From 14f2ea2b701cef3ce4094b03d7a7f4b872774278 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?=EB=B0=95=ED=83=9C=EC=A7=84?=
 <140797244+taejinn@users.noreply.github.com>
Date: Thu, 31 Jul 2025 18:52:24 +0900
Subject: [PATCH 01/13] =?UTF-8?q?feat:=20=EA=B3=84=EC=82=B0=20=EA=B8=B0?=
 =?UTF-8?q?=EB=8A=A5=20=EC=B6=94=EA=B0=80?=
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

---
 src/main/java/Calc.java | 24 ++++++++++++++++++++++++
 1 file changed, 24 insertions(+)
 create mode 100644 src/main/java/Calc.java

diff --git a/src/main/java/Calc.java b/src/main/java/Calc.java
new file mode 100644
index 00000000..83fc66d4
--- /dev/null
+++ b/src/main/java/Calc.java
@@ -0,0 +1,24 @@
+public class Calc {
+    public int add(int a, int b) {
+        int res = a + b;
+        return res;
+    }
+
+    public int minus(int a, int b) {
+        int res = a - b;
+        return res;
+    }
+
+    public int times(int a, int b) {
+        int res = a * b;
+        return res;
+    }
+
+    public int divide(int a, int b) {
+        if (a == 0 || b == 0) {
+            throw new IllegalArgumentException("0 으로 나눌 수 없습니다.");
+        }
+        int res = a / b;
+        return res;
+    }
+}
\ No newline at end of file

From b47ba7f042352866b7ad9ffeca4d0fe0ebd29662 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?=EB=B0=95=ED=83=9C=EC=A7=84?=
 <140797244+taejinn@users.noreply.github.com>
Date: Thu, 31 Jul 2025 19:07:23 +0900
Subject: [PATCH 02/13] =?UTF-8?q?test:=20=EA=B3=84=EC=82=B0=20=EA=B8=B0?=
 =?UTF-8?q?=EB=8A=A5=20=ED=85=8C=EC=8A=A4=ED=8A=B8=20=EC=B6=94=EA=B0=80?=
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

---
 src/test/java/CalcTest.java | 47 +++++++++++++++++++++++++++++++++++++
 1 file changed, 47 insertions(+)
 create mode 100644 src/test/java/CalcTest.java

diff --git a/src/test/java/CalcTest.java b/src/test/java/CalcTest.java
new file mode 100644
index 00000000..bb948f6a
--- /dev/null
+++ b/src/test/java/CalcTest.java
@@ -0,0 +1,47 @@
+
+@DisplayName("계산기 작동 테스트")
+public class CalcTest {
+    @Test
+    @DisplayName("더하기 테스트")
+    void add() {
+        final var a = 1;
+        final var b = 2;
+        final var actual = a + b;
+        final var expected = 3;
+        
+        assertEquals(expected, actual);
+    }
+
+    @Test
+    @DisplayName("빼기 테스트")
+    void add() {
+        final var a = 3;
+        final var b = 1;
+        final var actual = a - b;
+        final var expected = 2;
+        
+        assertEquals(expected, actual);
+    }
+
+    @Test
+    @DisplayName("곱하기 테스트")
+    void add() {
+        final var a = 2;
+        final var b = 3;
+        final var actual = a * b;
+        final var expected = 6;
+        
+        assertEquals(expected, actual);
+    }
+
+    @Test
+    @DisplayName("나누기 테스트")
+    void add() {
+        final var a = 10;
+        final var b = 5;
+        final var actual = a / b;
+        final var expected = 2;
+        
+        assertEquals(expected, actual);
+    }
+}
\ No newline at end of file

From af86066af518d49b9270e21e0dd06315447be2c7 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?=EB=B0=95=ED=83=9C=EC=A7=84?=
 <140797244+taejinn@users.noreply.github.com>
Date: Thu, 31 Jul 2025 19:29:23 +0900
Subject: [PATCH 03/13] =?UTF-8?q?feat:=20=EB=AC=B8=EC=9E=90=EC=97=B4=20?=
 =?UTF-8?q?=EA=B3=84=EC=82=B0=EA=B8=B0=20=EC=B6=94=EA=B0=80?=
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

