support std::error::Error

included is mandataing a `description` method on `DecodeError`
implementors - already approximately required by the Debug and Display
anyway.

also include a StandardPartialDecoderError for incomplete decoders to
use. i expect that one of the last steps of a decoder's 1.0 release will
be to move away from this.

1 files changed, 55 insertions, 2 deletions

diff --git a/tests/lib.rs b/tests/lib.rs
index 15477f7..8e097de 100644
--- a/tests/lib.rs
+++ b/tests/lib.rs
@@ -1,5 +1,3 @@
-#![no_std]
-
 use yaxpeax_arch::AddressBase;
 
 #[test]
@@ -10,3 +8,58 @@ fn test_u16() {
         }
     }
 }
+
+#[test]
+fn error_can_bail() {
+    use yaxpeax_arch::{Arch, AddressDiff, Decoder, Reader, LengthedInstruction, Instruction, StandardDecodeError, U8Reader};
+    struct TestIsa {}
+    #[derive(Debug, Default)]
+    struct TestInst {}
+    impl Arch for TestIsa {
+        type Word = u8;
+        type Address = u64;
+        type Instruction = TestInst;
+        type Decoder = TestIsaDecoder;
+        type DecodeError = StandardDecodeError;
+        type Operand = ();
+    }
+
+    impl Instruction for TestInst {
+        fn well_defined(&self) -> bool { true }
+    }
+
+    impl LengthedInstruction for TestInst {
+        type Unit = AddressDiff<u64>;
+        fn len(&self) -> Self::Unit { AddressDiff::from_const(1) }
+        fn min_size() -> Self::Unit { AddressDiff::from_const(1) }
+    }
+
+    struct TestIsaDecoder {}
+
+    impl Default for TestIsaDecoder {
+        fn default() -> Self {
+            TestIsaDecoder {}
+        }
+    }
+
+    impl Decoder<TestIsa> for TestIsaDecoder {
+        fn decode_into<T: Reader<u64, u8>>(&self, _inst: &mut TestInst, _words: &mut T) -> Result<(), StandardDecodeError> {
+
+            Err(StandardDecodeError::ExhaustedInput)
+        }
+    }
+
+    #[derive(Debug, PartialEq, thiserror::Error)]
+    pub enum Error {
+        #[error("decode error")]
+        TestDecode(#[from] StandardDecodeError),
+    }
+
+    fn exercise_eq() -> Result<(), Error> {
+        let mut reader = U8Reader::new(&[]);
+        TestIsaDecoder::default().decode(&mut reader)?;
+        Ok(())
+    }
+
+    assert_eq!(exercise_eq(), Err(Error::TestDecode(StandardDecodeError::ExhaustedInput)));
+}