test_case_macros/
lib.rs

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1extern crate proc_macro;
2
3use proc_macro::TokenStream;
4
5use proc_macro2::Span as Span2;
6use syn::{parse_macro_input, ItemFn, Path};
7
8use quote::quote;
9use syn::parse_quote;
10use syn::spanned::Spanned;
11use test_case_core::{TestCase, TestMatrix};
12
13/// Generates tests for given set of data
14///
15/// In general, test case consists of four elements:
16///
17/// 1. _(Required)_ Arguments passed to test body
18/// 2. _(Optional)_ Expected result
19/// 3. _(Optional)_ Test case description
20/// 4. _(Required)_ Test body
21///
22///  When _expected result_ is provided, it is compared against the actual value generated with _test body_ using `assert_eq!`.
23/// _Test cases_ that don't provide _expected result_ should contain custom assertions within _test body_ or return `Result` similar to `#[test]` macro.
24#[proc_macro_attribute]
25pub fn test_case(args: TokenStream, input: TokenStream) -> TokenStream {
26    let test_case = parse_macro_input!(args as TestCase);
27    let mut item = parse_macro_input!(input as ItemFn);
28
29    let mut test_cases = vec![(test_case, Span2::call_site())];
30
31    match expand_additional_test_case_macros(&mut item) {
32        Ok(cases) => test_cases.extend(cases),
33        Err(err) => return err.into_compile_error().into(),
34    }
35
36    render_test_cases(&test_cases, item)
37}
38
39/// Generates tests for the cartesian product of a given set of data
40///
41/// A test matrix consists of four elements:
42///
43/// 1. _(Required)_ Sets of values to combine; the number of sets must be the same as the number of
44///    arguments to the test body function
45/// 2. _(Optional)_ Expected result (for all combinations of values)
46/// 3. _(Optional)_ Test case description (applied as a prefix the generated name of the test)
47/// 4. _(Required)_ Test body
48///
49/// _Expected result_ and _Test body_ are the same as they are for the singular `#[test_case(...)]`
50/// macro but are applied to every case generated by `#[test_matrix(...)]`.
51#[proc_macro_attribute]
52pub fn test_matrix(args: TokenStream, input: TokenStream) -> TokenStream {
53    let matrix = parse_macro_input!(args as TestMatrix);
54    let mut item = parse_macro_input!(input as ItemFn);
55
56    let mut test_cases = expand_test_matrix(&matrix, Span2::call_site());
57
58    match expand_additional_test_case_macros(&mut item) {
59        Ok(cases) => test_cases.extend(cases),
60        Err(err) => return err.into_compile_error().into(),
61    }
62
63    render_test_cases(&test_cases, item)
64}
65
66fn expand_test_matrix(matrix: &TestMatrix, span: Span2) -> Vec<(TestCase, Span2)> {
67    matrix.cases().map(|c| (c, span)).collect()
68}
69
70fn expand_additional_test_case_macros(item: &mut ItemFn) -> syn::Result<Vec<(TestCase, Span2)>> {
71    let mut additional_cases = vec![];
72    let mut attrs_to_remove = vec![];
73    let legal_test_case_names: [Path; 4] = [
74        parse_quote!(test_case),
75        parse_quote!(test_case::test_case),
76        parse_quote!(test_case::case),
77        parse_quote!(case),
78    ];
79    let legal_test_matrix_names: [Path; 2] = [
80        parse_quote!(test_matrix),
81        parse_quote!(test_case::test_matrix),
82    ];
83
84    for (idx, attr) in item.attrs.iter().enumerate() {
85        if legal_test_case_names.contains(attr.path()) {
86            let test_case = match attr.parse_args::<TestCase>() {
87                Ok(test_case) => test_case,
88                Err(err) => {
89                    return Err(syn::Error::new(
90                        attr.span(),
91                        format!("cannot parse test_case arguments: {err}"),
92                    ))
93                }
94            };
95            additional_cases.push((test_case, attr.span()));
96            attrs_to_remove.push(idx);
97        } else if legal_test_matrix_names.contains(attr.path()) {
98            let test_matrix = match attr.parse_args::<TestMatrix>() {
99                Ok(test_matrix) => test_matrix,
100                Err(err) => {
101                    return Err(syn::Error::new(
102                        attr.span(),
103                        format!("cannot parse test_matrix arguments: {err}"),
104                    ))
105                }
106            };
107            additional_cases.extend(expand_test_matrix(&test_matrix, attr.span()));
108            attrs_to_remove.push(idx);
109        }
110    }
111
112    for i in attrs_to_remove.into_iter().rev() {
113        item.attrs.swap_remove(i);
114    }
115
116    Ok(additional_cases)
117}
118
119#[allow(unused_mut)]
120fn render_test_cases(test_cases: &[(TestCase, Span2)], mut item: ItemFn) -> TokenStream {
121    let mut rendered_test_cases = vec![];
122
123    for (test_case, span) in test_cases {
124        rendered_test_cases.push(test_case.render(item.clone(), *span));
125    }
126
127    let mod_name = item.sig.ident.clone();
128
129    // We don't want any external crate to alter main fn code, we are passing attributes to each sub-function anyway
130    item.attrs.retain(|attr| {
131        attr.path()
132            .get_ident()
133            .map(|ident| ident == "allow")
134            .unwrap_or(false)
135    });
136
137    let output = quote! {
138        #[allow(unused_attributes)]
139        #item
140
141        #[cfg(test)]
142        mod #mod_name {
143            #[allow(unused_imports)]
144            use super::*;
145
146            #(#rendered_test_cases)*
147        }
148    };
149
150    output.into()
151}
test_case_macros/lib.rs

test_case_macros/
lib.rs
