WIP: add tiny tests + THERE'S A BUG

Only on bit of SparseBitmask is true.
But SparseBitmask.region().cursor() seems to have two elements?

src/test/java/net/imglib2/roi/sparse/GrowableTreeTest.java

@@ -0,0 +1,14 @@
+package net.imglib2.roi.sparse;
+
+import org.junit.Test;
+
+import static org.junit.Assert.assertEquals;
+
+public class GrowableTreeTest
+{
+	@Test
+	public void testCreate() {
+		GrowableTree tree = new GrowableTree( new int[] { 8, 8, 8 } );
+		assertEquals(0,  tree.height());
+	}
+}

src/test/java/net/imglib2/roi/sparse/SparseBitmaskTest.java

@@ -0,0 +1,50 @@
+package net.imglib2.roi.sparse;
+
+import net.imglib2.Cursor;
+import net.imglib2.RandomAccess;
+import net.imglib2.roi.IterableRegion;
+import net.imglib2.type.logic.NativeBoolType;
+import net.imglib2.util.Localizables;
+import org.junit.Test;
+
+import static junit.framework.TestCase.assertTrue;
+import static org.junit.Assert.assertArrayEquals;
+import static org.junit.Assert.assertEquals;
+import static org.junit.Assert.assertFalse;
+
+public class SparseBitmaskTest
+{
+	@Test
+	public void testCreate() {
+		new SparseBitmask( 3 );
+	}
+
+	@Test
+	public void testRandomAccess() {
+		SparseBitmask bitmask = new SparseBitmask( 3 );
+		RandomAccess< NativeBoolType > ra = bitmask.randomAccess();
+		ra.get().set( true );
+		assertTrue( ra.get().get() );
+		ra.get().set( false );
+		assertFalse( ra.get().get() );
+	}
+
+
+	@Test
+	public void testRegion() {
+		SparseBitmask bitmask = new SparseBitmask( 3 );
+		RandomAccess< NativeBoolType > ra = bitmask.randomAccess();
+		final long[] position = { 1, 2, 3 };
+		ra.setPosition( position );
+		ra.get().set( true );
+		final IterableRegion< NativeBoolType > region = bitmask.region();
+		Cursor< Void > cursor = region.cursor();
+		assertEquals(1, region.size());
+		assertTrue( cursor.hasNext() );
+		cursor.next();
+		assertArrayEquals( position, Localizables.asLongArray( cursor ) );
+		assertFalse( cursor.hasNext() );
+	}
+
+
+}