---
 src/main/java/StringCalc.java | 46 +++++++++++++++++++++++++++++++++++
 1 file changed, 46 insertions(+)
 create mode 100644 src/main/java/StringCalc.java

diff --git a/src/main/java/StringCalc.java b/src/main/java/StringCalc.java
new file mode 100644
index 00000000..5a698229
--- /dev/null
+++ b/src/main/java/StringCalc.java
@@ -0,0 +1,46 @@
+import java.util.regex.Matcher;
+import java.util.regex.Pattern;
+
+public class StringCalc {
+
+    private static final String defaultDelimiters = "[,:]";
+
+    public int add(String text) {
+        if (text == null || text.isEmpty()) {
+            return 0;
+        }
+
+        String delimiters = defaultDelimiters;
+        String actualTextToParse = text;
+
+        Pattern customDelimiterPattern = Pattern.compile("//(.)\n(.*)");
+        Matcher matcher = customDelimiterPattern.matcher(text);
+
+        if (matcher.find()) {
+            String customDelimiter = Pattern.quote(matcher.group(1));
+            delimiters = customDelimiter;
+            actualTextToParse = matcher.group(2);
+        }
+
+        String[] numbersAsString = actualTextToParse.split(delimiters);
+        int sum = 0;
+
+        for (String numStr : numbersAsString) {
+            if (numStr.isEmpty()) {
+                continue;
+            }
+
+            try {
+                int number = Integer.parseInt(numStr);
+
+                if (number < 0) {
+                    throw new RuntimeException("음수는 입력할 수 없습니다.");
+                }
+                sum += number;
+            } catch (NumberFormatException e) {
+                throw new RuntimeException("숫자 이외의 값이 포함되어 있습니다.");
+            }
+        }
+        return sum;
+    }
+}
\ No newline at end of file

From e872080f8902879df66a6819726a55a558bebc9c Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?=EB=B0=95=ED=83=9C=EC=A7=84?=
 <140797244+taejinn@users.noreply.github.com>
Date: Thu, 31 Jul 2025 19:36:07 +0900
Subject: [PATCH 04/13] =?UTF-8?q?test:=20=EA=B3=84=EC=82=B0=20=EA=B8=B0?=
 =?UTF-8?q?=EB=8A=A5=20=ED=85=8C=EC=8A=A4=ED=8A=B8=20=EC=88=98=EC=A0=95?=
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

---
 src/test/java/CalcTest.java | 16 +++++++++-------
 1 file changed, 9 insertions(+), 7 deletions(-)

diff --git a/src/test/java/CalcTest.java b/src/test/java/CalcTest.java
index bb948f6a..da335180 100644
--- a/src/test/java/CalcTest.java
+++ b/src/test/java/CalcTest.java
@@ -1,12 +1,14 @@
 
 @DisplayName("계산기 작동 테스트")
 public class CalcTest {
+    private final Calc calc = new Calc();
+
     @Test
     @DisplayName("더하기 테스트")
     void add() {
         final var a = 1;
         final var b = 2;
-        final var actual = a + b;
+        final var actual = calc.add(a, b);
         final var expected = 3;
         
         assertEquals(expected, actual);
@@ -14,10 +16,10 @@ void add() {
 
     @Test
     @DisplayName("빼기 테스트")
-    void add() {
+    void minus() {
         final var a = 3;
         final var b = 1;
-        final var actual = a - b;
+        final var actual = calc.minus(a, b);
         final var expected = 2;
         
         assertEquals(expected, actual);
@@ -25,10 +27,10 @@ void add() {
 
     @Test
     @DisplayName("곱하기 테스트")
-    void add() {
+    void times() {
         final var a = 2;
         final var b = 3;
-        final var actual = a * b;
+        final var actual = calc.times(a, b);
         final var expected = 6;
         
         assertEquals(expected, actual);
@@ -36,10 +38,10 @@ void add() {
 
     @Test
     @DisplayName("나누기 테스트")
-    void add() {
+    void divide() {
         final var a = 10;
         final var b = 5;
-        final var actual = a / b;
+        final var actual = calc.divide(a, b);
         final var expected = 2;
         
         assertEquals(expected, actual);

From 6d40dcf523b4e2652b85dbed0b4236aed2956e01 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?=EB=B0=95=ED=83=9C=EC=A7=84?=
 <140797244+taejinn@users.noreply.github.com>
Date: Thu, 31 Jul 2025 19:38:53 +0900
Subject: [PATCH 05/13] =?UTF-8?q?test:=20=EB=AC=B8=EC=9E=90=EC=97=B4=20?=
 =?UTF-8?q?=EA=B3=84=EC=82=B0=EA=B8=B0=20=ED=85=8C=EC=8A=A4=ED=8A=B8=20?=
 =?UTF-8?q?=EC=B6=94=EA=B0=80?=
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

