Write test

test/tree_test.dart

@@ -0,0 +1,75 @@
+
+library dlog.example;
+
+import "package:unittest/unittest.dart";
+import "package:dlog/dlog.dart" as DLog;
+
+main() {
+
+  test("Tree flat", (){
+
+    var tree = new DLog.Tree("Tree flat");
+    var output = [
+      'Tree flat',
+      '│ ├ 0',
+      '│ ├ 1',
+      '│ ├ 2',
+      '│ ├ 3',
+      '│ ├ 4',
+      '│ ├ 5',
+      '│ ├ 6',
+      '│ ├ 7',
+      '│ ├ 8',
+      '│ └ 9',
+      ''
+    ];
+
+    tree.openGroup();
+    for (int i = 0; i < 10; i++) {
+      tree.add(i);
+    }
+    tree.closeGroup();
+
+    expect(tree.toString(), output.join(tree.endOfLineUnicode));
+
+  });
+
+  test("Tree 3x3", (){
+
+    var tree = new DLog.Tree("Tree 3x3");
+    var output = [
+      'Tree 3x3\n'
+      '│ ├ 0\n'
+      '│ │ ├ 0x0\n'
+      '│ │ ├ 0x1\n'
+      '│ │ └ 0x2\n'
+      '│ ├ 1\n'
+      '│ │ ├ 1x0\n'
+      '│ │ ├ 1x1\n'
+      '│ │ └ 1x2\n'
+      '│ ├ 2\n'
+      '│ │ ├ 2x0\n'
+      '│ │ ├ 2x1\n'
+      '│ │ └ 2x2\n'
+      ''
+    ];
+
+    tree.openGroup();
+
+    for (int i = 0; i < 3; i++) {
+      tree.add(i);
+      tree.openGroup();
+      for (int j = 0; j < 3; j++) {
+        tree.add("${i}x${j}");
+      }
+      tree.closeGroup();
+    }
+
+    tree.closeGroup();
+
+    // TODO join separator is not working on unknown reason
+    expect(tree.toString(), output.join());
+
+  });
+
+}