claims/
assert_some.rs

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
157
158
159
160
161
162
163
/// Asserts that the expression matches a [`Some(_)`] variant, returning the contained value.
///
/// ## Uses
///
/// Assertions are always checked in both debug and release builds, and cannot be disabled.
/// See [`debug_assert_some!`] for assertions that are not enabled in release builds by default.
///
/// ## Custom messages
///
/// This macro has a second form, where a custom panic message can be provided with or without
/// arguments for formatting. See [`std::fmt`] for syntax for this form.
///
/// ## Examples
///
/// ```rust
/// # #[macro_use] extern crate claims;
/// # fn main() {
/// let maybe = Some(42);
///
/// assert_some!(maybe);
///
/// // With a custom message
/// assert_some!(maybe, "Found it at {:?}", maybe);
/// # }
/// ```
///
/// A `None` variant will panic:
///
/// ```rust,should_panic
/// # #[macro_use] extern crate claims;
/// # fn main() {
/// let maybe = None;
///
/// assert_some!(maybe);  // Will panic
/// # }
/// ```
///
/// [`Some(_)`]: https://doc.rust-lang.org/core/option/enum.Option.html#variant.Some
/// [`std::fmt`]: https://doc.rust-lang.org/std/fmt/index.html
/// [`debug_assert_some!`]: crate::debug_assert_some!
#[macro_export]
macro_rules! assert_some {
    ($cond:expr $(,)?) => {
        match $cond {
            ::core::option::Option::Some(t) => t,
            ::core::option::Option::None => {
                ::core::panic!("assertion failed, expected Some(_), got None");
            }
        }
    };
    ($cond:expr, $($arg:tt)+) => {
        match $cond {
            ::core::option::Option::Some(t) => t,
            ::core::option::Option::None => {
                ::core::panic!("assertion failed, expected Some(_), got None: {}", ::core::format_args!($($arg)+));
            }
        }
    };
}

/// Asserts that the expression matches a [`Some(_)`] variant on debug builds.
///
/// This macro behaves nearly the same as [`assert_some!`] on debug builds, although it does not
/// return the value contained in the `Some` variant. On release builds it is a no-op.
///
/// [`Some(_)`]: https://doc.rust-lang.org/core/option/enum.Option.html#variant.Some
#[macro_export]
macro_rules! debug_assert_some {
    ($($arg:tt)*) => {
        #[cfg(debug_assertions)]
        $crate::assert_some!($($arg)*);
    }
}

#[cfg(test)]
mod tests {
    #[test]
    fn some() {
        assert_some!(Some(()));
    }

    #[test]
    #[should_panic(expected = "assertion failed, expected Some(_), got None")]
    fn not_some() {
        assert_some!(None::<()>);
    }

    #[test]
    #[should_panic(expected = "assertion failed, expected Some(_), got None: foo")]
    fn not_some_custom_message() {
        assert_some!(None::<()>, "foo");
    }

    #[test]
    fn some_value_returned() {
        let value = assert_some!(Some(42));
        assert_eq!(value, 42);
    }

    #[test]
    #[cfg_attr(not(debug_assertions), ignore = "only run in debug mode")]
    fn debug_some() {
        debug_assert_some!(Some(()));
    }

    #[test]
    #[cfg_attr(not(debug_assertions), ignore = "only run in debug mode")]
    #[should_panic(expected = "assertion failed, expected Some(_), got None")]
    fn debug_not_some() {
        debug_assert_some!(None::<()>);
    }

    #[test]
    #[cfg_attr(not(debug_assertions), ignore = "only run in debug mode")]
    #[should_panic(expected = "assertion failed, expected Some(_), got None: foo")]
    fn debug_not_some_custom_message() {
        debug_assert_some!(None::<()>, "foo");
    }

    #[test]
    #[cfg_attr(debug_assertions, ignore = "only run in release mode")]
    fn debug_release_not_some() {
        debug_assert_some!(None::<()>);
    }

    #[test]
    fn does_not_require_some_to_impl_debug() {
        enum Foo {
            Bar,
        }

        assert_some!(Some(Foo::Bar));
    }

    #[test]
    fn debug_does_not_require_some_to_impl_debug() {
        #[allow(dead_code)]
        enum Foo {
            Bar,
        }

        debug_assert_some!(Some(Foo::Bar));
    }

    #[test]
    fn does_not_require_some_to_impl_debug_custom_message() {
        enum Foo {
            Bar,
        }

        assert_some!(Some(Foo::Bar), "foo");
    }

    #[test]
    fn debug_does_not_require_some_to_impl_debug_custom_message() {
        #[allow(dead_code)]
        enum Foo {
            Bar,
        }

        debug_assert_some!(Some(Foo::Bar), "foo");
    }
}