assertor 0.0.4

Fluent assertion library with readable failure messages.
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
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238

// Copyright 2021 Google LLC
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
//      http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.

use std::borrow::Borrow;
use std::fmt::Debug;

use crate::assert_that;
use crate::base::{AssertionApi, AssertionResult, AssertionStrategy, Subject};

/// Trait for result assertion.
///
/// # Example
/// ```
/// use assertor::*;
///
/// let ok : Result<usize, usize>= Ok(0);
/// let err : Result<usize, usize>= Err(1);
///
/// assert_that!(ok).is_ok();
/// assert_that!(err).is_err();
/// assert_that!(ok).has_ok(0);
/// assert_that!(err).has_err(1);
/// ```
pub trait ResultAssertion<R, OK, ERR> {
    /// Checks that the subject is [`Result::Ok(_)`](`std::result::Result::Ok`).
    #[track_caller]
    fn is_ok(&self) -> R;

    /// Checks that the subject is [`Result::Err(_)`](`std::result::Result::Err`).
    #[track_caller]
    fn is_err(&self) -> R;

    /// Checks that the subject is [`Result::Ok(expected)`](`std::result::Result::Err`).
    #[track_caller]
    fn has_ok<B: Borrow<OK>>(&self, expected: B) -> R
        where
            OK: PartialEq;

    /// Checks that the subject is [`Result::Err(expected)`](`std::result::Result::Err`).
    #[track_caller]
    fn has_err<B: Borrow<ERR>>(&self, expected: B) -> R
        where
            ERR: PartialEq;

    /// Returns a new subject which is the ok value of the subject if the subject has ok value. Otherwise, it fails.
    #[track_caller]
    fn ok(&self) -> Subject<OK, (), R>;

    /// Returns a new subject which is the error value of the subject if the subject has error value. Otherwise, it fails.
    #[track_caller]
    fn err(&self) -> Subject<ERR, (), R>;
}

impl<R, OK: Debug, ERR: Debug> ResultAssertion<R, OK, ERR> for Subject<'_, Result<OK, ERR>, (), R>
    where
        AssertionResult: AssertionStrategy<R>,
{
    fn is_ok(&self) -> R {
        if self.actual().is_ok() {
            self.new_result().do_ok()
        } else {
            self.new_result()
                .add_fact("expected", "Result::Err")
                .add_fact("actual", "Result::Ok")
                .add_splitter()
                .add_fact("actual", format!("{:?}", self.actual()))
                .do_fail()
        }
    }

    fn is_err(&self) -> R {
        if self.actual().is_err() {
            self.new_result().do_ok()
        } else {
            self.new_result()
                .add_fact("expected", "Result::Err")
                .add_fact("actual", "Result::Ok")
                .add_splitter()
                .add_fact("actual", format!("{:?}", self.actual()))
                .do_fail()
        }
    }

    fn has_ok<B: Borrow<OK>>(&self, expected: B) -> R
        where
            OK: PartialEq,
    {
        match self.actual() {
            Ok(actual) if actual.eq(expected.borrow()) => self.new_result().do_ok(),
            Ok(actual) => self
                .new_result()
                .add_fact("expected", format!("Ok({:?})", expected.borrow()))
                .add_fact("actual", format!("Ok({:?})", actual))
                .do_fail(),
            Err(actual) => self
                .new_result()
                .add_fact("expected", format!("Ok({:?})", expected.borrow()))
                .add_fact("actual", format!("Err({:?})", actual))
                .do_fail(),
        }
    }

    fn has_err<B: Borrow<ERR>>(&self, expected: B) -> R
        where
            ERR: PartialEq,
    {
        match self.actual() {
            Err(actual) if actual.eq(expected.borrow()) => self.new_result().do_ok(),
            Err(actual) => self
                .new_result()
                .add_fact("expected", format!("Err({:?})", expected.borrow()))
                .add_fact("actual", format!("Err({:?})", actual))
                .do_fail(),
            Ok(actual) => self
                .new_result()
                .add_fact("expected", format!("Err({:?})", expected.borrow()))
                .add_fact("actual", format!("Ok({:?})", actual))
                .do_fail(),
        }
    }

    fn ok(&self) -> Subject<OK, (), R> {
        assert_that!(*self.actual()).is_ok();
        self.new_subject(self.actual().as_ref().ok().unwrap(), Some(format!("{}.ok", self.description_or_expr())), ())
    }

    fn err(&self) -> Subject<ERR, (), R> {
        assert_that!(*self.actual()).is_err();
        self.new_subject(self.actual().as_ref().err().unwrap(), Some(format!("{}.err", self.description_or_expr())), ())
    }
}