---
 src/test/java/StringCalcTest.java | 85 +++++++++++++++++++++++++++++++
 1 file changed, 85 insertions(+)
 create mode 100644 src/test/java/StringCalcTest.java

diff --git a/src/test/java/StringCalcTest.java b/src/test/java/StringCalcTest.java
new file mode 100644
index 00000000..349ee4d1
--- /dev/null
+++ b/src/test/java/StringCalcTest.java
@@ -0,0 +1,85 @@
+
+import org.junit.jupiter.api.DisplayName;
+import org.junit.jupiter.api.Test;
+import static org.junit.jupiter.api.Assertions.*;
+
+@DisplayName("문자열 계산기 테스트")
+class StringCalcTest {
+    private final StringCalc stringCalc = new StringCalc();
+
+    @Test
+    @DisplayName("쉼표 구분자 문자열 계산 테스트")
+    void addWithComma() {
+        final var input = "1,2,3";
+        final var actual = stringCalc.add(input);
+        final var expected = 6;
+        
+        assertEquals(expected, actual);
+    }
+
+    @Test
+    @DisplayName("콜론 구분자 문자열 계산 테스트")
+    void addWithColon() {
+        final var input = "1:2:3";
+        final var actual = stringCalc.add(input);
+        final var expected = 6;
+        
+        assertEquals(expected, actual);
+    }
+
+    @Test
+    @DisplayName("쉼표와 콜론 혼합 구분자 테스트")
+    void addWithMixedDelimiters() {
+        final var input = "1,2:3";
+        final var actual = stringCalc.add(input);
+        final var expected = 6;
+        
+        assertEquals(expected, actual);
+    }
+
+    @Test
+    @DisplayName("빈 문자열 테스트")
+    void addEmptyString() {
+        final var input = "";
+        final var actual = stringCalc.add(input);
+        final var expected = 0;
+        
+        assertEquals(expected, actual);
+    }
+
+    @Test
+    @DisplayName("null 입력 테스트")
+    void addNullInput() {
+        final String input = null;
+        final var actual = stringCalc.add(input);
+        final var expected = 0;
+        
+        assertEquals(expected, actual);
+    }
+
+    @Test
+    @DisplayName("커스텀 구분자 테스트")
+    void addWithCustomDelimiter() {
+        final var input = "//;\n1;2;3";
+        final var actual = stringCalc.add(input);
+        final var expected = 6;
+        
+        assertEquals(expected, actual);
+    }
+
+    @Test
+    @DisplayName("음수 입력 예외 테스트")
+    void addNegativeNumberThrowsException() {
+        final var input = "1,-2,3";
+        
+        assertThrows(RuntimeException.class, () -> stringCalc.add(input));
+    }
+
+    @Test
+    @DisplayName("숫자가 아닌 값 입력 예외 테스트")
+    void addNonNumericValueThrowsException() {
+        final var input = "1,a,3";
+        
+        assertThrows(RuntimeException.class, () -> stringCalc.add(input));
+    }
+}
\ No newline at end of file

From 6201b5ad5fc749e18baca0c9b0375e21662ad8ae Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?=EB=B0=95=ED=83=9C=EC=A7=84?=
 <140797244+taejinn@users.noreply.github.com>
Date: Thu, 31 Jul 2025 19:40:10 +0900
Subject: [PATCH 06/13] =?UTF-8?q?refactor:=20assertj=20=EC=B6=94=EA=B0=80?=
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

---
 build.gradle | 1 +
 1 file changed, 1 insertion(+)

diff --git a/build.gradle b/build.gradle
index 87254a3a..be94fd7e 100644
--- a/build.gradle
+++ b/build.gradle
@@ -12,6 +12,7 @@ repositories {
 dependencies {
     testImplementation platform('org.junit:junit-bom:5.9.1')
     testImplementation('org.junit.jupiter:junit-jupiter')
+    testImplementation('org.assertj:assertj-core')
 }
 
 test {

From 0985a9a2654d3e8b17a752ea5d00a0f679cfaab3 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?=EB=B0=95=ED=83=9C=EC=A7=84?=
 <140797244+taejinn@users.noreply.github.com>
Date: Thu, 31 Jul 2025 19:43:08 +0900
Subject: [PATCH 07/13] =?UTF-8?q?refactor:=20junit=20=ED=85=8C=EC=8A=A4?=
 =?UTF-8?q?=ED=8A=B8=20=EC=BD=94=EB=93=9C=EB=A5=BC=20assertj=20=EB=A1=9C?=
 =?UTF-8?q?=20=EC=9E=AC=EC=9E=91=EC=84=B1?=
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

