proptest/tuple.rs
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//-
// 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);
}
}