Step2 (#5940)

* StringAddCalculator

* StringAddCalculator

* apply review

Author: HanSangKkyu

src/main/java/StringAddCalculator.java

@@ -0,0 +1,59 @@
+import java.util.Arrays;
+import java.util.Objects;
+import java.util.regex.Matcher;
+import java.util.regex.Pattern;
+
+public class StringAddCalculator {
+
+    public static final String DELIMITER = ",|:";
+    public static final String CUSTOM_DELIMITER_REGEX = "//(.)\n(.*)";
+    public static final Pattern PATTERN = Pattern.compile(CUSTOM_DELIMITER_REGEX);
+    public static final int CUSTOM_DELIMITER_GROUP = 1;
+    public static final int TEXT_TOKEN_GROUP = 2;
+
+    public static int splitAndSum(String text) {
+        if (isNullOrBlank(text)) {
+            return 0;
+        }
+        final Matcher matcher = PATTERN.matcher(text);
+        if (matcher.find()) {
+            final String customDelimiter = matcher.group(CUSTOM_DELIMITER_GROUP);
+            final String textToken = matcher.group(TEXT_TOKEN_GROUP);
+            return sum(validateNegative(toInts(split(textToken, customDelimiter))));
+        }
+        return sum(validateNegative(toInts(split(text, DELIMITER))));
+    }
+
+    private static boolean isNullOrBlank(String text) {
+        return Objects.isNull(text) || text.isBlank();
+    }
+
+    private static String[] split(String text, String delimiter) {
+        return text.split(delimiter);
+    }
+
+    private static int[] toInts(String[] values) {
+        final int[] result = new int[values.length];
+        for (int i = 0; i < values.length; i++) {
+            result[i] = getParseInt(values[i]);
+        }
+        return result;
+    }
+
+    private static int[] validateNegative(int[] values) {
+        for (int value : values) {
+            if (value < 0) {
+                throw new RuntimeException("have negative value");
+            }
+        }
+        return values;
+    }
+
+    private static int getParseInt(String values) {
+        return Integer.parseInt(values);
+    }
+
+    private static int sum(int[] values) {
+        return Arrays.stream(values).sum();
+    }
+}

src/test/java/StringAddCalculatorTest.java

@@ -0,0 +1,58 @@
+import org.junit.jupiter.api.DisplayName;
+import org.junit.jupiter.api.Test;
+
+import static org.assertj.core.api.Assertions.assertThat;
+import static org.assertj.core.api.Assertions.assertThatThrownBy;
+
+public class StringAddCalculatorTest {
+    @Test
+    @DisplayName("null_또는_빈문자가_입력으로_들어오면_무조건_0_리턴")
+    public void nullOrBlankTest() {
+        int result = StringAddCalculator.splitAndSum(null);
+        assertThat(result).isEqualTo(0);
+
+        result = StringAddCalculator.splitAndSum("");
+        assertThat(result).isEqualTo(0);
+
+        result = StringAddCalculator.splitAndSum(" ");
+        assertThat(result).isEqualTo(0);
+    }
+
+    @Test
+    @DisplayName("숫자_하나가_입력으로_들어와도_정상적으로_숫자합이_계산된다")
+    void singleNumTest() {
+        final int actual = StringAddCalculator.splitAndSum("1");
+        assertThat(actual).isEqualTo(1);
+    }
+
+    @Test
+    @DisplayName("컴마 구분자가 포함된 문자열을 입력으로 받았을 때 정상동작한다")
+    void commaTest() {
+        assertThat(StringAddCalculator.splitAndSum("1,2")).isEqualTo(3);
+    }
+
+    @Test
+    @DisplayName("콜론 구분자가 포함된 문자열을 입력으로 받았을 때 정상동작한다")
+    void colonsTest() {
+        assertThat(StringAddCalculator.splitAndSum("1:2")).isEqualTo(3);
+    }
+
+    @Test
+    @DisplayName("컴마와 콜론 구분자가 포함된 문자열을 입력으로 받았을 때 정상동작한다")
+    void commaColonsTest() {
+        assertThat(StringAddCalculator.splitAndSum("1:2,3")).isEqualTo(6);
+    }
+
+    @Test
+    @DisplayName("커스텀 구분자가 포함된 문자열을 입력으로 받았을 때 정상동작한다")
+    void customDelimiter() {
+        assertThat(StringAddCalculator.splitAndSum("//;\n1;2;3")).isEqualTo(6);
+    }
+
+    @Test
+    @DisplayName("음수가 포함된 문자열을 입력으로 받았을 때 RuntimeException이 발생한다")
+    public void splitAndSum_negative() {
+        assertThatThrownBy(() -> StringAddCalculator.splitAndSum("-1,2,3"))
+                .isInstanceOf(RuntimeException.class);
+    }
+}