Merge pull request #61 from rubberduck203/tests

Add example of writing tests that run on host machine

Author: korken89

examples/test_on_host.rs

@@ -0,0 +1,57 @@
+//! Conditionally compiling tests with std and our executable with no_std.
+//!
+//! Rust's built in unit testing framework requires the standard library,
+//! but we need to build our final executable with no_std.
+//! The testing framework also generates a `main` method, so we need to only use the `#[entry]`
+//! annotation when building our final image.
+//! For more information on why this example works, see this excellent blog post.
+//! https://os.phil-opp.com/unit-testing/
+//!
+//! Running this example:
+//!
+//! Ensure there are no targets specified under `[build]` in `.cargo/config`
+//! In order to make this work, we lose the convenience of having a default target that isn't the
+//! host.
+//!
+//! cargo build --example test_on_host --target thumbv7m-none-eabi
+//! cargo test --example test_on_host
+
+#![cfg_attr(test, allow(unused_imports))]
+
+#![cfg_attr(not(test), no_std)]
+#![cfg_attr(not(test), no_main)]
+
+// pick a panicking behavior
+#[cfg(not(test))]
+extern crate panic_halt; // you can put a breakpoint on `rust_begin_unwind` to catch panics
+// extern crate panic_abort; // requires nightly
+// extern crate panic_itm; // logs messages over ITM; requires ITM support
+// extern crate panic_semihosting; // logs messages to the host stderr; requires a debugger
+
+use cortex_m::asm;
+use cortex_m_rt::entry;
+
+#[cfg(not(test))]
+#[entry]
+fn main() -> ! {
+    asm::nop(); // To not have main optimize to abort in release mode, remove when you add code
+
+    loop {
+        // your code goes here
+    }
+}
+
+fn add(a: i32, b: i32) -> i32 {
+    a + b
+}
+
+#[cfg(test)]
+mod test {
+  use super::*;
+
+  #[test]
+  fn foo() {
+    println!("tests work!");
+    assert!(2 == add(1,1));
+  }
+}