[LBP] 박세은 3, 4단계 과제 제출합니다.

build.gradle

@@ -11,7 +11,9 @@ repositories {
 
 dependencies {
     testImplementation platform('org.junit:junit-bom:5.9.1')
+    testImplementation platform('org.assertj:assertj-bom:3.25.1')
     testImplementation('org.junit.jupiter:junit-jupiter')
+    testImplementation('org.assertj:assertj-core')
 }
 
 test {

src/main/java/Calculator.java

@@ -13,8 +13,8 @@ public int multiply(int num1, int num2) {
     }
 
     public int divide(int dividend, int divisor) {
-        if(divisor == 0){
-            throw new ArithmeticException("0으로 나눌 수 없습니다.");
+        if (divisor == 0) {
+            throw new ArithmeticException("Divide by zero");
         }
         return dividend / divisor;
     }

src/main/java/StringCalculator.java

@@ -0,0 +1,81 @@
+import java.util.Arrays;
+
+public class StringCalculator {
+
+    private static int[] ExpressionToTokens(String expression) {
+        try {
+            String tokens = expression;
+            String delimiters = "[,:]";
+
+            if (expression.contains("//") && expression.contains("\n")) {
+                String customDelimiter = extractCustomDelimiter(expression);
+                tokens = extractToken(expression);
+                delimiters = "[,:" + customDelimiter + "]";
+            }
+
+            String[] splitTokens = tokens.split(delimiters);
+            return StringArrayToIntArray(splitTokens);
+        } catch (NumberFormatException e) {
+            throw new RuntimeException("Contains non-numerical values.");
+        }
+    }
+
+    private static String extractCustomDelimiter(String expression) {
+        int startIndex = expression.indexOf("//") + 2;
+        int endIndex = expression.indexOf("\n");
+        return expression.substring(startIndex, endIndex);
+    }
+
+    private static String extractToken(String expression) {
+        int startIndex = expression.indexOf("//");
+        int endIndex = expression.indexOf("\n");
+
+        return expression.substring(0, startIndex) + expression.substring(startIndex + 2, endIndex) + expression.substring(endIndex + 1);
+    }
+
+    private static int[] StringArrayToIntArray(String[] expression) {
+        return Arrays.stream(expression).mapToInt(Integer::parseInt).toArray();
+    }
+
+    public int add(String expression) {
+        int[] tokens = ExpressionToTokens(expression);
+        int answer = tokens[0];
+        for (int i = 1; i < tokens.length; i++) {
+            answer += tokens[i];
+        }
+        return answer;
+    }
+
+    public int subtract(String expression) {
+        int[] tokens = ExpressionToTokens(expression);
+        int answer = tokens[0];
+        for (int i = 1; i < tokens.length; i++) {
+            answer -= tokens[i];
+        }
+        return answer;
+    }
+
+    public int multiply(String expression) {
+        int[] tokens = ExpressionToTokens(expression);
+        int answer = tokens[0];
+        for (int i = 1; i < tokens.length; i++) {
+            answer *= tokens[i];
+        }
+        return answer;
+
+    }
+
+    public int divide(String expression) {
+        int[] tokens = ExpressionToTokens(expression);
+        int answer = tokens[0];
+        for (int i = 1; i < tokens.length; i++) {
+            if (tokens[i] == 0) {
+                throw new ArithmeticException("Divide by zero");
+            }
+            answer /= tokens[i];
+        }
+        return answer;
+
+    }
+}
+

src/test/java/CalculatorTest.java

@@ -1,7 +1,9 @@
 import org.junit.jupiter.api.DisplayName;
-import org.junit.jupiter.api.Test;
 import org.junit.jupiter.api.Nested;
-import static org.junit.jupiter.api.Assertions.*;
+import org.junit.jupiter.api.Test;
+
+import static org.assertj.core.api.Assertions.assertThat;
+import static org.assertj.core.api.Assertions.assertThatThrownBy;
 
 public class CalculatorTest {
 
@@ -11,14 +13,26 @@ public class CalculatorTest {
     @DisplayName("덧셈 테스트")
     class addTest {
 
