Merge pull request #790 from Andlon/compile_error_for_missing_test_features

Fail test compilation if mandatory features are missing

tests/lib.rs

@@ -1,3 +1,9 @@
+#[cfg(any(not(feature = "debug"), not(feature = "compare")))]
+compile_error!(
+    "Please enable the `debug` and `compare` features in order to compile and run the tests.
+     Example: `cargo test --features debug --features compare`"
+);
+
 #[cfg(feature = "abomonation-serialize")]
 extern crate abomonation;
 #[macro_use]