Add corresponding tests

app/src/test/java/ch/nuth/zhaw/exbox/ADS4_2_test.java

@@ -0,0 +1,101 @@
+package ch.nuth.zhaw.exbox;
+
+import org.junit.jupiter.api.Test;
+import org.junit.jupiter.api.BeforeEach;
+
+import java.util.StringTokenizer;
+
+import static org.junit.jupiter.api.Assertions.assertEquals;
+
+public class ADS4_2_test {
+    HilbertServer hlb;
+    Turtle turtle;
+    final double EPS = 1E-1;
+
+    double angle(double x1, double y1, double x2, double y2,
+            double x3, double y3, double x4, double y4) {
+        double ax, ay, bx, by;
+        // https://www.frustfrei-lernen.de/mathematik/schnittwinkel-zweier-geraden.html
+        ax = x2 - x1;
+        ay = y2 - y1;
+        bx = x4 - x3;
+        by = y4 - y3;
+
+        double a = Math.acos(
+                (ax * bx + ay * by)
+                        / (Math.sqrt(ax * ax + ay * ay) * Math.sqrt(bx * bx + by * by)));
+
+        return a / Math.PI * 180;
+    }
+
+    double angle(String line1, String line2) {
+        StringTokenizer tok = new StringTokenizer(line1, " <>=/,\"\n");
+        tok.nextToken(); // line
+        tok.nextToken();
+        double x1 = Double.parseDouble(tok.nextToken());
+        tok.nextToken();
+        double y1 = Double.parseDouble(tok.nextToken());
+        tok.nextToken();
+        double x2 = Double.parseDouble(tok.nextToken());
+        tok.nextToken();
+        double y2 = Double.parseDouble(tok.nextToken());
+        tok = new StringTokenizer(line2, " <>=/,\"\n");
+        tok.nextToken(); // line
+        tok.nextToken();
+        double x3 = Double.parseDouble(tok.nextToken());
+        tok.nextToken();
+        double y3 = Double.parseDouble(tok.nextToken());
+        tok.nextToken();
+        double x4 = Double.parseDouble(tok.nextToken());
+        tok.nextToken();
+        double y4 = Double.parseDouble(tok.nextToken());
+        return angle(x1, y1, x2, y2, x3, y3, x4, y4);
+    }
+
+    @BeforeEach
+    public void setUp() {
+        hlb = new HilbertServer();
+        turtle = new Turtle();
+    }
+
+    private void hilbert(int depth, double dist, double angle) {
+        if (depth >= 0) {
+            turtle.turn(-angle);
+            hilbert(depth - 1, dist, -angle);
+            turtle.move(dist);
+            turtle.turn(angle);
+            hilbert(depth - 1, dist, angle);
+            turtle.move(dist);
+            hilbert(depth - 1, dist, angle);
+            turtle.turn(angle);
+            turtle.move(dist);
+            hilbert(depth - 1, dist, -angle);
+            turtle.turn(-angle);
+        }
+    }
+
+    @Test
+    public void testCountEdges() {
+        turtle.clear();
+        hilbert(3, .4, -90);
+        String[] linesGood = Turtle.instance().getTrace().split("\n");
+        turtle.clear();
+        hlb.execute("3");
+        String[] lines = Turtle.instance().getTrace().split("\n");
+        assertEquals(linesGood.length, lines.length, "Count Edges");
+    }
+
+    @Test
+    public void testAngles() {
+        turtle.clear();
+        hilbert(3, .4, -90);
+        String[] linesGood = Turtle.instance().getTrace().split("\n");
+        turtle.clear();
+        hlb.execute("3");
+        String[] lines = Turtle.instance().getTrace().split("\n");
+
+        for (int i = 0; i < linesGood.length - 1; i++) {
+            assertEquals(angle(linesGood[i], linesGood[i + 1]), angle(lines[i], lines[i + 1]), EPS, "Angle " + i);
+        }
+    }
+}