#[cfg(test)]
mod tests {
    use crate::ComparableAssertion;
    use crate::testing::*;

    use super::*;

    #[test]
    fn is_ok() {
        assert_that!(Result::<_, ()>::Ok(0)).is_ok();
        assert_that!(Result::<_, ()>::Ok("23")).is_ok();
        assert_that!(Result::<_, ()>::Ok(())).is_ok();
    }

    #[test]
    fn is_err() {
        assert_that!(Result::<(), _>::Err(0)).is_err();
        assert_that!(Result::<(), _>::Err("23")).is_err();
        assert_that!(Result::<(), _>::Err(())).is_err();
    }

    #[test]
    fn has_ok() {
        assert_that!(Result::<_, ()>::Ok(0)).has_ok(0);
        assert_that!(Result::<_, ()>::Ok("23")).has_ok("23");
        assert_that!(Result::<_, ()>::Ok(())).has_ok(());

        // Failures
        assert_that!(check_that!(Result::<_, ()>::Ok(0)).has_ok(1)).facts_are(vec![
            Fact::new("expected", "Ok(1)"),
            Fact::new("actual", "Ok(0)"),
        ]);
        assert_that!(check_that!(Result::<(), ()>::Err(())).has_ok(())).facts_are(vec![
            Fact::new("expected", "Ok(())"),
            Fact::new("actual", "Err(())"),
        ]);
        assert_that!(check_that!(Result::<&str, &str>::Err("")).has_ok("")).facts_are(vec![
            Fact::new("expected", r#"Ok("")"#),
            Fact::new("actual", r#"Err("")"#),
        ]);
        assert_that!(check_that!(Result::<&str, &str>::Ok("")).has_ok("expected")).facts_are(vec![
            Fact::new("expected", r#"Ok("expected")"#),
            Fact::new("actual", r#"Ok("")"#),
        ]);
    }

    #[test]
    fn has_err() {
        assert_that!(Result::<(), _>::Err(0)).has_err(0);
        assert_that!(Result::<(), _>::Err("23")).has_err("23");
        assert_that!(Result::<(), _>::Err(())).has_err(());

        // Failures
        assert_that!(check_that!(Result::<(), _>::Err(0)).has_err(1)).facts_are(vec![
            Fact::new("expected", "Err(1)"),
            Fact::new("actual", "Err(0)"),
        ]);
        assert_that!(check_that!(Result::<(), ()>::Ok(())).has_err(())).facts_are(vec![
            Fact::new("expected", "Err(())"),
            Fact::new("actual", "Ok(())"),
        ]);
        assert_that!(check_that!(Result::<&str, &str>::Ok("")).has_err("")).facts_are(vec![
            Fact::new("expected", r#"Err("")"#),
            Fact::new("actual", r#"Ok("")"#),
        ]);
        assert_that!(check_that!(Result::<&str, &str>::Err("")).has_err("expected")).facts_are(
            vec![
                Fact::new("expected", r#"Err("expected")"#),
                Fact::new("actual", r#"Err("")"#),
            ],
        );
    }

    #[test]
    fn ok() {
        assert_that!(Result::<f64,()>::Ok(0.)).ok().is_at_most(1.);
    }

    #[test]
    #[should_panic]
    fn ok_panic() {
        assert_that!(Result::<f64,()>::Err(())).ok().is_at_most(1.);
    }

    #[test]
    fn err() {
        assert_that!(Result::<(), f64>::Err(0.)).err().is_at_most(1.);
    }

    #[test]
    #[should_panic]
    fn err_panic() {
        assert_that!(Result::<(), f64>::Ok(())).err().is_at_most(1.);
    }
}