step2) 문자열계산기 (#5927)

* step2) 문자열덧셈계산기

* 리뷰 반영

Author: smileeeey

src/main/java/StringPlusCalculator.java

@@ -0,0 +1,21 @@
+import java.util.Arrays;
+
+public class StringPlusCalculator {
+
+    private static String SEPERATOR_REGEX = "//(.*?)\n";
+
+    public int calculate(String input) {
+        if (input == null) {
+            return 0;
+        }
+
+        StringSplitter splitter = StringSplitter.from(input);
+        String[] splited = splitter.getInputString().split("[" + splitter.getSeparator() + "]");
+
+        return Arrays.stream(splited)
+                     .filter(s -> !s.isEmpty())
+                     .mapToInt(Integer::parseInt)
+                     .filter(it -> it > 0)
+                     .sum();
+    }
+}

src/main/java/StringSplitter.java

@@ -0,0 +1,30 @@
+import java.util.regex.Matcher;
+import java.util.regex.Pattern;
+
+public class StringSplitter {
+    private String separator;
+    private String inputString;
+    private static String DEFAULT_SEPARATOR = ",:";
+    public StringSplitter(String separator, String inputString) {
+        this.separator = separator;
+        this.inputString = inputString;
+    }
+
+    public static StringSplitter from(String input) {
+        Pattern pattern = Pattern.compile("//(.+)\n(.*)");
+        Matcher matcher = pattern.matcher(input);
+
+        if (matcher.find()) {
+            return new StringSplitter(matcher.group(1) + DEFAULT_SEPARATOR, matcher.group(2));
+        }
+        return new StringSplitter(DEFAULT_SEPARATOR, input);
+    }
+
+    public String getSeparator() {
+        return separator;
+    }
+
+    public String getInputString() {
+        return inputString;
+    }
+}

src/test/java/StringPlusCalculatorTest.java

@@ -0,0 +1,21 @@
+import org.junit.jupiter.params.ParameterizedTest;
+import org.junit.jupiter.params.provider.CsvSource;
+
+import static org.junit.jupiter.api.Assertions.assertEquals;
+
+class StringPlusCalculatorTest {
+
+    private StringPlusCalculator stringPlusCalculator = new StringPlusCalculator();
+
+    @ParameterizedTest
+    @CsvSource({
+            "'',0",
+            "'1,2',3",
+            "'1,2,3',6",
+            "'1,2:3',6",
+            "'//;\n1;2;3',6",
+    })
+    void seperateByDefault(String input, int result) {
+        assertEquals(result, stringPlusCalculator.calculate(input));
+    }
+}

src/test/java/StringSplitterTest.java

@@ -0,0 +1,28 @@
+import org.junit.jupiter.params.ParameterizedTest;
+import org.junit.jupiter.params.provider.ValueSource;
+
+import static org.junit.jupiter.api.Assertions.assertEquals;
+
+public class StringSplitterTest {
+
+    private static final String DEFAULT_SEPARATOR = ",:";
+
+    private void assertSeparatorAndInput(StringSplitter splitter, String expectedSeparator, String expectedInput) {
+        assertEquals(expectedSeparator, splitter.getSeparator());
+        assertEquals(expectedInput, splitter.getInputString());
+    }
+
+    @ParameterizedTest
+    @ValueSource(strings = {"","1,2","1,2,3","1,2:3"})
+    public void testFromWithoutMatch(String input) {
+        StringSplitter splitter = StringSplitter.from(input);
+        assertSeparatorAndInput(splitter, DEFAULT_SEPARATOR, input);
+    }
+
+    @ParameterizedTest
+    @ValueSource(strings = "//;\n1;2;3")
+    public void testFromWithMatch(String input) {
+        StringSplitter splitter = StringSplitter.from(input);
+        assertSeparatorAndInput(splitter, ";,:", "1;2;3");
+    }
+}