First pass of using custom test runner

It works!

ctru-rs/src/lib.rs

@@ -1,5 +1,8 @@
 #![crate_type = "rlib"]
 #![crate_name = "ctru"]
+#![feature(test)]
+#![feature(custom_test_frameworks)]
+#![test_runner(test_runner::test_runner)]
 
 /// Call this somewhere to force Rust to link some required crates
 /// This is also a setup for some crate integration only available at runtime
@@ -61,6 +64,9 @@ cfg_if::cfg_if! {
     }
 }
 
+#[cfg(test)]
+mod test_runner;
+
 pub use crate::error::{Error, Result};
 
 pub use crate::gfx::Gfx;

ctru-rs/src/test_runner.rs

@@ -0,0 +1,46 @@
+//! Custom test runner for building/running unit tests on the 3DS.
+
+extern crate test;
+
+use test::TestFn;
+
+use crate::console::Console;
+use crate::gfx::Gfx;
+use crate::services::hid::{Hid, KeyPad};
+
+/// A custom runner to be used with `#[test_runner]`. This simple implementation
+/// runs all tests in series, "failing" on the first one to panic (really, the
+/// panic is just treated the same as any normal application panic).
+pub(crate) fn test_runner(test_cases: &[&test::TestDescAndFn]) {
+    crate::init();
+
+    let gfx = Gfx::default();
+    let hid = Hid::init().expect("Couldn't obtain HID controller");
+    let _console = Console::init(gfx.top_screen.borrow_mut());
+
+    // TODO: may want to use some more features of standard testing framework,
+    // like output capture, filtering, panic handling, etc.
+    // For now this is works without too much setup.
+    for test_info in test_cases {
+        if let TestFn::StaticTestFn(testfn) = test_info.testfn {
+            println!("Running test {}", test_info.desc.name);
+            testfn();
+        } else {
+            println!(
+                "unsupported test type for {}: {:?}",
+                test_info.desc.name, test_info.testfn
+            );
+        }
+    }
+
+    println!("All tests passed! Press START to exit.");
+
+    // TODO: do we need apt.main_loop() here?
+    loop {
+        hid.scan_input();
+
+        if hid.keys_down().contains(KeyPad::KEY_START) {
+            break;
+        }
+    }
+}