refactoring : shotgun surgery - move field

refactoring/src/main/java/com/example/refactoring/_08_shotgun_surgery/_27_move_field/Customer.java

@@ -0,0 +1,38 @@
+package com.example.refactoring._08_shotgun_surgery._27_move_field;
+
+import java.math.BigDecimal;
+import java.time.LocalDate;
+
+public class Customer {
+
+    private String name;
+
+    private CustomerContract contract;
+
+    public Customer(String name, double discountRate) {
+        this.name = name;
+        this.contract = new CustomerContract(dateToday(), discountRate);
+    }
+
+    public double getDiscountRate() {
+        return this.contract.getDiscountRate();
+    }
+
+    public void setDiscountRate(double discountRate) {
+        this.contract.setDiscountRate(discountRate);
+    }
+
+    public void becomePreferred() {
+        this.setDiscountRate(this.getDiscountRate() + 0.03);
+        // 다른 작업들
+    }
+
+    public double applyDiscount(double amount) {
+        BigDecimal value = BigDecimal.valueOf(amount);
+        return value.subtract(value.multiply(BigDecimal.valueOf(this.getDiscountRate()))).doubleValue();
+    }
+
+    private LocalDate dateToday() {
+        return LocalDate.now();
+    }
+}

refactoring/src/main/java/com/example/refactoring/_08_shotgun_surgery/_27_move_field/CustomerContract.java

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+package com.example.refactoring._08_shotgun_surgery._27_move_field;
+
+import java.time.LocalDate;
+
+public class CustomerContract {
+
+    private LocalDate startDate;
+
+    private double discountRate;
+
+    public CustomerContract(LocalDate startDate, double discountRate) {
+        this.startDate = startDate;
+        this.discountRate = discountRate;
+    }
+
+    public double getDiscountRate() {
+        return discountRate;
+    }
+
+    public void setDiscountRate(double discountRate) {
+        this.discountRate = discountRate;
+    }
+}

refactoring/src/main/java/com/example/refactoring/_08_shotgun_surgery/_27_move_field/_before/Customer.java

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+package com.example.refactoring._08_shotgun_surgery._27_move_field._before;
+
+import java.math.BigDecimal;
+import java.time.LocalDate;
+
+public class Customer {
+
+    private String name;
+
+    private double discountRate;
+
+    private CustomerContract contract;
+
+    public Customer(String name, double discountRate) {
+        this.name = name;
+        this.discountRate = discountRate;
+        this.contract = new CustomerContract(dateToday());
+    }
+
+    public double getDiscountRate() {
+        return discountRate;
+    }
+
+    public void becomePreferred() {
+        this.discountRate += 0.03;
+        // 다른 작업들
+    }
+
+    public double applyDiscount(double amount) {
+        BigDecimal value = BigDecimal.valueOf(amount);
+        return value.subtract(value.multiply(BigDecimal.valueOf(this.discountRate))).doubleValue();
+    }
+
+    private LocalDate dateToday() {
+        return LocalDate.now();
+    }
+}

refactoring/src/main/java/com/example/refactoring/_08_shotgun_surgery/_27_move_field/_before/CustomerContract.java

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+package com.example.refactoring._08_shotgun_surgery._27_move_field._before;
+
+import java.time.LocalDate;
+
+public class CustomerContract {
+
+    private LocalDate startDate;
+
+    public CustomerContract(LocalDate startDate) {
+        this.startDate = startDate;
+    }
+}

refactoring/src/test/java/com/example/refactoring/_08_shotgun_surgery/_27_move_field/CustomerTest.java

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+package com.example.refactoring._08_shotgun_surgery._27_move_field;
+
+import org.junit.jupiter.api.Test;
+
+import static org.junit.jupiter.api.Assertions.*;
+
+class CustomerTest {
+
+    @Test
+    void applyDiscount() {
+        Customer customer = new Customer("kim", 0.5);
+        assertEquals(50, customer.applyDiscount(100));
+
+        customer.becomePreferred();
+        assertEquals(47, customer.applyDiscount(100));
+    }
+
+}