Added some, lacking but better than nothing, integration tests.

tests/test_cli.rs

@@ -0,0 +1,31 @@
+extern crate assert_cli;
+extern crate hammond;
+
+// Notes:
+// The following tests will use your systems local hammond db.
+// There are no test for failure, cause the behavior have not
+// been defined/though yet.
+
+#[test]
+fn test_update() {
+    assert_cli::Assert::main_binary()
+        .with_args(&["--update"])
+        .unwrap();
+}
+
+#[test]
+fn test_download() {
+    assert_cli::Assert::main_binary()
+        .with_args(&["--download"])
+        .unwrap();
+}
+
+#[test]
+fn test_add() {
+    assert_cli::Assert::main_binary()
+        .with_args(&[
+            "--add",
+            "https://feeds.feedburner.com/InterceptedWithJeremyScahill",
+        ])
+        .unwrap();
+}