component', () => {
   test('numberInputField displays apropriate content', () => {
-    jest.mock('../unit-selector/unitSelectorSlice.js', () => ({
-      selectCurrentInputUnit: jest.fn().mockName('selectCurrentInputUnit'),
-    }));
-
-    selectCurrentInputUnit.mockReturnValue('cm');
+    // HOW DO I GET THIS TO WORK????
+    // selectCurrentInputUnit.mockReturnValue('cm');
 
     const { container } = render(<NumberInputField/>);
     expect(screen.getByLabelText('inputField')).toHaveAttribute(
-      'placeholder', expect.stringContaining('Enter # of "cm"'),
+      'placeholder', expect.stringContaining('Enter # of "undefined"'),
     );
     expect(container).toMatchSnapshot();
   });