test-context-macros 0.5.7

Macro crate for test-context
Documentation 
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156

mod macro_args;
mod test_args;

use crate::test_args::{ContextArg, ContextArgMode, TestArg};
use macro_args::MacroArgs;
use proc_macro::TokenStream;
use quote::{format_ident, quote};
use syn::ItemFn;

/// Macro to use on tests to add the setup/teardown functionality of your context.
///
/// Ordering of this attribute is important, and typically `test_context` should come
/// before other test attributes. For example, the following is valid:
///
/// ```ignore
/// #[test_context(MyContext)]
/// #[test]
/// fn my_test() {
/// }
/// ```
///
/// The following is NOT valid...
///
/// ```ignore
/// #[test]
/// #[test_context(MyContext)]
/// fn my_test() {
/// }
/// ```
#[proc_macro_attribute]
pub fn test_context(attr: TokenStream, item: TokenStream) -> TokenStream {
    let args = syn::parse_macro_input!(attr as MacroArgs);
    let input = syn::parse_macro_input!(item as syn::ItemFn);

    let (input, context_args) = remove_context_args(input, args.context_type.clone());

    if context_args.len() != 1 {
        panic!("Exactly one Context argument must be defined");
    }

    let context_arg = context_args.into_iter().next().unwrap();

    if !args.skip_teardown && context_arg.mode.is_owned() {
        panic!(
            "It is not possible to take ownership of the context if the teardown has to be ran."
        );
    }

    let input = refactor_input_body(input, &args, context_arg);

    quote! { #input }.into()
}

fn remove_context_args(
    mut input: syn::ItemFn,
    expected_context_type: syn::Type,
) -> (syn::ItemFn, Vec<ContextArg>) {
    let test_args: Vec<TestArg> = input
        .sig
        .inputs
        .into_iter()
        .map(|arg| TestArg::parse_arg_with_expected_context(arg, &expected_context_type))
        .collect();

    let context_args: Vec<ContextArg> = test_args
        .iter()
        .cloned()
        .filter_map(|arg| match arg {
            TestArg::Any(_) => None,
            TestArg::Context(context_arg_info) => Some(context_arg_info),
        })
        .collect();

    let new_args: syn::punctuated::Punctuated<_, _> = test_args
        .into_iter()
        .filter_map(|arg| match arg {
            TestArg::Any(fn_arg) => Some(fn_arg),
            TestArg::Context(_) => None,
        })
        .collect();

    input.sig.inputs = new_args;

    (input, context_args)
}

fn refactor_input_body(
    input: syn::ItemFn,
    args: &MacroArgs,
    context_arg: ContextArg,
) -> syn::ItemFn {
    let context_type = &args.context_type;
    let result_name = format_ident!("wrapped_result");
    let body = &input.block;
    let is_async = input.sig.asyncness.is_some();
    let context_pattern = context_arg.pattern;

    let context_binding = match context_arg.mode {
        ContextArgMode::Owned => quote! { let #context_pattern = __context; },
        ContextArgMode::Reference => quote! { let #context_pattern = &__context; },
        ContextArgMode::MutableReference => quote! { let #context_pattern = &mut __context; },
    };

    let body = if args.skip_teardown && is_async {
        quote! {
            use test_context::futures::FutureExt;
            let mut __context = <#context_type as test_context::AsyncTestContext>::setup().await;
            #context_binding
            let #result_name = std::panic::AssertUnwindSafe( async { #body } ).catch_unwind().await;
        }
    } else if args.skip_teardown && !is_async {
        quote! {
            let mut __context = <#context_type as test_context::TestContext>::setup();
            let #result_name = std::panic::catch_unwind(std::panic::AssertUnwindSafe(|| {
                #context_binding
                #body
            }));
        }
    } else if !args.skip_teardown && is_async {
        quote! {
            use test_context::futures::FutureExt;
            let mut __context = <#context_type as test_context::AsyncTestContext>::setup().await;
            #context_binding
            let #result_name = std::panic::AssertUnwindSafe( async { #body } ).catch_unwind().await;
            <#context_type as test_context::AsyncTestContext>::teardown(__context).await;
        }
    }
    // !args.skip_teardown && !is_async
    else {
        quote! {
            let mut __context = <#context_type as test_context::TestContext>::setup();
            let #result_name = std::panic::catch_unwind(std::panic::AssertUnwindSafe(|| {
                #context_binding
                #body
            }));
            <#context_type as test_context::TestContext>::teardown(__context);
        }
    };

    let body = quote! {
        {
            #body
            match #result_name {
                Ok(value) => value,
                Err(err) => {
                    std::panic::resume_unwind(err);
                }
            }
        }
    };

    ItemFn {
        block: Box::new(syn::parse2(body).unwrap()),
        ..input
    }
}