src/tester.rs - platform/external/rust/crates/quickcheck - Gitiles

 use std::cmp;
 use std::env;
 use std::fmt::Debug;
 use std::panic;

 use crate::{
     tester::Status::{Discard, Fail, Pass},
     Arbitrary, Gen,
 };

 /// The main QuickCheck type for setting configuration and running QuickCheck.
 pub struct QuickCheck {
     tests: u64,
     max_tests: u64,
     min_tests_passed: u64,
     gen: Gen,
 }

 fn qc_tests() -> u64 {
     let default = 100;
     match env::var("QUICKCHECK_TESTS") {
         Ok(val) => val.parse().unwrap_or(default),
         Err(_) => default,
     }
 }

 fn qc_max_tests() -> u64 {
     let default = 10_000;
     match env::var("QUICKCHECK_MAX_TESTS") {
         Ok(val) => val.parse().unwrap_or(default),
         Err(_) => default,
     }
 }

 fn qc_gen_size() -> usize {
     let default = 100;
     match env::var("QUICKCHECK_GENERATOR_SIZE") {
         Ok(val) => val.parse().unwrap_or(default),
         Err(_) => default,
     }
 }

 fn qc_min_tests_passed() -> u64 {
     let default = 0;
     match env::var("QUICKCHECK_MIN_TESTS_PASSED") {
         Ok(val) => val.parse().unwrap_or(default),
         Err(_) => default,
     }
 }

 impl QuickCheck {
     /// Creates a new QuickCheck value.
     ///
     /// This can be used to run QuickCheck on things that implement `Testable`.
     /// You may also adjust the configuration, such as the number of tests to
     /// run.
     ///
     /// By default, the maximum number of passed tests is set to `100`, the max
     /// number of overall tests is set to `10000` and the generator is created
     /// with a size of `100`.
     pub fn new() -> QuickCheck {
         let gen = Gen::new(qc_gen_size());
         let tests = qc_tests();
         let max_tests = cmp::max(tests, qc_max_tests());
         let min_tests_passed = qc_min_tests_passed();

         QuickCheck { tests, max_tests, min_tests_passed, gen }
     }

     /// Set the random number generator to be used by QuickCheck.
     pub fn gen(self, gen: Gen) -> QuickCheck {
         QuickCheck { gen, ..self }
     }

     /// Set the number of tests to run.
     ///
     /// This actually refers to the maximum number of *passed* tests that
     /// can occur. Namely, if a test causes a failure, future testing on that
     /// property stops. Additionally, if tests are discarded, there may be
     /// fewer than `tests` passed.
     pub fn tests(mut self, tests: u64) -> QuickCheck {
         self.tests = tests;
         self
     }

     /// Set the maximum number of tests to run.
     ///
     /// The number of invocations of a property will never exceed this number.
     /// This is necessary to cap the number of tests because QuickCheck
     /// properties can discard tests.
     pub fn max_tests(mut self, max_tests: u64) -> QuickCheck {
         self.max_tests = max_tests;
         self
     }

     /// Set the minimum number of tests that needs to pass.
     ///
     /// This actually refers to the minimum number of *valid* *passed* tests
     /// that needs to pass for the property to be considered successful.
     pub fn min_tests_passed(mut self, min_tests_passed: u64) -> QuickCheck {
         self.min_tests_passed = min_tests_passed;
         self
     }

     /// Tests a property and returns the result.
     ///
     /// The result returned is either the number of tests passed or a witness
     /// of failure.
     ///
     /// (If you're using Rust's unit testing infrastructure, then you'll
     /// want to use the `quickcheck` method, which will `panic!` on failure.)
     pub fn quicktest<A>(&mut self, f: A) -> Result<u64, TestResult>
     where
         A: Testable,
     {
         let mut n_tests_passed = 0;
         for _ in 0..self.max_tests {
             if n_tests_passed >= self.tests {
                 break;
             }
             match f.result(&mut self.gen) {
                 TestResult { status: Pass, .. } => n_tests_passed += 1,
                 TestResult { status: Discard, .. } => continue,
                 r @ TestResult { status: Fail, .. } => return Err(r),
             }
         }
         Ok(n_tests_passed)
     }

