Step1 : 문자열 덧셈 계산기

src/main/java/racingcar/Car.java

@@ -6,19 +6,19 @@ public class Car {
 
     public Car(final String name) {
         if (name.length() > 5) {
-            throw new IllegalArgumentException();
+            throw new IllegalArgumentException("이름은 5글자를 넘을 수 없습니다");
         }
 
         this.name = name;
     }
 
-    public int getPosition() {
-        return position;
-    }
-
     public void move(final MovingStrategy movingStrategy) {
         if (movingStrategy.movable()) {
             position++;
         }
     }
+
+    public int getPosition() {
+        return position;
+    }
 }

src/main/kotlin/stringcalculator/ExpressionMatcher.kt

@@ -0,0 +1,32 @@
+package stringcalculator
+
+import java.util.regex.Pattern
+
+class ExpressionMatcher {
+
+    fun transform(expressionStr: String): Expression {
+        val matcher = CUSTOM_DELIMITER_PATTERN.matcher(expressionStr)
+
+        return if (matcher.find()) {
+            Expression(
+                input = matcher.group(2),
+                delimiters = DEFAULT_DELIMITER + matcher.group(1),
+            )
+        } else {
+            Expression(
+                input = expressionStr,
+                delimiters = DEFAULT_DELIMITER,
+            )
+        }
+    }
+
+    companion object {
+        private val DEFAULT_DELIMITER = listOf(",", ":")
+        private val CUSTOM_DELIMITER_PATTERN = Pattern.compile("//(.)\n(.*)")
+
+        data class Expression(
+            val delimiters: List<String>,
+            val input: String,
+        )
+    }
+}

src/main/kotlin/stringcalculator/NumberTokenizer.kt

@@ -0,0 +1,18 @@
+package stringcalculator
+
+import stringcalculator.ExpressionMatcher.Companion.Expression
+
+class NumberTokenizer {
+
+    fun tokenize(expression: Expression): List<Int> {
+        val numberTokens = splitNumberTokens(expression.input, expression.delimiters)
+        val numbers = numberTokens.map { it.toInt() }
+
+        return numbers
+    }
+
+    private fun splitNumberTokens(input: String, delimiters: List<String>): List<String> {
+        return if (delimiters.isEmpty()) listOf(input)
+        else input.split(delimiters.joinToString("|").toRegex())
+    }
+}

src/main/kotlin/stringcalculator/StringCalculator.kt

@@ -0,0 +1,27 @@
+package stringcalculator
+
+class StringCalculator {
+
+    private val expressionMatcher = ExpressionMatcher()
+    private val numberTokenizer = NumberTokenizer()
+
+    fun calculate(calculatorExpression: String?): Int {
+        if (calculatorExpression.isNullOrEmpty()) return DEFAULT_VALUE
+
+        val expression = expressionMatcher.transform(calculatorExpression)
+        val numbers = numberTokenizer.tokenize(expression)
+        validateNegativeValue(numbers)
+
+        return numbers.sum()
+    }
+
+    private fun validateNegativeValue(tokens: List<Int>) {
+        if (tokens.any { it < 0 }) {
+            throw RuntimeException("음수의 덧셈은 제공하지 않는 기능입니다")
+        }
+    }
+
+    companion object {
+        private const val DEFAULT_VALUE = 0
+    }
+}

src/test/kotlin/stringcalculator/ExpressionMatcherTest.kt

@@ -0,0 +1,54 @@
+package stringcalculator
+
+import org.assertj.core.api.Assertions.assertThat
+import org.junit.jupiter.api.DisplayName
+import org.junit.jupiter.api.Test
+import stringcalculator.ExpressionMatcher.Companion.Expression
+
+internal class ExpressionMatcherTest {
+
+    private val sut = ExpressionMatcher()
+
+    @DisplayName("커스텀 구분자가 없을경우 기본 구분자로 쉼표(,)와 콜론(:)을 포함시킨다")
+    @Test
+    fun useDefaultDelimiterIfNoCustomDelimiter() {
+        // given
+        val expressionInput = "1:2,3"
+
+        // when
+        val actual = sut.transform(expressionInput)
+
+        // then
+        assertThat(actual).isEqualTo(Expression(DEFAULT_DELIMITERS, expressionInput))
+    }
+
+    @DisplayName("커스텀 구분자는 //와 \n 문자 사이에 지정해 Expression에 포함할 수 있다")
+    @Test
+    fun useCustomDelimiterIfHaveCustomDelimiterInput() {
+        // given
+        val expressionInput = "//;\n1:2,3;4"
+
+        // when
+        val actual = sut.transform(expressionInput)
+
+        // then
+        assertThat(actual).isEqualTo(Expression(listOf(*DEFAULT_DELIMITERS.toTypedArray(), ";"), "1:2,3;4"))
+    }
+
+    @DisplayName("커스텀 구분자 이외의 모든 문자열을 입력으로 변환한다")
+    @Test
+    fun useAllInputIfNoDelimiter() {
+        // given
+        val expressionInput = ",a;2:3,12"
+
+        // when
+        val actual = sut.transform(expressionInput)
+
+        // then
+        assertThat(actual).isEqualTo(Expression(DEFAULT_DELIMITERS, ",a;2:3,12"))
+    }
+
+    companion object {
+        private val DEFAULT_DELIMITERS = listOf(",", ":")
+    }
+}

