Create cast_slice_tests.rs

tests/cast_slice_tests.rs

@@ -0,0 +1,89 @@
+use core::mem::size_of;
+
+use lokacore::*;
+
+#[test]
+fn test_try_cast_slice() {
+  // some align4 data
+  let u32_slice: &[u32] = &[4, 5, 6];
+  // the same data as align1
+  let the_bytes: &[u8] = try_cast_slice(u32_slice).unwrap();
+
+  assert_eq!(
+    u32_slice.as_ptr() as *const u32 as usize,
+    the_bytes.as_ptr() as *const u8 as usize
+  );
+  assert_eq!(
+    u32_slice.len() * size_of::<u32>(),
+    the_bytes.len() * size_of::<u8>()
+  );
+
+  // by taking one byte off the front, we're definitely mis-aligned for u32.
+  let mis_aligned_bytes = &the_bytes[1..];
+  assert_eq!(
+    try_cast_slice::<u8, u32>(mis_aligned_bytes),
+    Err(PodCastError::TargetAlignmentGreaterAndInputNotAligned)
+  );
+
+  // by taking one byte off the end, we're aligned but would have slop bytes for u32
+  let the_bytes_len_minus1 = the_bytes.len() - 1;
+  let slop_bytes = &the_bytes[..the_bytes_len_minus1];
+  assert_eq!(
+    try_cast_slice::<u8, u32>(slop_bytes),
+    Err(PodCastError::OutputSliceWouldHaveSlop)
+  );
+
+  // if we don't mess with it we can up-alignment cast
+  try_cast_slice::<u8, u32>(the_bytes).unwrap();
+}
+
+#[test]
+fn test_try_cast_slice_mut() {
+  // some align4 data
+  let u32_slice: &mut [u32] = &mut [4, 5, 6];
+  let u32_len = u32_slice.len();
+  let u32_ptr = u32_slice.as_ptr();
+  // the same data as align1
+  let the_bytes: &mut [u8] = try_cast_slice_mut(u32_slice).unwrap();
+  let the_bytes_len = the_bytes.len();
+  let the_bytes_ptr = the_bytes.as_ptr();
+
+  assert_eq!(
+    u32_ptr as *const u32 as usize,
+    the_bytes_ptr as *const u8 as usize
+  );
+  assert_eq!(u32_len * size_of::<u32>(), the_bytes_len * size_of::<u8>());
+
+  // by taking one byte off the front, we're definitely mis-aligned for u32.
+  let mis_aligned_bytes = &mut the_bytes[1..];
+  assert_eq!(
+    try_cast_slice_mut::<u8, u32>(mis_aligned_bytes),
+    Err(PodCastError::TargetAlignmentGreaterAndInputNotAligned)
+  );
+
+  // by taking one byte off the end, we're aligned but would have slop bytes for u32
+  let the_bytes_len_minus1 = the_bytes.len() - 1;
+  let slop_bytes = &mut the_bytes[..the_bytes_len_minus1];
+  assert_eq!(
+    try_cast_slice_mut::<u8, u32>(slop_bytes),
+    Err(PodCastError::OutputSliceWouldHaveSlop)
+  );
+
+  // if we don't mess with it we can up-alignment cast
+  try_cast_slice_mut::<u8, u32>(the_bytes).unwrap();
+}
+
+#[test]
+fn test_types() {
+  let _: i32 = cast(1.0_f32);
+  let _: &mut i32 = cast_mut(&mut 1.0_f32);
+  let _: &i32 = cast_ref(&1.0_f32);
+  let _: &[i32] = cast_slice(&[1.0_f32]);
+  let _: &mut [i32] = cast_slice_mut(&mut [1.0_f32]);
+  //
+  let _: Result<i32, PodCastError> = try_cast(1.0_f32);
+  let _: Result<&mut i32, PodCastError> = try_cast_mut(&mut 1.0_f32);
+  let _: Result<&i32, PodCastError> = try_cast_ref(&1.0_f32);
+  let _: Result<&[i32], PodCastError> = try_cast_slice(&[1.0_f32]);
+  let _: Result<&mut [i32], PodCastError> = try_cast_slice_mut(&mut [1.0_f32]);
+}