Add a feature_check workspace crate to test feature macro hygiene.

New `feature_check` crate is a non-default member of the workspace and
verifies that the `storage_types!` macro expands properly based on `uom`'s
features and not features in the calling crate. Part of #61.

.appveyor.yml

@@ -55,7 +55,7 @@ install:
 build: false
 test_script:
   - cargo build --verbose --all-features
-  - cargo test --verbose --features serde
+  - cargo test --all --verbose --features serde
 
 notifications:
     - provider: Email

.travis.yml

@@ -31,7 +31,7 @@ before_script: |
 
 script: |
   cargo build --verbose --all-features &&
-  (test "$TRAVIS_RUST_VERSION" == "1.20.0" || cargo test --verbose --features serde)
+  (test "$TRAVIS_RUST_VERSION" == "1.20.0" || cargo test --all --verbose --features serde)
 
 after_success: |
   test "$TRAVIS_RUST_VERSION" != "stable" || cargo coveralls

Cargo.toml

@@ -20,6 +20,9 @@ travis-ci = { repository = "iliekturtles/uom" }
 coveralls = { repository = "iliekturtles/uom" }
 maintenance = { status = "actively-developed" }
 
+[workspace]
+members = ["tests/feature_check"]
+
 [dependencies]
 num = "0.1"
 serde = { version = "1.0", optional = true, default-features = false }

tests/feature_check/Cargo.toml

@@ -0,0 +1,6 @@
+[package]
+name = "feature_check"
+version = "0.1.0"
+
+[dependencies]
+uom = { path = "../.." }

tests/feature_check/src/lib.rs

@@ -0,0 +1,37 @@
+//! Validate that the feature_check crate has no `f32` feature and `storage_types!` still generates
+//! code for the `f32` type.
+//!
+//! ```
+//! #[macro_use]
+//! extern crate uom;
+//!
+//! #[cfg(feature = "f32")]
+//! compile_error!("Unexpected feature `f32` in feature_check test crate.");
+//!
+//! storage_types! {
+//!     types: i32, f32;
+//!
+//!     pub fn do_work(v: V) {}
+//! }
+//!
+//! fn main() {
+//!     ::f32::do_work(1.0);
+//! }
+//! ```
+//!
+//! Validate that `storage_types!` does not generate code for the `i32` type.
+//!
+//! ```rust,compile_fail
+//! #[macro_use]
+//! extern crate uom;
+//!
+//! storage_types! {
+//!     types: i32, f32;
+//!
+//!     pub fn do_work(v: V) {}
+//! }
+//!
+//! fn main() {
+//!     ::i32::do_work(1.0);
+//! }
+//! ```