Update error tests

.github/workflows/main.yml

@@ -27,8 +27,8 @@ jobs:
       - name: Build ${{ matrix.lua }} vendored
         run: |
           cargo build --features "${{ matrix.lua }},vendored"
-          cargo build --features "${{ matrix.lua }},vendored,async,serialize,macros"
-          cargo build --features "${{ matrix.lua }},vendored,async,serialize,macros,send"
+          cargo build --features "${{ matrix.lua }},vendored,async,serialize,macros,anyhow"
+          cargo build --features "${{ matrix.lua }},vendored,async,serialize,macros,anyhow,send"
         shell: bash
       - name: Build ${{ matrix.lua }} pkg-config
         if: ${{ matrix.os == 'ubuntu-latest' }}
@@ -123,8 +123,8 @@ jobs:
       - name: Run ${{ matrix.lua }} tests
         run: |
           cargo test --features "${{ matrix.lua }},vendored"
-          cargo test --features "${{ matrix.lua }},vendored,async,serialize,macros"
-          cargo test --features "${{ matrix.lua }},vendored,async,serialize,macros,send"
+          cargo test --features "${{ matrix.lua }},vendored,async,serialize,macros,anyhow"
+          cargo test --features "${{ matrix.lua }},vendored,async,serialize,macros,anyhow,send"
         shell: bash
       - name: Run compile tests (macos lua54)
         if: ${{ matrix.os == 'macos-latest' && matrix.lua == 'lua54' }}
@@ -281,4 +281,4 @@ jobs:
       - uses: giraffate/clippy-action@v1
         with:
           reporter: 'github-pr-review'
-          clippy_flags: --features "${{ matrix.lua }},vendored,async,send,serialize,macros"
+          clippy_flags: --features "${{ matrix.lua }},vendored,async,send,serialize,macros,anyhow"

src/error.rs

@@ -309,7 +309,7 @@ impl fmt::Display for Error {
             Error::DeserializeError(err) => {
                 write!(fmt, "deserialize error: {err}")
             },
-            Error::ExternalError(err) => write!(fmt, "{err}"),
+            Error::ExternalError(err) => err.fmt(fmt),
             Error::WithContext { context, cause } => {
                 writeln!(fmt, "{context}")?;
                 write!(fmt, "{cause}")
@@ -328,10 +328,7 @@ impl StdError for Error {
             // returns nothing.
             Error::CallbackError { .. } => None,
             Error::ExternalError(err) => err.source(),
-            Error::WithContext { cause, .. } => match cause.as_ref() {
-                Error::ExternalError(err) => err.source(),
-                _ => None,
-            },
+            Error::WithContext { cause, .. } => Self::source(&cause),
             _ => None,
         }
     }
@@ -357,10 +354,7 @@ impl Error {
     {
         match self {
             Error::ExternalError(err) => err.downcast_ref(),
-            Error::WithContext { cause, .. } => match cause.as_ref() {
-                Error::ExternalError(err) => err.downcast_ref(),
-                _ => None,
-            },
+            Error::WithContext { cause, .. } => Self::downcast_ref(&cause),
             _ => None,
         }
     }
@@ -373,6 +367,16 @@ impl Error {
         }
     }
 
+    /// Returns the parent of this error.
+    #[doc(hidden)]
+    pub fn parent(&self) -> Option<&Error> {
+        match self {
+            Error::CallbackError { cause, .. } => Some(cause.as_ref()),
+            Error::WithContext { cause, .. } => Some(cause.as_ref()),
+            _ => None,
+        }
+    }
+
     pub(crate) fn bad_self_argument(to: &str, cause: Error) -> Self {
         Error::BadArgument {
             to: Some(to.to_string()),

tarpaulin.toml

@@ -1,5 +1,5 @@
 [lua54_coverage]
-features = "lua54,vendored,async,send,serialize,macros"
+features = "lua54,vendored,async,send,serialize,macros,anyhow"
 
 [lua54_with_memory_limit_coverage]
 features = "lua54,vendored,async,send,serialize,macros"

tests/error.rs

@@ -1,4 +1,5 @@
-use std::io;
+use std::error::Error as _;
+use std::{fmt, io};
 
 use mlua::{Error, ErrorContext, Lua, Result};
 
@@ -27,7 +28,6 @@ fn test_error_context() -> Result<()> {
         .load("local _, err = pcall(func2); return tostring(err)")
         .eval::<String>()?;
     assert!(msg2.contains("failed to find global"));
-    println!("{msg2}");
     assert!(msg2.contains("error converting Lua nil to String"));
 
     // Rewrite context message and test `downcast_ref`
@@ -36,13 +36,12 @@ fn test_error_context() -> Result<()> {
             .context("some context")
             .context("some new context")
     })?;
-    let res = func3.call::<()>(()).err().unwrap();
-    let Error::CallbackError { cause, .. } = &res else {
-        unreachable!()
-    };
-    assert!(!res.to_string().contains("some context"));
-    assert!(res.to_string().contains("some new context"));
-    assert!(cause.downcast_ref::<io::Error>().is_some());
+    let err = func3.call::<()>(()).unwrap_err();
+    let err = err.parent().unwrap();
+    assert!(!err.to_string().contains("some context"));
+    assert!(err.to_string().contains("some new context"));
+    assert!(err.downcast_ref::<io::Error>().is_some());
+    assert!(err.downcast_ref::<fmt::Error>().is_none());
 
     Ok(())
 }
@@ -59,7 +58,7 @@ fn test_error_chain() -> Result<()> {
         let err = Error::external(io::Error::new(io::ErrorKind::Other, "other")).context("io error");
         Err::<(), _>(err)
     })?;
-    let err = func.call::<()>(()).err().unwrap();
+    let err = func.call::<()>(()).unwrap_err();
     assert_eq!(err.chain().count(), 3);
     for (i, err) in err.chain().enumerate() {
         match i {
@@ -70,6 +69,11 @@ fn test_error_chain() -> Result<()> {
         }
     }
 
+    let err = err.parent().unwrap();
+    assert!(err.source().is_none()); // The source is included to the `Display` output
+    assert!(err.to_string().contains("io error"));
+    assert!(err.to_string().contains("other"));
+
     Ok(())
 }