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Step1 - 문자열 계산기 (#4197)
* feat: 1단계 문자열 계산기 - 초안 구성 * feat: 1단계 문자열 계산기 - 입력값 유효성검사 구현 및 테스트 코드 구현 * feat: 1단계 문자열 계산기 - 관련 내용 구현 및 테스트
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‎src/main/java/calculator/CalculatorFactory.java‎

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package calculator;
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public class CalculatorFactory {
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private static final String ADD = "+";
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private static final String SUB = "-";
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private static final String MULTI = "*";
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private static final String DIV = "/";
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public int handleWayByOperator(String operator, int left, int right) {
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if (operator.equals(ADD)) {
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return add(left, right);
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}
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if (operator.equals(SUB)) {
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return sub(left, right);
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}
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if (operator.equals(MULTI)) {
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return multi(left, right);
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}
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if(operator.equals(DIV)) {
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return div(left, right);
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}
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throw new IllegalArgumentException("사칙연산 기호만 입력 할 수 있습니다");
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}
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public int add(int left, int right) {
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return left + right;
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}
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public int sub(int left, int right) {
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return left - right;
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}
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public int multi(int left, int right) {
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return left * right;
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}
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public int div(int left, int right) {
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return left / right;
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}
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}

‎src/main/java/calculator/CalculatorTokens.java‎

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package calculator;
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import java.util.LinkedList;
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import java.util.List;
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import java.util.Queue;
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public class CalculatorTokens {
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private Queue<String> calculateTokens;
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private final String firstTokenNum;
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public CalculatorTokens(List<String> calculateTokens) {
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if (calculateTokens.isEmpty()) {
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throw new IllegalArgumentException("계산토큰목록을 필수 입니다.");
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}
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this.calculateTokens = new LinkedList<>(calculateTokens);
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this.firstTokenNum = this.calculateTokens.poll();
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}
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public int firstTokenNum() {
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return Integer.parseInt(firstTokenNum);
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}
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public OneTokenBundle getOneTokenBundle() {
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if (calculateTokens.isEmpty()) {
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throw new RuntimeException("계산할 수 있는 토큰이 없습니다");
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}
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return new OneTokenBundle(
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calculateTokens.poll(),
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calculateTokens.poll()
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);
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}
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public boolean hasNext() {
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return !calculateTokens.isEmpty();
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}
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}

‎src/main/java/calculator/InputValidator.java‎

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package calculator;
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import static java.util.Objects.isNull;
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import java.util.List;
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import java.util.Set;
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import java.util.regex.Pattern;
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public class InputValidator {
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private static final String NUM_AND_OPERATOR_DELIMITER = " ";
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private static final Pattern POSITIVE_NUMBER_PATTERN = Pattern.compile("[-+]?\\d*\\.?\\d+");
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private static final Set<String> OPERATORS = Set.of("+", "-", "*", "/");
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public List<String> validAndSplitInput(String input) {
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if (isNull(input) || input.isBlank()) {
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throw new IllegalArgumentException("입력값이 없거나 빈 문자열 입니다");
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}
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String[] inputArrays = trimAndSplit(input);
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if (inputArrays.length < 2) {
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throw new IllegalArgumentException("입력값이 하나이거나 비정상 문자열 입니다");
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}
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for (int index = 0; index < inputArrays.length; index++) {
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validInputByIndex(index, inputArrays);
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}
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return List.of(inputArrays);
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}
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private String[] trimAndSplit(String input) {
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return input.trim().split(NUM_AND_OPERATOR_DELIMITER);
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}
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private boolean isEvenNum(int number) {
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return number % 2 == 0;
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}
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private boolean isOddNum(int number) {
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return number % 2 == 1;
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}
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private void validInputByIndex(int index, String[] inputArrays) {
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if (isEvenNum(index)) {
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validNumber(inputArrays[index]);
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return;
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}
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if (isOddNum(index)) {
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validOperator(inputArrays[index]);
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}
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}
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private void validNumber(String inputArrays) {
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if (!POSITIVE_NUMBER_PATTERN.matcher(inputArrays).matches()) {
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throw new IllegalArgumentException("입력값이 정수가 아닙니다. 정해진 입력값 양식에 맞춰 작성해주세요");
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}
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}
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private void validOperator(String inputArrays) {
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if (!OPERATORS.contains(inputArrays)) {
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throw new IllegalArgumentException("입력값이 연산자가 아닙니다. 정해진 입력값 양식에 맞춰 작성해주세요");
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}
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}
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}

‎src/main/java/calculator/OneTokenBundle.java‎

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package calculator;
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public class OneTokenBundle {
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private final String operator;
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private final String rightNumber;
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public OneTokenBundle(
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String operator,
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String rightNumber
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) {
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this.operator = operator;
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this.rightNumber = rightNumber;
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}
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public String operator() {
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return operator;
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}
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public int rightNumber() {
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return Integer.parseInt(rightNumber);
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}
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}