     /// Tests a property and calls `panic!` on failure.
     ///
     /// The `panic!` message will include a (hopefully) minimal witness of
     /// failure.
     ///
     /// It is appropriate to use this method with Rust's unit testing
     /// infrastructure.
     ///
     /// Note that if the environment variable `RUST_LOG` is set to enable
     /// `info` level log messages for the `quickcheck` crate, then this will
     /// include output on how many QuickCheck tests were passed.
     ///
     /// # Example
     ///
     /// ```rust
     /// use quickcheck::QuickCheck;
     ///
     /// fn prop_reverse_reverse() {
     ///     fn revrev(xs: Vec<usize>) -> bool {
     ///         let rev: Vec<_> = xs.clone().into_iter().rev().collect();
     ///         let revrev: Vec<_> = rev.into_iter().rev().collect();
     ///         xs == revrev
     ///     }
     ///     QuickCheck::new().quickcheck(revrev as fn(Vec<usize>) -> bool);
     /// }
     /// ```
     pub fn quickcheck<A>(&mut self, f: A)
     where
         A: Testable,
     {
         // Ignore log init failures, implying it has already been done.
         let _ = crate::env_logger_init();

         let n_tests_passed = match self.quicktest(f) {
             Ok(n_tests_passed) => n_tests_passed,
             Err(result) => panic!(result.failed_msg()),
         };

         if n_tests_passed >= self.min_tests_passed {
             info!("(Passed {} QuickCheck tests.)", n_tests_passed)
         } else {
             panic!(
                 "(Unable to generate enough tests, {} not discarded.)",
                 n_tests_passed
             )
         }
     }
 }

 /// Convenience function for running QuickCheck.
 ///
 /// This is an alias for `QuickCheck::new().quickcheck(f)`.
 pub fn quickcheck<A: Testable>(f: A) {
     QuickCheck::new().quickcheck(f)
 }

 /// Describes the status of a single instance of a test.
 ///
 /// All testable things must be capable of producing a `TestResult`.
 #[derive(Clone, Debug)]
 pub struct TestResult {
     status: Status,
     arguments: Vec<String>,
     err: Option<String>,
 }

 /// Whether a test has passed, failed or been discarded.
 #[derive(Clone, Debug)]
 enum Status {
     Pass,
     Fail,
     Discard,
 }

 impl TestResult {
     /// Produces a test result that indicates the current test has passed.
     pub fn passed() -> TestResult {
         TestResult::from_bool(true)
     }

     /// Produces a test result that indicates the current test has failed.
     pub fn failed() -> TestResult {
         TestResult::from_bool(false)
     }

     /// Produces a test result that indicates failure from a runtime error.
     pub fn error<S: Into<String>>(msg: S) -> TestResult {
         let mut r = TestResult::from_bool(false);
         r.err = Some(msg.into());
         r
     }

     /// Produces a test result that instructs `quickcheck` to ignore it.
     /// This is useful for restricting the domain of your properties.
     /// When a test is discarded, `quickcheck` will replace it with a
     /// fresh one (up to a certain limit).
     pub fn discard() -> TestResult {
         TestResult { status: Discard, arguments: vec![], err: None }
     }

     /// Converts a `bool` to a `TestResult`. A `true` value indicates that
     /// the test has passed and a `false` value indicates that the test
     /// has failed.
     pub fn from_bool(b: bool) -> TestResult {
         TestResult {
             status: if b { Pass } else { Fail },
             arguments: vec![],
             err: None,
         }
     }

     /// Tests if a "procedure" fails when executed. The test passes only if
     /// `f` generates a task failure during its execution.
     pub fn must_fail<T, F>(f: F) -> TestResult
     where
         F: FnOnce() -> T,
         F: 'static,
         T: 'static,
     {
         let f = panic::AssertUnwindSafe(f);
         TestResult::from_bool(panic::catch_unwind(f).is_err())
     }

     /// Returns `true` if and only if this test result describes a failing
     /// test.
     pub fn is_failure(&self) -> bool {
         match self.status {
             Fail => true,
             Pass | Discard => false,
         }
     }

     /// Returns `true` if and only if this test result describes a failing
     /// test as a result of a run time error.
     pub fn is_error(&self) -> bool {
         self.is_failure() && self.err.is_some()
     }

     fn failed_msg(&self) -> String {
         match self.err {
             None => format!(
                 "[quickcheck] TEST FAILED. Arguments: ({})",
                 self.arguments.join(", ")
             ),
             Some(ref err) => format!(
                 "[quickcheck] TEST FAILED (runtime error). \
                  Arguments: ({})\nError: {}",
                 self.arguments.join(", "),
                 err
             ),
         }
     }
 }