src/test/kotlin/stringcalculator/NumberTokenizerTest.kt

@@ -0,0 +1,66 @@
+package stringcalculator
+
+import org.assertj.core.api.Assertions.assertThat
+import org.junit.jupiter.api.DisplayName
+import org.junit.jupiter.api.Test
+import org.junit.jupiter.params.ParameterizedTest
+import org.junit.jupiter.params.provider.Arguments
+import org.junit.jupiter.params.provider.MethodSource
+import stringcalculator.ExpressionMatcher.Companion.Expression
+
+internal class NumberTokenizerTest {
+
+    private val sut = NumberTokenizer()
+
+    @DisplayName("숫자로 변환할 수 없을경우 NumberFormatException 예외가 발생한다")
+    @Test
+    fun errorIfNoNumberFormat() {
+        // given
+        val delimiters = listOf(":")
+        val input = "1:asdf"
+        val expr = Expression(delimiters, input)
+
+        // when
+        val actual = kotlin.runCatching { sut.tokenize(expr) }
+
+        // then
+        assertThat(actual.exceptionOrNull()).isInstanceOf(NumberFormatException::class.java)
+    }
+
+    @DisplayName("구분자가 없을경우 입력된 문자열 자체를 숫자로 변환한다")
+    @Test
+    fun parseNumberIfNoDelimiter() {
+        // given
+        val delimiters = emptyList<String>()
+        val input = "12345"
+
+        // when
+        val actual = sut.tokenize(Expression(delimiters, input))
+
+        // then
+        assertThat(actual).isEqualTo(listOf(12345))
+    }
+
+    @DisplayName("입력된 문자열을 구분자를 통해 나눈다")
+    @ParameterizedTest
+    @MethodSource("provideDelimiterSource")
+    fun tokenize(delimiters: List<String>, input: String, answer: List<Int>) {
+        // given
+        val exp = Expression(delimiters, input)
+
+        // when
+        val actual = sut.tokenize(exp)
+
+        // then
+        assertThat(actual).isEqualTo(answer)
+    }
+
+    companion object {
+        @JvmStatic
+        fun provideDelimiterSource() = listOf(
+            Arguments.of(listOf(":"), "1:2:3", listOf(1, 2, 3)),
+            Arguments.of(listOf(":", ","), "1:2,3", listOf(1, 2, 3)),
+            Arguments.of(listOf("=", ",", ":"), "1=2,3:4", listOf(1, 2, 3, 4)),
+        )
+    }
+}

src/test/kotlin/stringcalculator/StringCalculatorTest.kt

@@ -0,0 +1,77 @@
+package stringcalculator
+
+import org.assertj.core.api.Assertions.assertThat
+import org.assertj.core.api.Assertions.assertThatExceptionOfType
+import org.junit.jupiter.api.DisplayName
+import org.junit.jupiter.params.ParameterizedTest
+import org.junit.jupiter.params.provider.Arguments
+import org.junit.jupiter.params.provider.MethodSource
+import org.junit.jupiter.params.provider.NullAndEmptySource
+import org.junit.jupiter.params.provider.ValueSource
+
+internal class StringCalculatorTest {
+
+    private val sut = StringCalculator()
+
+    @DisplayName(value = "빈 문자열 또는 null 값을 입력할 경우 0을 반환해야 한다.")
+    @ParameterizedTest
+    @NullAndEmptySource
+    fun emptyOrNull(text: String?) {
+        assertThat(sut.calculate(text)).isZero
+    }
+
+    @DisplayName(value = "숫자 하나를 문자열로 입력할 경우 해당 숫자를 반환한다.")
+    @ParameterizedTest
+    @ValueSource(strings = ["1"])
+    fun oneNumber(text: String) {
+        assertThat(sut.calculate(text)).isSameAs(text.toInt())
+    }
+
+    @DisplayName(value = "숫자 두개를 쉼표(,) 구분자로 입력할 경우 두 숫자의 합을 반환한다.")
+    @ParameterizedTest
+    @ValueSource(strings = ["1,2"])
+    fun twoNumbers(text: String?) {
+        assertThat(sut.calculate(text)).isSameAs(3)
+    }
+
+    @DisplayName(value = "구분자를 쉼표(,) 이외에 콜론(:)을 사용할 수 있다.")
+    @ParameterizedTest
+    @ValueSource(strings = ["1,2:3"])
+    fun colons(text: String?) {
+        assertThat(sut.calculate(text)).isSameAs(6)
+    }
+
+    @DisplayName(value = "//와 \\n 문자 사이에 커스텀 구분자를 지정할 수 있다.")
+    @ParameterizedTest
+    @ValueSource(strings = ["//;\n1;2;3"])
+    fun customDelimiter(text: String?) {
+        assertThat(sut.calculate(text)).isSameAs(6)
+    }
+
+    @DisplayName(value = "문자열 계산기에 음수를 전달하는 경우 RuntimeException 예외 처리를 한다.")
+    @ParameterizedTest
+    @ValueSource(strings = ["-1", "1:-3", "3,5,7:-29"])
+    fun negative(text: String) {
+        assertThatExceptionOfType(RuntimeException::class.java).isThrownBy {
+            sut.calculate(text)
+        }
+    }
+
+    @DisplayName(value = "문자열 계산기로 합을 계산한다")
+    @ParameterizedTest
+    @MethodSource("provideSumArguments")
+    fun sum(text: String, result: Int) {
+        assertThat(sut.calculate(text)).isSameAs(result)
+    }
+
+    companion object {
+        @JvmStatic
+        fun provideSumArguments() = listOf(
+            Arguments.of("0", 0),
+            Arguments.of("1", 1),
+            Arguments.of("1,3,5", 9),
+            Arguments.of("4:15,25", 44),
+            Arguments.of("//;\n1;2;3,4:5", 15),
+        )
+    }
+}