‎src/main/java/calculator/StringCalculator.java‎

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package calculator;
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import java.util.List;
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/**
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*
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* 기능 요구사항
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* 사용자가 입력한 문자열 값에 따라 사칙연산을 수행할 수 있는 계산기를 구현해야 한다.
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* 입력 문자열의 숫자와 사칙 연산 사이에는 반드시 빈 공백 문자열이 있다고 가정한다.
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* 나눗셈의 경우 결과 값을 정수로 떨어지는 값으로 한정한다.
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* 문자열 계산기는 사칙연산의 계산 우선순위가 아닌 입력 값에 따라 계산 순서가 결정된다. 즉, 수학에서는 곱셈, 나눗셈이 덧셈, 뺄셈 보다 먼저 계산해야 하지만 이를 무시한다.
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* 예를 들어 2 + 3 * 4 / 2와 같은 문자열을 입력할 경우 2 + 3 * 4 / 2 실행 결과인 10을 출력해야 한다.
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*
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* */
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public class StringCalculator {
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private static final String NUM_AND_OPERATOR_DELIMITER = " ";
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private final CalculatorFactory calculatorFactory;
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public StringCalculator(CalculatorFactory calculatorFactory) {
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this.calculatorFactory = calculatorFactory;
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}
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public int calculate(String input) {
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CalculatorTokens calculateTokens = new CalculatorTokens(
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new InputValidator().validAndSplitInput(input)
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);
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int result = calculateTokens.firstTokenNum();
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while (calculateTokens.hasNext()) {
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OneTokenBundle oneTokenBundle = calculateTokens.getOneTokenBundle();
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result = calculatorFactory.handleWayByOperator(
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oneTokenBundle.operator(),
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result,
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oneTokenBundle.rightNumber()
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);
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}
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return result;
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}
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}

‎src/test/java/calculator/CalculatorFactoryTest.java‎

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package calculator;
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import static org.assertj.core.api.Assertions.assertThat;
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import org.junit.jupiter.api.Test;
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class CalculatorFactoryTest {
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@Test
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void 덧셈() {
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CalculatorFactory calculator = new CalculatorFactory();
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assertThat(
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calculator.handleWayByOperator(
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"+",
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1,
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2
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)
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).isEqualTo(3);
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}
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@Test
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void 뺄셈() {
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CalculatorFactory calculator = new CalculatorFactory();
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assertThat(
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calculator.handleWayByOperator(
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"-",
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2,
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1
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)
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).isEqualTo(1);
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}
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@Test
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void 곱셈() {
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CalculatorFactory calculator = new CalculatorFactory();
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assertThat(
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calculator.handleWayByOperator(
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"*",
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2,
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2
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)
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).isEqualTo(4);
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}
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@Test
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void 나눗셈_나머지가_있는경우도_몫만_반환할_수_있다() {
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CalculatorFactory calculator = new CalculatorFactory();
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assertThat(
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calculator.handleWayByOperator(
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"/",
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5,
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2
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)
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).isEqualTo(2);
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}
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@Test
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void 나눗셈_나머지가_없는경우도_몫만_반환할_수_있다() {
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CalculatorFactory calculator = new CalculatorFactory();
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assertThat(
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calculator.handleWayByOperator(
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"/",
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4,
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2
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)
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).isEqualTo(2);
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}
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}

‎src/test/java/calculator/InputValidatorTest.java‎

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package calculator;
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import static org.assertj.core.api.Assertions.assertThatThrownBy;
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import org.junit.jupiter.api.Test;
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import org.junit.jupiter.params.ParameterizedTest;
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import org.junit.jupiter.params.provider.ValueSource;
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class InputValidatorTest {
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@Test
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void 계산기의_입력값이_없는경우_예외처리를_할_수_있다() {
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assertThatThrownBy(() -> new InputValidator().validAndSplitInput(""))
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.isInstanceOf(IllegalArgumentException.class);
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}
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@ParameterizedTest
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@ValueSource(strings = {"1", "1 2", "&"})
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void 구분자로_나눈_입력배열의_길이가_하나이면_예외처리_할_수_있다(String input) {
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assertThatThrownBy(
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() -> new InputValidator().validAndSplitInput(input)
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).isInstanceOf(IllegalArgumentException.class);
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}
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@Test
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void 구분자로_나눈_입력배열중_짝수인덱스가_정수가_아니면_예외처리_할_수_있다() {
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assertThatThrownBy(
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() -> new InputValidator().validAndSplitInput("4 + 5 * /")
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).isInstanceOf(IllegalArgumentException.class);
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}
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@Test
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void 구분자로_나눈_입력배열중_홀수인덱스가_연산자가_아니면_예외처리_할_수_있다() {
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assertThatThrownBy(
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() -> new InputValidator().validAndSplitInput("4 + 5 6 8")
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).isInstanceOf(IllegalArgumentException.class);
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}
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}

‎src/test/java/calculator/StringCalculatorTest.java‎

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package calculator;
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import static org.assertj.core.api.Assertions.assertThat;
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import org.junit.jupiter.api.Test;
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class StringCalculatorTest {
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@Test
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void 사칙연산을_계산할_수_있다() {
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StringCalculator calculator = new StringCalculator(new CalculatorFactory());
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assertThat(
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calculator.calculate("2 + 3 * 4 / 2")
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).isEqualTo(10);
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}
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}

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