 /// `Testable` describes types (e.g., a function) whose values can be
 /// tested.
 ///
 /// Anything that can be tested must be capable of producing a `TestResult`
 /// given a random number generator. This is trivial for types like `bool`,
 /// which are just converted to either a passing or failing test result.
 ///
 /// For functions, an implementation must generate random arguments
 /// and potentially shrink those arguments if they produce a failure.
 ///
 /// It's unlikely that you'll have to implement this trait yourself.
 pub trait Testable: 'static {
     fn result(&self, _: &mut Gen) -> TestResult;
 }

 impl Testable for bool {
     fn result(&self, _: &mut Gen) -> TestResult {
         TestResult::from_bool(*self)
     }
 }

 impl Testable for () {
     fn result(&self, _: &mut Gen) -> TestResult {
         TestResult::passed()
     }
 }

 impl Testable for TestResult {
     fn result(&self, _: &mut Gen) -> TestResult {
         self.clone()
     }
 }

 impl<A, E> Testable for Result<A, E>
 where
     A: Testable,
     E: Debug + 'static,
 {
     fn result(&self, g: &mut Gen) -> TestResult {
         match *self {
             Ok(ref r) => r.result(g),
             Err(ref err) => TestResult::error(format!("{:?}", err)),
         }
     }
 }

 /// Return a vector of the debug formatting of each item in `args`
 fn debug_reprs(args: &[&dyn Debug]) -> Vec<String> {
     args.iter().map(|x| format!("{:?}", x)).collect()
 }

 macro_rules! testable_fn {
     ($($name: ident),*) => {

 impl<T: Testable,
      $($name: Arbitrary + Debug),*> Testable for fn($($name),*) -> T {
     #[allow(non_snake_case)]
     fn result(&self, g: &mut Gen) -> TestResult {
         fn shrink_failure<T: Testable, $($name: Arbitrary + Debug),*>(
             g: &mut Gen,
             self_: fn($($name),*) -> T,
             a: ($($name,)*),
         ) -> Option<TestResult> {
             for t in a.shrink() {
                 let ($($name,)*) = t.clone();
                 let mut r_new = safe(move || {self_($($name),*)}).result(g);
                 if r_new.is_failure() {
                     {
                         let ($(ref $name,)*) : ($($name,)*) = t;
                         r_new.arguments = debug_reprs(&[$($name),*]);
                     }

                     // The shrunk value *does* witness a failure, so keep
                     // trying to shrink it.
                     let shrunk = shrink_failure(g, self_, t);

                     // If we couldn't witness a failure on any shrunk value,
                     // then return the failure we already have.
                     return Some(shrunk.unwrap_or(r_new))
                 }
             }
             None
         }

         let self_ = *self;
         let a: ($($name,)*) = Arbitrary::arbitrary(g);
         let ( $($name,)* ) = a.clone();
         let mut r = safe(move || {self_($($name),*)}).result(g);

         {
             let ( $(ref $name,)* ) = a;
             r.arguments = debug_reprs(&[$($name),*]);
         }
         match r.status {
             Pass|Discard => r,
             Fail => {
                 shrink_failure(g, self_, a).unwrap_or(r)
             }
         }
     }
 }}}

 testable_fn!();
 testable_fn!(A);
 testable_fn!(A, B);
 testable_fn!(A, B, C);
 testable_fn!(A, B, C, D);
 testable_fn!(A, B, C, D, E);
 testable_fn!(A, B, C, D, E, F);
 testable_fn!(A, B, C, D, E, F, G);
 testable_fn!(A, B, C, D, E, F, G, H);

 fn safe<T, F>(fun: F) -> Result<T, String>
 where
     F: FnOnce() -> T,
     F: 'static,
     T: 'static,
 {
     panic::catch_unwind(panic::AssertUnwindSafe(fun)).map_err(|any_err| {
         // Extract common types of panic payload:
         // panic and assert produce &str or String
         if let Some(&s) = any_err.downcast_ref::<&str>() {
             s.to_owned()
         } else if let Some(s) = any_err.downcast_ref::<String>() {
             s.to_owned()
         } else {
             "UNABLE TO SHOW RESULT OF PANIC.".to_owned()
         }
     })
 }

 /// Convenient aliases.
 trait AShow: Arbitrary + Debug {}
 impl<A: Arbitrary + Debug> AShow for A {}

 #[cfg(test)]
 mod test {
     use crate::{Gen, QuickCheck};

