From db90a53e38b269698646678c4a6c20ad2d69cbc7 Mon Sep 17 00:00:00 2001
From: Justin Albano <albanoj2@users.noreply.github.com>
Date: Tue, 30 Jul 2019 15:54:17 -0400
Subject: [PATCH] BAEL-3141: Added test cases for String to Double conversion.
 (#7448)

These tests exercise the conversion of Strings that can be converted to
Doubles, as well as the exceptions that are thrown for invalid Strings.
---
 .../StringToDoubleConversionUnitTest.java     | 56 +++++++++++++++++++
 1 file changed, 56 insertions(+)
 create mode 100644 java-strings-2/src/test/java/com/baeldung/string/todouble/StringToDoubleConversionUnitTest.java

diff --git a/java-strings-2/src/test/java/com/baeldung/string/todouble/StringToDoubleConversionUnitTest.java b/java-strings-2/src/test/java/com/baeldung/string/todouble/StringToDoubleConversionUnitTest.java
new file mode 100644
index 0000000000..9abb7ac453
--- /dev/null
+++ b/java-strings-2/src/test/java/com/baeldung/string/todouble/StringToDoubleConversionUnitTest.java
@@ -0,0 +1,56 @@
+package com.baeldung.string.todouble;
+
+import static org.junit.Assert.assertEquals;
+
+import java.text.DecimalFormat;
+import java.text.ParseException;
+
+import org.junit.Test;
+
+public class StringToDoubleConversionUnitTest {
+
+    @Test
+    public void givenValidString_WhenParseDouble_ThenResultIsPrimitiveDouble() {
+        assertEquals(1.23, Double.parseDouble("1.23"), 0.000001);
+    }
+    
+    @Test(expected = NullPointerException.class)
+    public void givenNullString_WhenParseDouble_ThenNullPointerExceptionIsThrown() {
+        Double.parseDouble(null);
+    }
+    
+    @Test(expected = NumberFormatException.class)
+    public void givenInalidString_WhenParseDouble_ThenNumberFormatExceptionIsThrown() {
+        Double.parseDouble("&");
+    }
+    
+    @Test
+    public void givenValidString_WhenValueOf_ThenResultIsPrimitiveDouble() {
+        assertEquals(1.23, Double.valueOf("1.23"), 0.000001);
+    }
+    
+    @Test(expected = NullPointerException.class)
+    public void givenNullString_WhenValueOf_ThenNullPointerExceptionIsThrown() {
+        Double.valueOf(null);
+    }
+    
+    @Test(expected = NumberFormatException.class)
+    public void givenInalidString_WhenValueOf_ThenNumberFormatExceptionIsThrown() {
+        Double.valueOf("&");
+    }
+    
+    @Test
+    public void givenValidString_WhenDecimalFormat_ThenResultIsValidDouble() throws ParseException {
+        assertEquals(1.23, new DecimalFormat("#").parse("1.23").doubleValue(), 0.000001);
+    }
+    
+    @Test(expected = NullPointerException.class)
+    public void givenNullString_WhenDecimalFormat_ThenNullPointerExceptionIsThrown() throws ParseException {
+        new DecimalFormat("#").parse(null);
+    }
+    
+    @Test(expected = ParseException.class)
+    public void givenInvalidString_WhenDecimalFormat_ThenParseExceptionIsThrown() throws ParseException {
+        new DecimalFormat("#").parse("&");
+    }
+}