Test driven development demo

src/main/java/com/javafanatics/ActivityCalculator.java

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+package com.javafanatics;
+
+public class ActivityCalculator {
+
+    private static final int WORKOUT_DURATION_MIN = 45;
+
+    public static String rateActivityLevel(int weeklyCardioMinutes, int weeklyWorkoutSessions) {
+
+        if (weeklyCardioMinutes <0 || weeklyWorkoutSessions <0) {
+            throw new RuntimeException("Input below 20");
+        }
+
+        int  totalMinutes  = weeklyCardioMinutes + weeklyWorkoutSessions * WORKOUT_DURATION_MIN;
+        double avgDailyActivityMinutes = totalMinutes / 7.0;
+
+        if (avgDailyActivityMinutes < 20) {
+            return "bad";
+        } else if (avgDailyActivityMinutes < 40) {
+            return "average";
+        }
+        return "good";
+    }
+}

src/test/java/com/javafanatics/ActivityCalculatorTest.java

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+package com.javafanatics;
+
+import org.junit.jupiter.api.Test;
+import org.junit.jupiter.api.function.Executable;
+
+
+import static org.junit.jupiter.api.Assertions.*;
+
+class ActivityCalculatorTest {
+
+    @Test
+    void should_ReturnBad_When_AgeBelow20(){
+        //given
+        int weeklyCardioMinutes = 40;
+        int weeklyWorkouts = 1;
+
+        //when
+        String actual = ActivityCalculator.rateActivityLevel(weeklyCardioMinutes, weeklyWorkouts);
+
+        //then
+        assertEquals("bad", actual);
+    }
+
+    @Test
+    void should_ReturnAverage_When_AgeBetween20and40(){
+        //given
+        int weeklyCardioMinutes = 40;
+        int weeklyWorkouts = 3;
+
+        //when
+        String actual = ActivityCalculator.rateActivityLevel(weeklyCardioMinutes, weeklyWorkouts);
+
+        //then
+        assertEquals("average", actual);
+
+    }
+
+    @Test
+    void should_ReturnGood_When_AgeAbove40(){
+        //given
+        int weeklyCardioMinutes = 40;
+        int weeklyWorkouts = 7;
+
+        //when
+        String actual = ActivityCalculator.rateActivityLevel(weeklyCardioMinutes, weeklyWorkouts);
+
+        //then
+        assertEquals("good", actual);
+
+    }
+
+    @Test
+    void should_ThrowException_When_InputBelowZero(){
+        //given
+        int weeklyCardioMinutes = -40;
+        int weeklyWorkouts = 7;
+
+        //when
+        Executable executable = () -> ActivityCalculator.rateActivityLevel(weeklyCardioMinutes, weeklyWorkouts);
+
+
+        //then
+        assertThrows(RuntimeException.class, executable);
+
+    }
+
+
+
+
+}