refactor. 문자열 계산기 테스트 코드 JUnit -> AssertJ로 리팩토링

Author: dh2906

src/test/java/StringCalculatorTest.java

@@ -1,5 +1,4 @@
 import domain.StringCalculator;
-import org.junit.jupiter.api.Assertions;
 import org.junit.jupiter.api.Test;
 import org.junit.jupiter.params.ParameterizedTest;
 import org.junit.jupiter.params.provider.CsvSource;
@@ -8,30 +7,32 @@
 
 import java.util.List;
 
-import static org.junit.jupiter.api.Assertions.assertEquals;
-import static org.junit.jupiter.api.Assertions.assertThrows;
+import static org.assertj.core.api.Assertions.*;
 
 public class StringCalculatorTest {
     private final StringCalculator stringCalculator = new StringCalculator();
 
     @ParameterizedTest
-    @ValueSource(strings = {"1,2,3:4", "1 , 2: 3,4 "})
+    @ValueSource(strings = {
+            "1,2,3:4",
+            "1 , 2: 3,4 "
+    })
     public void 기본_구분자_문자열_계산기_테스트(String str) {
         int actual = stringCalculator.calculate(str);
 
-        assertEquals(10, actual);
+        assertThat(actual).isEqualTo(10);
     }
 
     @ParameterizedTest
     @CsvSource({
-            " '//+\n', '+' ",
-            " '// \n', ' ' ",
-            " '//||\n', '||' "
+            "'//+\n', '+'",
+            "'// \n', ' '",
+            "'//||\n', '||'"
     })
     public void 커스텀_구분자_파싱_테스트(String str, String expected) {
         String customDelimeter = stringCalculator.findCustomDelimeter(str);
 
-        assertEquals(expected, customDelimeter);
+        assertThat(customDelimeter).isEqualTo(expected);
     }
 
     @Test
@@ -40,21 +41,25 @@ public class StringCalculatorTest {
 
         List<Integer> actual = stringCalculator.parseNumber(tokens);
 
-        assertEquals(List.of(1, 2, 3, 4), actual);
+        assertThat(actual).containsExactly(1, 2, 3, 4);
     }
 
     @Test
     public void 문자열_리스트_정수_리스트로_변환_음수가_포함되면_예외_발생() {
         String[] tokens = {"1", "2", "-3", "4"};
 
-        assertThrows(RuntimeException.class, () -> stringCalculator.parseNumber(tokens));
+        assertThatThrownBy(() -> stringCalculator.parseNumber(tokens))
+                .isInstanceOf(RuntimeException.class)
+                .hasMessageContaining("음수는 처리할 수 없습니다.");
     }
 
     @Test
     public void 문자열_리스트_정수_리스트로_변환_문자가_포함되면_예외_발생() {
         String[] tokens = {"a1", "b", " ", "4"};
 
-        assertThrows(RuntimeException.class, () -> stringCalculator.parseNumber(tokens));
+        assertThatThrownBy(() -> stringCalculator.parseNumber(tokens))
+                .isInstanceOf(RuntimeException.class)
+                .hasMessageContaining("문자열은 처리할 수 없습니다.");
     }
 
     @ParameterizedTest
@@ -66,7 +71,7 @@ public class StringCalculatorTest {
     public void 커스텀_구분자_문자열_계산기_테스트(String str) {
         int actual = stringCalculator.calculate(str);
 
-        assertEquals(10, actual);
+        assertThat(actual).isEqualTo(10);
     }
 
     @ParameterizedTest
@@ -76,7 +81,9 @@ public class StringCalculatorTest {
             "//\n1;2;3;4"
     })
     public void 커스텀_구분자_형식에_맞지_않은_경우_예외_발생(String str) {
-        assertThrows(RuntimeException.class, () -> stringCalculator.calculate(str));
+        assertThatThrownBy(() -> stringCalculator.calculate(str))
+                .isInstanceOf(RuntimeException.class)
+                .hasMessageContaining("커스텀 구분자를 찾을 수 없습니다.");
     }
 
     @ParameterizedTest
@@ -86,14 +93,16 @@ public class StringCalculatorTest {
             " "
     })
     public void 문자열이_비어있는_경우_예외_발생(String str) {
-        assertThrows(RuntimeException.class, () -> stringCalculator.calculate(str));
+        assertThatThrownBy(() -> stringCalculator.calculate(str))
+                .isInstanceOf(RuntimeException.class)
+                .hasMessageContaining("문자열이 비어있습니다.");
     }
 
     @Test
     public void 구분자_없이_숫자만_입력한_경우() {
         String str = "1";
         int actual = stringCalculator.calculate(str);
 
-        assertEquals(1, actual);
+        assertThat(actual).isEqualTo(1);
     }
 }