first pass at splitting out a test, making ctx/errno reusable

tests/trivial.rs

@@ -0,0 +1,61 @@
+use proptest::prelude::*;
+use std::convert::TryFrom;
+use wiggle_runtime::{
+    GuestArray, GuestError, GuestErrorType, GuestPtr, GuestPtrMut, GuestRef, GuestRefMut,
+};
+use wiggle_test::{HostMemory, MemArea};
+
+mod ctx;
+use ctx::WasiCtx;
+
+wiggle_generate::from_witx!({
+    witx: ["tests/trivial.witx"],
+    ctx: WasiCtx,
+});
+
+impl_errno!(types::Errno);
+
+impl trivial::Trivial for WasiCtx {
+    fn int_float_args(&mut self, an_int: u32, an_float: f32) -> Result<(), types::Errno> {
+        println!("INT FLOAT ARGS: {} {}", an_int, an_float);
+        Ok(())
+    }
+}
+
+// There's nothing meaningful to test here - this just demonstrates the test machinery
+
+#[derive(Debug)]
+struct IntFloatExercise {
+    pub an_int: u32,
+    pub an_float: f32,
+}
+
+impl IntFloatExercise {
+    pub fn test(&self) {
+        let mut ctx = WasiCtx::new();
+        let mut host_memory = HostMemory::new();
+        let mut guest_memory = host_memory.guest_memory();
+
+        let e = trivial::int_float_args(
+            &mut ctx,
+            &mut guest_memory,
+            self.an_int as i32,
+            self.an_float,
+        );
+
+        assert_eq!(e, types::Errno::Ok.into(), "int_float_args error");
+    }
+
+    pub fn strat() -> BoxedStrategy<Self> {
+        (prop::num::u32::ANY, prop::num::f32::ANY)
+            .prop_map(|(an_int, an_float)| IntFloatExercise { an_int, an_float })
+            .boxed()
+    }
+}
+
+proptest! {
+    #[test]
+    fn int_float_exercise(e in IntFloatExercise::strat()) {
+        e.test()
+    }
+}