     #[test]
     fn shrinking_regression_issue_126() {
         fn thetest(vals: Vec<bool>) -> bool {
             vals.iter().filter(|&v| *v).count() < 2
         }
         let failing_case = QuickCheck::new()
             .quicktest(thetest as fn(vals: Vec<bool>) -> bool)
             .unwrap_err();
         let expected_argument = format!("{:?}", [true, true]);
         assert_eq!(failing_case.arguments, vec![expected_argument]);
     }

     #[test]
     fn size_for_small_types_issue_143() {
         fn t(_: i8) -> bool {
             true
         }
         QuickCheck::new().gen(Gen::new(129)).quickcheck(t as fn(i8) -> bool);
     }

     #[test]
     fn regression_signed_shrinker_panic() {
         fn foo_can_shrink(v: i8) -> bool {
             let _ = crate::Arbitrary::shrink(&v).take(100).count();
             true
         }
         crate::quickcheck(foo_can_shrink as fn(i8) -> bool);
     }
 }
	use std::cmp;
	use std::env;
	use std::fmt::Debug;
	use std::panic;

	use crate::{
	tester::Status::{Discard, Fail, Pass},
	Arbitrary, Gen,
	};

	/// The main QuickCheck type for setting configuration and running QuickCheck.
	pub struct QuickCheck {
	tests: u64,
	max_tests: u64,
	min_tests_passed: u64,
	gen: Gen,
	}

	fn qc_tests() -> u64 {
	let default = 100;
	match env::var("QUICKCHECK_TESTS") {
	Ok(val) => val.parse().unwrap_or(default),
	Err(_) => default,
	}
	}

	fn qc_max_tests() -> u64 {
	let default = 10_000;
	match env::var("QUICKCHECK_MAX_TESTS") {
	Ok(val) => val.parse().unwrap_or(default),
	Err(_) => default,
	}
	}

	fn qc_gen_size() -> usize {
	let default = 100;
	match env::var("QUICKCHECK_GENERATOR_SIZE") {
	Ok(val) => val.parse().unwrap_or(default),
	Err(_) => default,
	}
	}

	fn qc_min_tests_passed() -> u64 {
	let default = 0;
	match env::var("QUICKCHECK_MIN_TESTS_PASSED") {
	Ok(val) => val.parse().unwrap_or(default),
	Err(_) => default,
	}
	}

	impl QuickCheck {
	/// Creates a new QuickCheck value.
	///
	/// This can be used to run QuickCheck on things that implement `Testable`.
	/// You may also adjust the configuration, such as the number of tests to
	/// run.
	///
	/// By default, the maximum number of passed tests is set to `100`, the max
	/// number of overall tests is set to `10000` and the generator is created
	/// with a size of `100`.
	pub fn new() -> QuickCheck {
	let gen = Gen::new(qc_gen_size());
	let tests = qc_tests();
	let max_tests = cmp::max(tests, qc_max_tests());
	let min_tests_passed = qc_min_tests_passed();

	QuickCheck { tests, max_tests, min_tests_passed, gen }
	}

	/// Set the random number generator to be used by QuickCheck.
	pub fn gen(self, gen: Gen) -> QuickCheck {
	QuickCheck { gen, ..self }
	}

	/// Set the number of tests to run.
	///
	/// This actually refers to the maximum number of passed tests that
	/// can occur. Namely, if a test causes a failure, future testing on that
	/// property stops. Additionally, if tests are discarded, there may be
	/// fewer than `tests` passed.
	pub fn tests(mut self, tests: u64) -> QuickCheck {
	self.tests = tests;
	self
	}

	/// Set the maximum number of tests to run.
	///
	/// The number of invocations of a property will never exceed this number.
	/// This is necessary to cap the number of tests because QuickCheck
	/// properties can discard tests.
	pub fn max_tests(mut self, max_tests: u64) -> QuickCheck {
	self.max_tests = max_tests;
	self
	}

	/// Set the minimum number of tests that needs to pass.
	///
	/// This actually refers to the minimum number of valid passed tests
	/// that needs to pass for the property to be considered successful.
	pub fn min_tests_passed(mut self, min_tests_passed: u64) -> QuickCheck {
	self.min_tests_passed = min_tests_passed;
	self
	}

	/// Tests a property and returns the result.
	///
	/// The result returned is either the number of tests passed or a witness
	/// of failure.
	///
	/// (If you're using Rust's unit testing infrastructure, then you'll
	/// want to use the `quickcheck` method, which will `panic!` on failure.)
	pub fn quicktest<A>(&mut self, f: A) -> Result<u64, TestResult>
	where
	A: Testable,
	{
	let mut n_tests_passed = 0;
	for _ in 0..self.max_tests {
	if n_tests_passed >= self.tests {
	break;
	}
	match f.result(&mut self.gen) {
	TestResult { status: Pass, .. } => n_tests_passed += 1,
	TestResult { status: Discard, .. } => continue,
	r @ TestResult { status: Fail, .. } => return Err(r),
	}
	}
	Ok(n_tests_passed)
	}

