use miette::Diagnostic; #[derive(Debug, miette::Diagnostic, thiserror::Error)] #[error("AnErr")] struct AnErr; #[derive(Debug, miette::Diagnostic, thiserror::Error)] #[error("TestError")] struct TestError { #[diagnostic_source] asdf_inner_foo: AnErr, } #[test] fn test_diagnostic_source() { let error = TestError { asdf_inner_foo: AnErr, }; assert!(error.diagnostic_source().is_some()); }