Added some tests for the IOUtil class

src/test/java/tech/bitgoblin/io/IOUtilsTest.java

@@ -0,0 +1,28 @@
+package tech.bitgoblin.io;
+
+import static org.junit.Assert.assertTrue;
+
+import org.junit.Test;
+
+import java.io.File;
+
+public class IOUtilsTest {
+
+  @Test
+  public void shouldCreateDirectory() {
+    IOUtils.createDirectory("test-temp.txt");
+    assertTrue(new File("test-temp.txt").exists());
+  }
+
+  @Test
+  public void shouldExpandTilda() {
+    String homeExpanded = IOUtils.resolveTilda("~");
+    assertTrue(!homeExpanded.equals("~"));
+  }
+
+  @Test(expected=UnsupportedOperationException.class)
+  public void shouldFailExpandExplicitTilda() {
+    IOUtils.resolveTilda("~test");
+  }
+
+}