	/// Tests a property and calls `panic!` on failure.
	///
	/// The `panic!` message will include a (hopefully) minimal witness of
	/// failure.
	///
	/// It is appropriate to use this method with Rust's unit testing
	/// infrastructure.
	///
	/// Note that if the environment variable `RUST_LOG` is set to enable
	/// `info` level log messages for the `quickcheck` crate, then this will
	/// include output on how many QuickCheck tests were passed.
	///
	/// # Example
	///
	/// ```rust
	/// use quickcheck::QuickCheck;
	///
	/// fn prop_reverse_reverse() {
	/// fn revrev(xs: Vec<usize>) -> bool {
	/// let rev: Vec<_> = xs.clone().into_iter().rev().collect();
	/// let revrev: Vec<_> = rev.into_iter().rev().collect();
	/// xs == revrev
	/// }
	/// QuickCheck::new().quickcheck(revrev as fn(Vec<usize>) -> bool);
	/// }
	/// ```
	pub fn quickcheck<A>(&mut self, f: A)
	where
	A: Testable,
	{
	// Ignore log init failures, implying it has already been done.
	let _ = crate::env_logger_init();

	let n_tests_passed = match self.quicktest(f) {
	Ok(n_tests_passed) => n_tests_passed,
	Err(result) => panic!(result.failed_msg()),
	};

	if n_tests_passed >= self.min_tests_passed {
	info!("(Passed {} QuickCheck tests.)", n_tests_passed)
	} else {
	panic!(
	"(Unable to generate enough tests, {} not discarded.)",
	n_tests_passed
	)
	}
	}
	}

	/// Convenience function for running QuickCheck.
	///
	/// This is an alias for `QuickCheck::new().quickcheck(f)`.
	pub fn quickcheck<A: Testable>(f: A) {
	QuickCheck::new().quickcheck(f)
	}

	/// Describes the status of a single instance of a test.
	///
	/// All testable things must be capable of producing a `TestResult`.
	#[derive(Clone, Debug)]
	pub struct TestResult {
	status: Status,
	arguments: Vec<String>,
	err: Option<String>,
	}

	/// Whether a test has passed, failed or been discarded.
	#[derive(Clone, Debug)]
	enum Status {
	Pass,
	Fail,
	Discard,
	}

	impl TestResult {
	/// Produces a test result that indicates the current test has passed.
	pub fn passed() -> TestResult {
	TestResult::from_bool(true)
	}

	/// Produces a test result that indicates the current test has failed.
	pub fn failed() -> TestResult {
	TestResult::from_bool(false)
	}

	/// Produces a test result that indicates failure from a runtime error.
	pub fn error<S: Into<String>>(msg: S) -> TestResult {
	let mut r = TestResult::from_bool(false);
	r.err = Some(msg.into());
	r
	}

	/// Produces a test result that instructs `quickcheck` to ignore it.
	/// This is useful for restricting the domain of your properties.
	/// When a test is discarded, `quickcheck` will replace it with a
	/// fresh one (up to a certain limit).
	pub fn discard() -> TestResult {
	TestResult { status: Discard, arguments: vec![], err: None }
	}

	/// Converts a `bool` to a `TestResult`. A `true` value indicates that
	/// the test has passed and a `false` value indicates that the test
	/// has failed.
	pub fn from_bool(b: bool) -> TestResult {
	TestResult {
	status: if b { Pass } else { Fail },
	arguments: vec![],
	err: None,
	}
	}

	/// Tests if a "procedure" fails when executed. The test passes only if
	/// `f` generates a task failure during its execution.
	pub fn must_fail<T, F>(f: F) -> TestResult
	where
	F: FnOnce() -> T,
	F: 'static,
	T: 'static,
	{
	let f = panic::AssertUnwindSafe(f);
	TestResult::from_bool(panic::catch_unwind(f).is_err())
	}

	/// Returns `true` if and only if this test result describes a failing
	/// test.
	pub fn is_failure(&self) -> bool {
	match self.status {
	Fail => true,
	Pass \| Discard => false,
	}
	}

