Corrected tests and implemented rotation of points.

src/AudioClient.java

@@ -1,5 +1,8 @@
 import com.xtaudio.xt.*;
 
+import java.util.ArrayList;
+import java.util.List;
+
 public class AudioClient {
   public static void main(String[] args) throws Exception {
     int sampleRate = 192000;
@@ -25,4 +28,12 @@ public class AudioClient {
 
     }
   }
+
+  public static List<Line> generatePolygon(int sides, double scale) {
+    List<Line> polygon = new ArrayList<>();
+
+    Point start = new Point(scale, scale);
+
+    return null;
+  }
 }

src/Line.java

@@ -17,19 +17,7 @@ public class Line {
   }
 
   public Line rotate(double theta) {
-    double x1 = getX1();
-    double y1 = getY1();
-    double x2 = getX2();
-    double y2 = getY2();
-
-    Line line = new Line(x1, y1, x2, y2);
-
-    line.setX1(x1 * Math.cos(theta) - y1 * Math.sin(theta));
-    line.setY1(x1 * Math.sin(theta) + y1 * Math.cos(theta));
-    line.setX2(x2 * Math.cos(theta) - y2 * Math.sin(theta));
-    line.setY2(x2 * Math.sin(theta) + y2 * Math.cos(theta));
-
-    return line;
+    return new Line(getA().rotate(theta), getB().rotate(theta));
   }
 
   public Point getA() {

src/Point.java

@@ -38,6 +38,18 @@ public class Point {
     }
   }
 
+  public Point rotate(double theta) {
+    double oldX = getX();
+    double oldY = getY();
+
+    Point point = new Point(oldX, oldY);
+
+    point.setX(oldX * Math.cos(theta) - oldY * Math.sin(theta));
+    point.setY(oldX * Math.sin(theta) + oldY * Math.cos(theta));
+
+    return point;
+  }
+
   private boolean approxEquals(double m, double n) {
     return Math.abs(m - n) < EPSILON;
   }

test/TestSuite.java

@@ -7,24 +7,16 @@ public class TestSuite {
   public void lineRotationTest1() {
     Line line = new Line(-0.5, 0.5, 0.5, 0.5);
 
-    line.rotate(Math.PI / 2);
-    assertEquals(new Line(-0.5, -0.5, -0.5, 0.5), line);
-
-    line.rotate(Math.PI / 2);
-    assertEquals(new Line(0.5, -0.5, -0.5, -0.5), line);
-
-    line.rotate(Math.PI / 2);
-    assertEquals(new Line(0.5, 0.5, 0.5, -0.5), line);
-
-    line.rotate(Math.PI / 2);
-    assertEquals(new Line(-0.5, 0.5, 0.5, 0.5), line);
+    assertEquals(new Line(-0.5, -0.5, -0.5, 0.5), line.rotate(Math.PI / 2));
+    assertEquals(new Line(0.5, -0.5, -0.5, -0.5), line.rotate(Math.PI));
+    assertEquals(new Line(0.5, 0.5, 0.5, -0.5), line.rotate(3 * Math.PI / 2));
+    assertEquals(new Line(-0.5, 0.5, 0.5, 0.5), line.rotate(2 * Math.PI));
   }
 
   @Test
   public void lineRotationTest2() {
     Line line = new Line(-0.5, -0.5, -0.25, 0.5);
 
-    line.rotate(Math.PI / 2);
-    assertEquals(new Line(0.5, -0.5, -0.5, -0.25), line);
+    assertEquals(new Line(0.5, -0.5, -0.5, -0.25), line.rotate(Math.PI / 2));
   }
 }