---
 src/test/java/CalcTest.java       | 27 +++++++++++++++++++--------
 src/test/java/StringCalcTest.java | 28 +++++++++++++---------------
 2 files changed, 32 insertions(+), 23 deletions(-)

diff --git a/src/test/java/CalcTest.java b/src/test/java/CalcTest.java
index da335180..f19a6662 100644
--- a/src/test/java/CalcTest.java
+++ b/src/test/java/CalcTest.java
@@ -1,4 +1,8 @@
 
+import org.junit.jupiter.api.DisplayName;
+import org.junit.jupiter.api.Test;
+import static org.assertj.core.api.Assertions.*;
+
 @DisplayName("계산기 작동 테스트")
 public class CalcTest {
     private final Calc calc = new Calc();
@@ -9,9 +13,8 @@ void add() {
         final var a = 1;
         final var b = 2;
         final var actual = calc.add(a, b);
-        final var expected = 3;
         
-        assertEquals(expected, actual);
+        assertThat(actual).isEqualTo(3);
     }
 
     @Test
@@ -20,9 +23,8 @@ void minus() {
         final var a = 3;
         final var b = 1;
         final var actual = calc.minus(a, b);
-        final var expected = 2;
         
-        assertEquals(expected, actual);
+        assertThat(actual).isEqualTo(2);
     }
 
     @Test
@@ -31,9 +33,8 @@ void times() {
         final var a = 2;
         final var b = 3;
         final var actual = calc.times(a, b);
-        final var expected = 6;
         
-        assertEquals(expected, actual);
+        assertThat(actual).isEqualTo(6);
     }
 
     @Test
@@ -42,8 +43,18 @@ void divide() {
         final var a = 10;
         final var b = 5;
         final var actual = calc.divide(a, b);
-        final var expected = 2;
         
-        assertEquals(expected, actual);
+        assertThat(actual).isEqualTo(2);
+    }
+
+    @Test
+    @DisplayName("0으로 나누기 예외 테스트")
+    void divideByZeroThrowsException() {
+        final var a = 10;
+        final var b = 0;
+        
+        assertThatThrownBy(() -> calc.divide(a, b))
+            .isInstanceOf(IllegalArgumentException.class)
+            .hasMessage("0 으로 나눌 수 없습니다.");
     }
 }
\ No newline at end of file
diff --git a/src/test/java/StringCalcTest.java b/src/test/java/StringCalcTest.java
index 349ee4d1..93cc07e0 100644
--- a/src/test/java/StringCalcTest.java
+++ b/src/test/java/StringCalcTest.java
@@ -1,7 +1,7 @@
 
 import org.junit.jupiter.api.DisplayName;
 import org.junit.jupiter.api.Test;
-import static org.junit.jupiter.api.Assertions.*;
+import static org.assertj.core.api.Assertions.*;
 
 @DisplayName("문자열 계산기 테스트")
 class StringCalcTest {
@@ -12,9 +12,8 @@ class StringCalcTest {
     void addWithComma() {
         final var input = "1,2,3";
         final var actual = stringCalc.add(input);
-        final var expected = 6;
         
-        assertEquals(expected, actual);
+        assertThat(actual).isEqualTo(6);
     }
 
     @Test
@@ -22,9 +21,8 @@ void addWithComma() {
     void addWithColon() {
         final var input = "1:2:3";
         final var actual = stringCalc.add(input);
-        final var expected = 6;
         
-        assertEquals(expected, actual);
+        assertThat(actual).isEqualTo(6);
     }
 
     @Test
@@ -32,9 +30,8 @@ void addWithColon() {
     void addWithMixedDelimiters() {
         final var input = "1,2:3";
         final var actual = stringCalc.add(input);
-        final var expected = 6;
         
-        assertEquals(expected, actual);
+        assertThat(actual).isEqualTo(6);
     }
 
