1 files changed, 194 insertions, 0 deletions
diff --git a/tests/cast_slice_tests.rs b/tests/cast_slice_tests.rs
new file mode 100644
index 0000000..2838d46
--- /dev/null
+++ b/tests/cast_slice_tests.rs
@@ -0,0 +1,194 @@
+use core::mem::size_of;
+
+use bytemuck::*;
+
+#[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]);
+}
+
+#[test]
+fn test_bytes_of() {
+  assert_eq!(bytes_of(&0xaabbccdd_u32), &0xaabbccdd_u32.to_ne_bytes());
+  assert_eq!(
+    bytes_of_mut(&mut 0xaabbccdd_u32),
+    &mut 0xaabbccdd_u32.to_ne_bytes()
+  );
+  let mut a = 0xaabbccdd_u32;
+  let a_addr = &a as *const _ as usize;
+  // ensure addresses match.
+  assert_eq!(bytes_of(&a).as_ptr() as usize, a_addr);
+  assert_eq!(bytes_of_mut(&mut a).as_ptr() as usize, a_addr);
+}
+
+#[test]
+fn test_try_from_bytes() {
+  let u32s = [0xaabbccdd, 0x11223344_u32];
+  let bytes = bytemuck::cast_slice::<u32, u8>(&u32s);
+  assert_eq!(try_from_bytes::<u32>(&bytes[..4]), Ok(&u32s[0]));
+  assert_eq!(
+    try_from_bytes::<u32>(&bytes[..5]),
+    Err(PodCastError::SizeMismatch)
+  );
+  assert_eq!(
+    try_from_bytes::<u32>(&bytes[..3]),
+    Err(PodCastError::SizeMismatch)
+  );
+  assert_eq!(
+    try_from_bytes::<u32>(&bytes[1..5]),
+    Err(PodCastError::TargetAlignmentGreaterAndInputNotAligned)
+  );
+}
+
+#[test]
+fn test_try_from_bytes_mut() {
+  let mut abcd = 0xaabbccdd;
+  let mut u32s = [abcd, 0x11223344_u32];
+  let bytes = bytemuck::cast_slice_mut::<u32, u8>(&mut u32s);
+  assert_eq!(try_from_bytes_mut::<u32>(&mut bytes[..4]), Ok(&mut abcd));
+  assert_eq!(try_from_bytes_mut::<u32>(&mut bytes[..4]), Ok(&mut abcd));
+  assert_eq!(
+    try_from_bytes_mut::<u32>(&mut bytes[..5]),
+    Err(PodCastError::SizeMismatch)
+  );
+  assert_eq!(
+    try_from_bytes_mut::<u32>(&mut bytes[..3]),
+    Err(PodCastError::SizeMismatch)
+  );
+  assert_eq!(
+    try_from_bytes::<u32>(&bytes[1..5]),
+    Err(PodCastError::TargetAlignmentGreaterAndInputNotAligned)
+  );
+}
+
+#[test]
+fn test_from_bytes() {
+  let abcd = 0xaabbccdd_u32;
+  let aligned_bytes = bytemuck::bytes_of(&abcd);
+  assert_eq!(from_bytes::<u32>(aligned_bytes), &abcd);
+  assert!(core::ptr::eq(from_bytes(aligned_bytes), &abcd));
+}
+
+#[test]
+fn test_from_bytes_mut() {
+  let mut a = 0xaabbccdd_u32;
+  let a_addr = &a as *const _ as usize;
+  let aligned_bytes = bytemuck::bytes_of_mut(&mut a);
+  assert_eq!(*from_bytes_mut::<u32>(aligned_bytes), 0xaabbccdd_u32);
+  assert_eq!(
+    from_bytes_mut::<u32>(aligned_bytes) as *const u32 as usize,
+    a_addr
+  );
+}
+
+// like #[should_panic], but can be a part of another test, instead of requiring
+// it to be it's own test.
+macro_rules! should_panic {
+  ($ex:expr) => {
+    assert!(
+      std::panic::catch_unwind(|| {
+        let _ = $ex;
+      })
+      .is_err(),
+      concat!("should have panicked: `", stringify!($ex), "`")
+    );
+  };
+}
+
+#[test]
+fn test_panics() {
+  should_panic!(cast_slice::<u8, u32>(&[1u8, 2u8]));
+  should_panic!(cast_slice_mut::<u8, u32>(&mut [1u8, 2u8]));
+  should_panic!(from_bytes::<u32>(&[1u8, 2]));
+  should_panic!(from_bytes::<u32>(&[1u8, 2, 3, 4, 5]));
+  should_panic!(from_bytes_mut::<u32>(&mut [1u8, 2]));
+  should_panic!(from_bytes_mut::<u32>(&mut [1u8, 2, 3, 4, 5]));
+  // use cast_slice on some u32s to get some align>=4 bytes, so we can know
+  // we'll give from_bytes unaligned ones.
+  let aligned_bytes = bytemuck::cast_slice::<u32, u8>(&[0, 0]);
+  should_panic!(from_bytes::<u32>(&aligned_bytes[1..5]));
+}