Fixes inserting empty return if there is nothing in field (#464)

src/components/Input/Input.js

@@ -20,6 +20,7 @@ import Keys from '../../constants/Keys'
 import { classNames } from '../../utilities/classNames'
 import { namespaceComponent } from '../../utilities/component'
 import { createUniqueIDFactory } from '../../utilities/id'
+import { isModifierKeyPressed } from '../../utilities/keys'
 import { isDefined } from '../../utilities/is'
 import { noop, requestAnimationFrame } from '../../utilities/other'
 import {
@@ -353,15 +354,27 @@ export class Input extends Component<Props, State> {
   }
 
   insertCarriageReturnAtCursorIndex(event) {
-    if (!(event.ctrlKey || event.metaKey || event.altKey)) return
+    const cursorIndex = event.currentTarget.selectionStart
+    const nextValue = event.currentTarget.value
+    const prevValue = this.state.value
+
+    // this prevents a return being inserted if the field is completely empty
+    // this works on every modifier key, and with standalone returns
+    const isEmptyField =
+      cursorIndex == 0 && nextValue.length === 0 && prevValue.length === 0
+
+    if (isEmptyField) {
+      event.preventDefault() // prevents shift and return from inserting a line break
+      return
+    }
+
+    if (!isModifierKeyPressed(event)) return
+    // this inserts a return into the value if a modifier key is also pressed
     event.preventDefault()
     event.stopPropagation()
-    const cursorIndex = event.currentTarget.selectionStart
-    const currentValue = event.currentTarget.value
-    const newValue = `${currentValue.substr(
-      0,
+    const newValue = `${nextValue.substr(0, cursorIndex)}\n${nextValue.substr(
       cursorIndex
-    )}\n${currentValue.substr(cursorIndex)}`
+    )}`
     this.setState({ value: newValue }, () => {
       this.props.onChange(this.state.value)
       this.inputNode.setSelectionRange(cursorIndex + 1, cursorIndex + 1)

src/components/Input/__tests__/Input.test.js

@@ -185,18 +185,44 @@ describe('Events', () => {
 })
 
 describe('insertCarriageReturnsAtCursorIndex', () => {
-  test('expect state to get set', () => {
-    const onChangeSpy = jest.fn()
-    const setSelectionRangeSpy = jest.fn()
-    const preventDefaultSpy = jest.fn()
-    const stopPropagationSpy = jest.fn()
-    const wrapper = shallow(
+  let onChangeSpy,
+    preventDefaultSpy,
+    setSelectionRangeSpy,
+    stopPropagationSpy,
+    wrapper
+
+  beforeEach(() => {
+    onChangeSpy = jest.fn()
+    setSelectionRangeSpy = jest.fn()
+    preventDefaultSpy = jest.fn()
+    stopPropagationSpy = jest.fn()
+    wrapper = shallow(
       <Input hasInsertCarriageReturns={true} onChange={onChangeSpy} />
     )
     wrapper
       .instance()
       .setInputNodeRef({ setSelectionRange: setSelectionRangeSpy })
     wrapper.instance().setState = jest.fn((newState, callback) => callback())
+  })
+
+  test('if empty value with cursorIndex at 0, should only call preventDefault', () => {
+    wrapper.instance().insertCarriageReturnAtCursorIndex({
+      shiftKey: true,
+      preventDefault: preventDefaultSpy,
+      stopPropagation: stopPropagationSpy,
+      currentTarget: {
+        selectionStart: 0,
+        value: '',
+      },
+    })
+    expect(preventDefaultSpy).toHaveBeenCalledTimes(1)
+    expect(stopPropagationSpy).toHaveBeenCalledTimes(0)
+    expect(wrapper.instance().setState).toHaveBeenCalledTimes(0)
+    expect(onChangeSpy).toHaveBeenCalledTimes(0)
+    expect(setSelectionRangeSpy).toHaveBeenCalledTimes(0)
+  })
+
+  test('expect state to get set and update the value', () => {
     wrapper.instance().insertCarriageReturnAtCursorIndex({
       ctrlKey: true,
       preventDefault: preventDefaultSpy,