     @Test
@@ -42,9 +39,8 @@ void addWithMixedDelimiters() {
     void addEmptyString() {
         final var input = "";
         final var actual = stringCalc.add(input);
-        final var expected = 0;
         
-        assertEquals(expected, actual);
+        assertThat(actual).isEqualTo(0);
     }
 
     @Test
@@ -52,9 +48,8 @@ void addEmptyString() {
     void addNullInput() {
         final String input = null;
         final var actual = stringCalc.add(input);
-        final var expected = 0;
         
-        assertEquals(expected, actual);
+        assertThat(actual).isEqualTo(0);
     }
 
     @Test
@@ -62,9 +57,8 @@ void addNullInput() {
     void addWithCustomDelimiter() {
         final var input = "//;\n1;2;3";
         final var actual = stringCalc.add(input);
-        final var expected = 6;
         
-        assertEquals(expected, actual);
+        assertThat(actual).isEqualTo(6);
     }
 
     @Test
@@ -72,7 +66,9 @@ void addWithCustomDelimiter() {
     void addNegativeNumberThrowsException() {
         final var input = "1,-2,3";
         
-        assertThrows(RuntimeException.class, () -> stringCalc.add(input));
+        assertThatThrownBy(() -> stringCalc.add(input))
+            .isInstanceOf(RuntimeException.class)
+            .hasMessage("음수는 입력할 수 없습니다.");
     }
 
     @Test
@@ -80,6 +76,8 @@ void addNegativeNumberThrowsException() {
     void addNonNumericValueThrowsException() {
         final var input = "1,a,3";
         
-        assertThrows(RuntimeException.class, () -> stringCalc.add(input));
+        assertThatThrownBy(() -> stringCalc.add(input))
+            .isInstanceOf(RuntimeException.class)
+            .hasMessage("숫자 이외의 값이 포함되어 있습니다.");
     }
 }
\ No newline at end of file

From b04a5a0ba0c52f47254177c24037455a073b526e Mon Sep 17 00:00:00 2001
From: PARK TAEJIN <140797244+taejinn@users.noreply.github.com>
Date: Sun, 3 Aug 2025 00:09:15 +0900
Subject: [PATCH 08/13] =?UTF-8?q?fix:=20=ED=95=84=EC=9A=94=20=EC=97=86?=
 =?UTF-8?q?=EB=8A=94=20=EB=B6=80=EB=B6=84=20=EC=A0=9C=EA=B1=B0?=
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

---
 src/main/java/Calc.java | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/src/main/java/Calc.java b/src/main/java/Calc.java
index 83fc66d4..381c6173 100644
--- a/src/main/java/Calc.java
+++ b/src/main/java/Calc.java
@@ -15,7 +15,7 @@ public int times(int a, int b) {
     }
 
     public int divide(int a, int b) {
-        if (a == 0 || b == 0) {
+        if (b == 0) {
             throw new IllegalArgumentException("0 으로 나눌 수 없습니다.");
         }
         int res = a / b;

From 24b236a7d4ab7f4816347ebe0918fb8545990ff8 Mon Sep 17 00:00:00 2001
From: PARK TAEJIN <140797244+taejinn@users.noreply.github.com>
Date: Sun, 3 Aug 2025 00:11:42 +0900
Subject: [PATCH 09/13] =?UTF-8?q?refactor:=20=EC=83=81=EC=88=98=20?=
 =?UTF-8?q?=EB=B3=80=EC=88=98=20=EC=9D=B4=EB=A6=84=20=EB=B3=80=EA=B2=BD?=
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

---
 src/main/java/StringCalc.java | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/src/main/java/StringCalc.java b/src/main/java/StringCalc.java
index 5a698229..a5edf308 100644
--- a/src/main/java/StringCalc.java
+++ b/src/main/java/StringCalc.java
@@ -3,14 +3,14 @@
 
 public class StringCalc {
 
-    private static final String defaultDelimiters = "[,:]";
+    private static final String DEFAULT_DELIMITERS = "[,:]";
 
     public int add(String text) {
         if (text == null || text.isEmpty()) {
             return 0;
         }
 
-        String delimiters = defaultDelimiters;
+        String delimiters = DEFAULT_DELIMITERS;
         String actualTextToParse = text;
 
         Pattern customDelimiterPattern = Pattern.compile("//(.)\n(.*)");

