first lab

build.gradle

@@ -16,4 +16,4 @@ dependencies {
 
 test {
     useJUnitPlatform()
-}
+}

settings.gradle

@@ -1,2 +1 @@
 rootProject.name = 'parallel-programming'
-

src/main/java/ru/lionarius/AreaCalculator.java

@@ -0,0 +1,11 @@
+package ru.lionarius;
+
+public class AreaCalculator {
+
+    public double circle(double radius) {
+        if (radius < 0.0)
+            throw new IllegalArgumentException("radius cannot be negative");
+
+        return Math.PI * radius * radius;
+    }
+}

src/main/java/ru/lionarius/Main.java

@@ -4,4 +4,4 @@ public class Main {
     public static void main(String[] args) {
         System.out.println("Hello world!");
     }
-}
+}

src/test/java/AreaCalculatorTests.java

@@ -0,0 +1,21 @@
+import static org.junit.jupiter.api.Assertions.*;
+
+import org.junit.jupiter.api.Test;
+import ru.lionarius.AreaCalculator;
+
+class AreaCalculatorTests {
+
+    private final AreaCalculator areaCalculator = new AreaCalculator();
+
+    @Test
+    void circleArea() {
+        assertEquals(0.0, this.areaCalculator.circle(0.0));
+        assertEquals(Math.PI, this.areaCalculator.circle(1.0));
+        assertEquals(Math.PI * 4.0, this.areaCalculator.circle(2.0));
+
+        assertThrowsExactly(IllegalArgumentException.class, () -> this.areaCalculator.circle(-1.0));
+
+        assertEquals(Double.POSITIVE_INFINITY, this.areaCalculator.circle(Double.MAX_VALUE));
+        assertEquals(Double.NaN, this.areaCalculator.circle(Double.NaN));
+    }
+}