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

//-
// Copyright 2017 Jason Lingle
//
// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
// option. This file may not be copied, modified, or distributed
// except according to those terms.

//! Support for combining strategies into tuples.
//!
//! There is no explicit "tuple strategy"; simply make a tuple containing the
//! strategy and that tuple is itself a strategy.

use crate::strategy::*;
use crate::test_runner::*;

/// Common `ValueTree` implementation for all tuple strategies.
#[derive(Clone, Copy, Debug)]
pub struct TupleValueTree<T> {
    tree: T,
    shrinker: u32,
    prev_shrinker: Option<u32>,
}

impl<T> TupleValueTree<T> {
    /// Create a new `TupleValueTree` wrapping `inner`.
    ///
    /// It only makes sense for `inner` to be a tuple of an arity for which the
    /// type implements `ValueTree`.
    pub fn new(inner: T) -> Self {
        TupleValueTree {
            tree: inner,
            shrinker: 0,
            prev_shrinker: None,
        }
    }
}

macro_rules! tuple {
    ($($fld:tt : $typ:ident),*) => {
        impl<$($typ : Strategy),*> Strategy for ($($typ,)*) {
            type Tree = TupleValueTree<($($typ::Tree,)*)>;
            type Value = ($($typ::Value,)*);

            fn new_tree(&self, runner: &mut TestRunner) -> NewTree<Self> {
                let values = ($(self.$fld.new_tree(runner)?,)*);
                Ok(TupleValueTree::new(values))
            }
        }

        impl<$($typ : ValueTree),*> ValueTree
        for TupleValueTree<($($typ,)*)> {
            type Value = ($($typ::Value,)*);

            fn current(&self) -> Self::Value {
                ($(self.tree.$fld.current(),)*)
            }

            fn simplify(&mut self) -> bool {
                $(
                    if $fld == self.shrinker {
                        if self.tree.$fld.simplify() {
                            self.prev_shrinker = Some(self.shrinker);
                            return true;
                        } else {
                            self.shrinker += 1;
                        }
                    }
                )*
                false
            }

            fn complicate(&mut self) -> bool {
                if let Some(shrinker) = self.prev_shrinker {$(
                    if $fld == shrinker {
                        if self.tree.$fld.complicate() {
                            self.shrinker = shrinker;
                            return true;
                        } else {
                            self.prev_shrinker = None;
                            return false;
                        }
                    }
                )*}
                false
            }
        }
    }
}

tuple!(0: A);
tuple!(0: A, 1: B);
tuple!(0: A, 1: B, 2: C);
tuple!(0: A, 1: B, 2: C, 3: D);
tuple!(0: A, 1: B, 2: C, 3: D, 4: E);
tuple!(0: A, 1: B, 2: C, 3: D, 4: E, 5: F);
tuple!(0: A, 1: B, 2: C, 3: D, 4: E, 5: F, 6: G);
tuple!(0: A, 1: B, 2: C, 3: D, 4: E, 5: F, 6: G, 7: H);
tuple!(0: A, 1: B, 2: C, 3: D, 4: E, 5: F, 6: G, 7: H, 8: I);
tuple!(0: A, 1: B, 2: C, 3: D, 4: E, 5: F, 6: G, 7: H, 8: I, 9: J);
tuple!(
    0: A,
    1: B,
    2: C,
    3: D,
    4: E,
    5: F,
    6: G,
    7: H,
    8: I,
    9: J,
    10: K
);
tuple!(
    0: A,
    1: B,
    2: C,
    3: D,
    4: E,
    5: F,
    6: G,
    7: H,
    8: I,
    9: J,
    10: K,
    11: L
);

#[cfg(test)]
mod test {
    use crate::strategy::*;

    use super::*;

    #[test]
    fn shrinks_fully_ltr() {
        fn pass(a: (i32, i32)) -> bool {
            a.0 * a.1 <= 9
        }

        let input = (0..32, 0..32);
        let mut runner = TestRunner::default();

        let mut cases_tested = 0;
        for _ in 0..256 {
            // Find a failing test case
            let mut case = input.new_tree(&mut runner).unwrap();
            if pass(case.current()) {
                continue;
            }

            loop {
                if pass(case.current()) {
                    if !case.complicate() {
                        break;
                    }
                } else {
                    if !case.simplify() {
                        break;
                    }
                }
            }

            let last = case.current();
            assert!(!pass(last));
            // Maximally shrunken
            assert!(pass((last.0 - 1, last.1)));
            assert!(pass((last.0, last.1 - 1)));

            cases_tested += 1;
        }

        assert!(cases_tested > 32, "Didn't find enough test cases");
    }

    #[test]
    fn test_sanity() {
        check_strategy_sanity((0i32..100, 0i32..1000, 0i32..10000), None);
    }
}