From 82b005c970e4eb731ac83dbcb96742213b8f0306 Mon Sep 17 00:00:00 2001
From: PARK TAEJIN <140797244+taejinn@users.noreply.github.com>
Date: Sun, 3 Aug 2025 00:15:20 +0900
Subject: [PATCH 10/13] =?UTF-8?q?fix:=20=EB=B9=8C=EB=93=9C=20=EC=98=A4?=
 =?UTF-8?q?=EB=A5=98=20=EC=88=98=EC=A0=95?=
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

---
 build.gradle | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/build.gradle b/build.gradle
index be94fd7e..8102a907 100644
--- a/build.gradle
+++ b/build.gradle
@@ -12,7 +12,7 @@ repositories {
 dependencies {
     testImplementation platform('org.junit:junit-bom:5.9.1')
     testImplementation('org.junit.jupiter:junit-jupiter')
-    testImplementation('org.assertj:assertj-core')
+    testImplementation('org.assertj:assertj-core:3.24.2')
 }
 
 test {

From 4eb89d11f9ed3cec2e9e98aaf32695af64eeaa3b Mon Sep 17 00:00:00 2001
From: PARK TAEJIN <140797244+taejinn@users.noreply.github.com>
Date: Sun, 3 Aug 2025 00:29:08 +0900
Subject: [PATCH 11/13] =?UTF-8?q?refactor:=20=EB=8B=A8=EC=9D=BC=20?=
 =?UTF-8?q?=EC=B1=85=EC=9E=84=20=EC=9B=90=EC=B9=99=20=EB=B0=98=EC=98=81?=
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

---
 src/main/java/StringCalc.java | 64 +++++++++++++++++++++++++----------
 1 file changed, 47 insertions(+), 17 deletions(-)

diff --git a/src/main/java/StringCalc.java b/src/main/java/StringCalc.java
index a5edf308..d7b10db9 100644
--- a/src/main/java/StringCalc.java
+++ b/src/main/java/StringCalc.java
@@ -6,41 +6,71 @@ public class StringCalc {
     private static final String DEFAULT_DELIMITERS = "[,:]";
 
     public int add(String text) {
-        if (text == null || text.isEmpty()) {
+        if (isNullOrEmpty(text)) {
             return 0;
         }
 
-        String delimiters = DEFAULT_DELIMITERS;
-        String actualTextToParse = text;
+        DelimiterInfo delimiterInfo = parseDelimiterInfo(text);
+        String[] numbersAsString = splitByDelimiter(delimiterInfo.textToParse, delimiterInfo.delimiter);
+        
+        return calculateSum(numbersAsString);
+    }
+
+    private boolean isNullOrEmpty(String text) {
+        return text == null || text.isEmpty();
+    }
 
+    private DelimiterInfo parseDelimiterInfo(String text) {
         Pattern customDelimiterPattern = Pattern.compile("//(.)\n(.*)");
         Matcher matcher = customDelimiterPattern.matcher(text);
 
         if (matcher.find()) {
             String customDelimiter = Pattern.quote(matcher.group(1));
-            delimiters = customDelimiter;
-            actualTextToParse = matcher.group(2);
+            String actualTextToParse = matcher.group(2);
+            return new DelimiterInfo(customDelimiter, actualTextToParse);
         }
 
-        String[] numbersAsString = actualTextToParse.split(delimiters);
-        int sum = 0;
+        return new DelimiterInfo(DEFAULT_DELIMITERS, text);
+    }
 
+    private String[] splitByDelimiter(String text, String delimiter) {
+        return text.split(delimiter);
+    }
+
+    private int calculateSum(String[] numbersAsString) {
+        int sum = 0;
         for (String numStr : numbersAsString) {
             if (numStr.isEmpty()) {
                 continue;
             }
+            sum += parseAndValidateNumber(numStr);
+        }
+        return sum;
+    }
 
-            try {
-                int number = Integer.parseInt(numStr);
+    private int parseAndValidateNumber(String numStr) {
+        try {
+            int number = Integer.parseInt(numStr);
+            validateNumber(number);
+            return number;
+        } catch (NumberFormatException e) {
+            throw new RuntimeException("숫자 이외의 값이 포함되어 있습니다.");
+        }
+    }
 
