react tutorial: fix behaviour of 0 and .

evesinger · Jan 23, 2020 · 2ff9cfa · 2ff9cfa
1 parent 106aa43
commit 2ff9cfa
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Showing 2 changed files with 8 additions and 3 deletions.
diff --git a/src/components/Calculator/Calculator.jsx b/src/components/Calculator/Calculator.jsx
@@ -87,9 +87,9 @@ class Calculator extends Component {
             // set displayValue to '0' if displayValue is empty string
             if (displayValue === '') displayValue = '0';
         } else {
-            // replace displayValue with value if displayValue equal to '0'
+            // replace displayValue with value if displayValue equal to '0' and it does not include the dot
             // else concatenate displayValue and value
-            displayValue === '0' ? displayValue = value : displayValue += value;
+            displayValue === '0' && value!== '.' ? displayValue = value : displayValue += value;
         }
 
         this.setState({ displayValue });

diff --git a/src/components/Calculator/Calculator.spec.js b/src/components/Calculator/Calculator.spec.js
@@ -88,6 +88,12 @@ describe('updateDisplay', () => {
         expect(wrapper.state('displayValue')).toEqual('0');
     });
 
+    it('prevents showing only . when 0 as initial value', () => {
+        wrapper.instance().updateDisplay('0');
+        wrapper.instance().updateDisplay('.');
+        expect(wrapper.state('displayValue')).toEqual('0.5');
+    });
+
     it('removes last char of displayValue', () => {
         wrapper.instance().updateDisplay('5');
         wrapper.instance().updateDisplay('0');
@@ -161,7 +167,6 @@ describe('callOperator', () => {
         expect(wrapper.state('displayValue')).toEqual('6.05');
     });
 
-
     it('updates displayValue to the sum of storedValue and displayValue', () => {
         wrapper.setState({ storedValue: '3' });
         wrapper.setState({ displayValue: '2' });