Fix as_bytes() test for big endian targets

.github/workflows/ci.yml

@@ -96,8 +96,7 @@ jobs:
       # Miri (and wouldn't want to do anyway).
       #
       # TODO(#21): Fix `test_new_error` on i686 and re-enable it here.
-      # TODO(#23): Fix `test_as_bytes_methods` on powerpc and re-enable it here.
-      run: cargo +${{ matrix.channel }} miri test --target ${{ matrix.target }} --features "${{ matrix.features }}" -- --skip ui ${{ contains(matrix.target, 'i686') && '--skip test_new_error' || '' }} ${{ contains(matrix.target, 'powerpc') && '--skip test_as_bytes_methods' || '' }}
+      run: cargo +${{ matrix.channel }} miri test --target ${{ matrix.target }} --features "${{ matrix.features }}" -- --skip ui ${{ contains(matrix.target, 'i686') && '--skip test_new_error' || '' }}
       # Only nightly has a working Miri, so we skip installing on all other
       # toolchains.
       #

src/lib.rs

@@ -2872,31 +2872,49 @@ mod tests {
         }
 
         let mut foo = Foo { a: 1, b: Wrapping(2), c: None };
+
         // Test that we can access the underlying bytes, and that we get the
         // right bytes and the right number of bytes.
-        assert_eq!(foo.as_bytes(), [1, 0, 0, 0, 2, 0, 0, 0, 0, 0, 0, 0]);
+        let expected: Vec<u8> = if cfg!(target_endian = "little") {
+            vec![1, 0, 0, 0, 2, 0, 0, 0, 0, 0, 0, 0]
+        } else {
+            vec![0, 0, 0, 1, 0, 0, 0, 2, 0, 0, 0, 0]
+        };
+        assert_eq!(foo.as_bytes(), expected.as_bytes());
+
         // Test that changes to the underlying byte slices are reflected in the
         // original object.
         foo.as_bytes_mut()[0] = 3;
-        assert_eq!(foo, Foo { a: 3, b: Wrapping(2), c: None });
+        let expected_a = if cfg!(target_endian = "little") { 0x00_00_00_03 } else { 0x03_00_00_01 };
+        assert_eq!(foo, Foo { a: expected_a, b: Wrapping(2), c: None });
 
         // Do the same tests for a slice, which ensures that this logic works
         // for unsized types as well.
         let foo = &mut [
             Foo { a: 1, b: Wrapping(2), c: None },
             Foo { a: 3, b: Wrapping(4), c: NonZeroU32::new(1) },
         ];
-        assert_eq!(
-            foo.as_bytes(),
-            [1, 0, 0, 0, 2, 0, 0, 0, 0, 0, 0, 0, 3, 0, 0, 0, 4, 0, 0, 0, 1, 0, 0, 0]
-        );
+        let expected = if cfg!(target_endian = "little") {
+            vec![1, 0, 0, 0, 2, 0, 0, 0, 0, 0, 0, 0, 3, 0, 0, 0, 4, 0, 0, 0, 1, 0, 0, 0]
+        } else {
+            vec![0, 0, 0, 1, 0, 0, 0, 2, 0, 0, 0, 0, 0, 0, 0, 3, 0, 0, 0, 4, 0, 0, 0, 1]
+        };
+        assert_eq!(foo.as_bytes(), expected);
+
         foo.as_bytes_mut()[8] = 5;
         foo.as_bytes_mut()[16] = 6;
+        let expected_c_1 = NonZeroU32::new(if cfg!(target_endian = "little") {
+            0x00_00_00_05
+        } else {
+            0x05_00_00_00
+        });
+        let expected_b_2 =
+            Wrapping(if cfg!(target_endian = "little") { 0x00_00_00_06 } else { 0x06_00_00_04 });
         assert_eq!(
             foo,
-            &mut [
-                Foo { a: 1, b: Wrapping(2), c: NonZeroU32::new(5) },
-                Foo { a: 3, b: Wrapping(6), c: NonZeroU32::new(1) }
+            &[
+                Foo { a: 1, b: Wrapping(2), c: expected_c_1 },
+                Foo { a: 3, b: expected_b_2, c: NonZeroU32::new(1) },
             ]
         );
     }