Java में Test Driven Development

public class Main {
	public static void main(String[] args) {
		// Red -> Green -> Refactor
		System.out.println("Write the test before the production code that makes it pass");
	}
}

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import static org.junit.jupiter.api.Assertions.*;
import org.junit.jupiter.api.Test;
public class Main {
	static int add(int a, int b) { return 0; } // not implemented yet -- test should fail
	@Test
	void testAdd() {
		assertEquals(5, add(2, 3)); // fails: proves the test can actually catch a wrong result
	}
	public static void main(String[] args) {
		System.out.println("Red: test written, expected to fail against the stub");
	}
}

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import static org.junit.jupiter.api.Assertions.*;
import org.junit.jupiter.api.Test;
public class Main {
	static int add(int a, int b) { return a + b; } // minimal code to pass, not yet polished
	@Test
	void testAdd() {
		assertEquals(5, add(2, 3));
	}
	public static void main(String[] args) {
		new Main().testAdd();
		System.out.println("Green: test now passes");
	}
}

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import static org.junit.jupiter.api.Assertions.*;
import org.junit.jupiter.api.Test;
public class Main {
	static int add(int... numbers) { // cleaned up to accept any count of numbers
		int sum = 0;
		for (int n : numbers) sum += n;
		return sum;
	}
	@Test
	void testAdd() {
		assertEquals(5, add(2, 3)); // still passes after refactoring
	}
	public static void main(String[] args) {
		new Main().testAdd();
		System.out.println("Refactor: cleaned up, tests still green");
	}
}

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import static org.junit.jupiter.api.Assertions.*;
import org.junit.jupiter.api.Test;
public class Main {
	static double discount(double price, double percent) { return price - (price * percent / 100); }
	@Test
	void testDiscount() {
		assertEquals(90.0, discount(100.0, 10.0)); // background calculation verified before shipping
	}
	public static void main(String[] args) {
		new Main().testDiscount();
		System.out.println("Discount calculation verified via test-first development");
	}
}

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