+        private final Calculator calculator = new Calculator();
+
         @Test
-        @DisplayName("정수의 합")
-        void add_Test() {
+        @DisplayName("두 정수의 합을 반환한다.")
+        void shouldReturnSumOfTwoIntegers() {
             final int a = 3;
             final int b = 5;
-            final int actual = a+b;
+            final int actual = 8;
+
+            assertThat(actual).isEqualTo(calculator.add(a, b));
+        }
+
+        @Test
+        @DisplayName("두 음수 정수의 합을 반환한다.")
+        void shouldReturnSumOfTwoNegativeIntegers() {
+            final int a = -3;
+            final int b = -5;
+            final int actual = -8;
 
-            assertEquals(actual, calculator.add(a,b));
+            assertThat(actual).isEqualTo(calculator.add(a, b));
         }
     }
 
@@ -27,13 +41,23 @@ void add_Test() {
     class subtractTest {
 
         @Test
-        @DisplayName("정수의 차")
-        void subtract_Test() {
+        @DisplayName("두 정수의 차를 반환한다.")
+        void shouldReturnSubtractOfTwoIntegers() {
             final int a = 5;
             final int b = 3;
-            final int actual = a-b;
+            final int actual = a - b;
+
+            assertThat(actual).isEqualTo(calculator.subtract(a, b));
+        }
 
-            assertEquals(actual, calculator.subtract(a,b));
+        @Test
+        @DisplayName("두 음수 정수의 차를 반환한다.")
+        void shouldReturnSubtractOfTwoNegativeIntegers() {
+            final int a = -5;
+            final int b = -3;
+            final int actual = a - b;
+
+            assertThat(actual).isEqualTo(calculator.subtract(a, b));
         }
     }
 
@@ -42,13 +66,23 @@ void subtract_Test() {
     class multiplyTest {
 
         @Test
-        @DisplayName("정수의 곱셈")
-        void multiply_Test() {
+        @DisplayName("두 정수의 곱을 반환한다.")
+        void shouldReturnMultiplyOfTwoIntegers() {
             final int a = 5;
             final int b = 3;
-            final int actual = a*b;
+            final int actual = a * b;
+
+            assertThat(actual).isEqualTo(calculator.multiply(a, b));
+        }
+
+        @Test
+        @DisplayName("두 음수 정수의 곱을 반환한다.")
+        void shouldReturnMultiplyOfTwoNegativeIntegers() {
+            final int a = -5;
+            final int b = -3;
+            final int actual = a * b;
 
-            assertEquals(actual, calculator.multiply(a,b));
+            assertThat(actual).isEqualTo(calculator.multiply(a, b));
         }
     }
 
@@ -57,22 +91,32 @@ void multiply_Test() {
     class divideTest {
 
         @Test
-        @DisplayName("정수의 나눗셈")
-        void divide_Test() {
+        @DisplayName("두 정수의 몫을 반환한다.")
+        void shouldReturnDivideOfTwoIntegers() {
             final int a = 15;
             final int b = 3;
-            final int actual = a/b;
+            final int actual = a / b;
+
+            assertThat(actual).isEqualTo(calculator.divide(a, b));
+        }
+
+        @Test
+        @DisplayName("두 음수 정수의 몫을 반환한다.")
+        void shouldReturnDivideOfTwoNegativeIntegers() {
+            final int a = -15;
+            final int b = -3;
+            final int actual = a / b;
 
-            assertEquals(actual, calculator.divide(a,b));
+            assertThat(actual).isEqualTo(calculator.divide(a, b));
         }
 
         @Test
-        @DisplayName("0으로 나누었을 때 ArithmeticException 예외 발생")
-        void divideWithZero_Test() {
+        @DisplayName("정수를 0으로 나누면 ArithmeticException이 발생한다.")
+        void shouldReturnDivideWithZeroOfTwoIntegers() {
             final int a = 15;
             final int b = 0;
 
-            assertThrows(ArithmeticException.class, () -> calculator.divide(a,b));
+            assertThatThrownBy(() -> calculator.divide(a, b)).isInstanceOf(ArithmeticException.class);
         }
     }
 }