Happy End

src/InsuranceCalculator.java

@@ -1,14 +1,20 @@
 public class InsuranceCalculator {
 
+    private InsuranceStrategy strategy;
+
     public double calculateInsurance(double income) {
         if (income <= 10000) {
-            return income*0.365;
+            strategy = new InsuranceStrategyVeryLowIncome();
+            return strategy.calculate(income);
         } else if (income <= 30000) {
-            return (income-10000)*0.2+35600;
+            strategy = new InsuranceStrategyLowIncome();
+            return strategy.calculate(income);
         } else if (income <= 60000) {
-            return (income-30000)*0.1+76500;
+            strategy = new InsuranceStrategyMedIncome();
+            return strategy.calculate(income);
         } else {
-            return (income-60000)*0.02+105600;
+            strategy = new InsuranceStrategyHighIncome();
+            return strategy.calculate(income);
         }
     }
 

src/InsuranceStrategy.java

@@ -0,0 +1,11 @@
+public abstract class InsuranceStrategy {
+    double calculate(double income) {
+        return (income - getAdjustment()) * getWeight() + getConstant();
+    }
+
+    public abstract int getConstant();
+
+    public abstract double getWeight();
+
+    public abstract int getAdjustment();
+}

src/InsuranceStrategyHighIncome.java

@@ -0,0 +1,20 @@
+public class InsuranceStrategyHighIncome extends InsuranceStrategy {
+    public InsuranceStrategyHighIncome() {
+
+    }
+
+    @Override
+    public int getConstant() {
+        return 105600;
+    }
+
+    @Override
+    public double getWeight() {
+        return 0.02;
+    }
+
+    @Override
+    public int getAdjustment() {
+        return 60000;
+    }
+}

src/InsuranceStrategyLowIncome.java

@@ -0,0 +1,16 @@
+public class InsuranceStrategyLowIncome extends InsuranceStrategy {
+    @Override
+    public int getConstant() {
+        return 35600;
+    }
+
+    @Override
+    public double getWeight() {
+        return 0.2;
+    }
+
+    @Override
+    public int getAdjustment() {
+        return 10000;
+    }
+}

src/InsuranceStrategyMedIncome.java

@@ -0,0 +1,16 @@
+public class InsuranceStrategyMedIncome extends InsuranceStrategy {
+    @Override
+    public int getConstant() {
+        return 76500;
+    }
+
+    @Override
+    public double getWeight() {
+        return 0.1;
+    }
+
+    @Override
+    public int getAdjustment() {
+        return 30000;
+    }
+}

src/InsuranceStrategyVeryLowIncome.java

@@ -0,0 +1,16 @@
+public class InsuranceStrategyVeryLowIncome extends InsuranceStrategy {
+    @Override
+    public int getConstant() {
+        return 0;
+    }
+
+    @Override
+    public double getWeight() {
+        return 0.365;
+    }
+
+    @Override
+    public int getAdjustment() {
+        return 0;
+    }
+}

test/InsuranceCalculatorTest.java

@@ -0,0 +1,27 @@
+import org.junit.jupiter.api.Test;
+
+import static org.junit.jupiter.api.Assertions.*;
+
+class InsuranceCalculatorTest {
+
+    @Test
+    public void CalculateVeryLowIncome() {
+        assertEquals(730, calculateInsurance(2000));
+    }
+    @Test
+    public void CalculateLowIncome() {
+        assertEquals(39600, calculateInsurance(30000));
+    }
+    @Test
+    public void CalculateMedIncome() {
+        assertEquals(79500, calculateInsurance(60000));
+    }
+
+    @Test
+    public void CalculateHighIncome() {
+        assertEquals(106200, calculateInsurance(90000));
+    }
+    private double calculateInsurance(double income) {
+        return new InsuranceCalculator().calculateInsurance(income);
+    }
+}