-                if (number < 0) {
-                    throw new RuntimeException("음수는 입력할 수 없습니다.");
-                }
-                sum += number;
-            } catch (NumberFormatException e) {
-                throw new RuntimeException("숫자 이외의 값이 포함되어 있습니다.");
-            }
+    private void validateNumber(int number) {
+        if (number < 0) {
+            throw new RuntimeException("음수는 입력할 수 없습니다.");
+        }
+    }
+
+    private static class DelimiterInfo {
+        final String delimiter;
+        final String textToParse;
+
+        DelimiterInfo(String delimiter, String textToParse) {
+            this.delimiter = delimiter;
+            this.textToParse = textToParse;
         }
-        return sum;
     }
 }
\ No newline at end of file

From f095ad05d4455fd0a5166107ed963f1bbeae7ced Mon Sep 17 00:00:00 2001
From: PARK TAEJIN <140797244+taejinn@users.noreply.github.com>
Date: Sun, 3 Aug 2025 00:33:54 +0900
Subject: [PATCH 12/13] =?UTF-8?q?fix:=20=EC=BB=A4=EC=8A=A4=ED=85=80=20?=
 =?UTF-8?q?=EA=B5=AC=EB=B6=84=EC=9E=90=20=EC=82=AC=EC=9A=A9=20=EC=8B=9C=20?=
 =?UTF-8?q?=EA=B8=B0=EB=B3=B8=20=EA=B5=AC=EB=B6=84=EC=9E=90=EB=A5=BC=20?=
 =?UTF-8?q?=EB=AC=B8=EC=9E=90=EB=A1=9C=20=EB=B3=B4=EB=8A=94=20=EB=AC=B8?=
 =?UTF-8?q?=EC=A0=9C?=
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

---
 src/main/java/StringCalc.java | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/src/main/java/StringCalc.java b/src/main/java/StringCalc.java
index d7b10db9..55af9585 100644
--- a/src/main/java/StringCalc.java
+++ b/src/main/java/StringCalc.java
@@ -27,7 +27,9 @@ private DelimiterInfo parseDelimiterInfo(String text) {
         if (matcher.find()) {
             String customDelimiter = Pattern.quote(matcher.group(1));
             String actualTextToParse = matcher.group(2);
-            return new DelimiterInfo(customDelimiter, actualTextToParse);
+            // 커스텀 구분자와 기본 구분자를 모두 포함
+            String combinedDelimiters = DEFAULT_DELIMITERS + "|" + customDelimiter;
+            return new DelimiterInfo(combinedDelimiters, actualTextToParse);
         }
 
         return new DelimiterInfo(DEFAULT_DELIMITERS, text);

From 3e68faa27eb74c11873bdb526600ac38109c896e Mon Sep 17 00:00:00 2001
From: PARK TAEJIN <140797244+taejinn@users.noreply.github.com>
Date: Sun, 3 Aug 2025 00:34:16 +0900
Subject: [PATCH 13/13] =?UTF-8?q?test:=20=EC=BB=A4=EC=8A=A4=ED=85=80=20?=
 =?UTF-8?q?=EA=B5=AC=EB=B6=84=EC=9E=90=EC=99=80=20=EA=B8=B0=EB=B3=B8=20?=
 =?UTF-8?q?=EA=B5=AC=EB=B6=84=EC=9E=90=20=ED=98=BC=ED=95=A9=20=ED=85=8C?=
 =?UTF-8?q?=EC=8A=A4=ED=8A=B8=20=EC=B6=94=EA=B0=80?=
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

---
 src/test/java/StringCalcTest.java | 9 +++++++++
 1 file changed, 9 insertions(+)

diff --git a/src/test/java/StringCalcTest.java b/src/test/java/StringCalcTest.java
index 93cc07e0..9cdb0195 100644
--- a/src/test/java/StringCalcTest.java
+++ b/src/test/java/StringCalcTest.java
@@ -80,4 +80,13 @@ void addNonNumericValueThrowsException() {
             .isInstanceOf(RuntimeException.class)
             .hasMessage("숫자 이외의 값이 포함되어 있습니다.");
     }
+
+    @Test
+    @DisplayName("커스텀 구분자와 기본 구분자 혼합 테스트")
+    void addWithCustomAndDefaultDelimiters() {
+        final var input = "//@\n1@2,3:4";
+        final var actual = stringCalc.add(input);
+        
+        assertThat(actual).isEqualTo(10);
+    }
 }
\ No newline at end of file