Run cargo test in Travis-CI

Author: Martin Larralde

.travis.yml

@@ -9,5 +9,7 @@ before_install:
   - git submodule update --init --recursive
 
 script:
-  - cargo build --verbose
+  # build and test the crate
+  - cargo test --verbose
+  # build the example
   - cargo build --verbose --manifest-path=examples/xmp-sys/Cargo.toml