add initial cursor movement support

test/src/test_Buffer.cc

@@ -27,5 +27,17 @@ TEST(BufferTest, allows_navigating_using_cursors)
     Buffer b;
     ASSERT_TRUE(b.load_from_file("test/files/line_endings/lf_format.txt"));
     std::shared_ptr<PieceTable::Cursor> cursor = b.piece_table->add_cursor();
-    EXPECT_EQ((uint32_t)'H', **cursor);
+    ASSERT_EQ((uint32_t)'H', **cursor);
+    cursor->go_up();
+    ASSERT_EQ((uint32_t)'H', **cursor);
+    cursor->go_right();
+    ASSERT_EQ((uint32_t)'e', **cursor);
+    cursor->go_down();
+    ASSERT_EQ((uint32_t)'h', **cursor);
+    cursor->go_left();
+    ASSERT_EQ((uint32_t)'T', **cursor);
+    cursor->go_left();
+    ASSERT_EQ((uint32_t)'T', **cursor);
+    cursor->go_down();
+    ASSERT_EQ((uint32_t)'T', **cursor);
 }