	/// Returns `true` if and only if this test result describes a failing
	/// test as a result of a run time error.
	pub fn is_error(&self) -> bool {
	self.is_failure() && self.err.is_some()
	}

	fn failed_msg(&self) -> String {
	match self.err {
	None => format!(
	"[quickcheck] TEST FAILED. Arguments: ({})",
	self.arguments.join(", ")
	),
	Some(ref err) => format!(
	"[quickcheck] TEST FAILED (runtime error). \
	Arguments: ({})\nError: {}",
	self.arguments.join(", "),
	err
	),
	}
	}
	}

	/// `Testable` describes types (e.g., a function) whose values can be
	/// tested.
	///
	/// Anything that can be tested must be capable of producing a `TestResult`
	/// given a random number generator. This is trivial for types like `bool`,
	/// which are just converted to either a passing or failing test result.
	///
	/// For functions, an implementation must generate random arguments
	/// and potentially shrink those arguments if they produce a failure.
	///
	/// It's unlikely that you'll have to implement this trait yourself.
	pub trait Testable: 'static {
	fn result(&self, _: &mut Gen) -> TestResult;
	}

	impl Testable for bool {
	fn result(&self, _: &mut Gen) -> TestResult {
	TestResult::from_bool(*self)
	}
	}

	impl Testable for () {
	fn result(&self, _: &mut Gen) -> TestResult {
	TestResult::passed()
	}
	}

	impl Testable for TestResult {
	fn result(&self, _: &mut Gen) -> TestResult {
	self.clone()
	}
	}

	impl<A, E> Testable for Result<A, E>
	where
	A: Testable,
	E: Debug + 'static,
	{
	fn result(&self, g: &mut Gen) -> TestResult {
	match *self {
	Ok(ref r) => r.result(g),
	Err(ref err) => TestResult::error(format!("{:?}", err)),
	}
	}
	}

	/// Return a vector of the debug formatting of each item in `args`
	fn debug_reprs(args: &[&dyn Debug]) -> Vec<String> {
	args.iter().map(\|x\| format!("{:?}", x)).collect()
	}

	macro_rules! testable_fn {
	($($name: ident),*) => {

	impl<T: Testable,
	$($name: Arbitrary + Debug),> Testable for fn($($name),) -> T {
	#[allow(non_snake_case)]
	fn result(&self, g: &mut Gen) -> TestResult {
	fn shrink_failure<T: Testable, $($name: Arbitrary + Debug),*>(
	g: &mut Gen,
	self_: fn($($name),*) -> T,
	a: ($($name,)*),
	) -> Option<TestResult> {
	for t in a.shrink() {
	let ($($name,)*) = t.clone();
	let mut r_new = safe(move \|\| {self_($($name),*)}).result(g);
	if r_new.is_failure() {
	{
	let ($(ref $name,)) : ($($name,)) = t;
	r_new.arguments = debug_reprs(&[$($name),*]);
	}

	// The shrunk value does witness a failure, so keep
	// trying to shrink it.
	let shrunk = shrink_failure(g, self_, t);

	// If we couldn't witness a failure on any shrunk value,
	// then return the failure we already have.
	return Some(shrunk.unwrap_or(r_new))
	}
	}
	None
	}

	let self_ = *self;
	let a: ($($name,)*) = Arbitrary::arbitrary(g);
	let ( $($name,)* ) = a.clone();
	let mut r = safe(move \|\| {self_($($name),*)}).result(g);

	{
	let ( $(ref $name,)* ) = a;
	r.arguments = debug_reprs(&[$($name),*]);
	}
	match r.status {
	Pass\|Discard => r,
	Fail => {
	shrink_failure(g, self_, a).unwrap_or(r)
	}
	}
	}
	}}}

	testable_fn!();
	testable_fn!(A);
	testable_fn!(A, B);
	testable_fn!(A, B, C);
	testable_fn!(A, B, C, D);
	testable_fn!(A, B, C, D, E);
	testable_fn!(A, B, C, D, E, F);
	testable_fn!(A, B, C, D, E, F, G);
	testable_fn!(A, B, C, D, E, F, G, H);

	fn safe<T, F>(fun: F) -> Result<T, String>
	where
	F: FnOnce() -> T,
	F: 'static,
	T: 'static,
	{
	panic::catch_unwind(panic::AssertUnwindSafe(fun)).map_err(\|any_err\| {
	// Extract common types of panic payload:
	// panic and assert produce &str or String
	if let Some(&s) = any_err.downcast_ref::<&str>() {
	s.to_owned()
	} else if let Some(s) = any_err.downcast_ref::<String>() {
	s.to_owned()
	} else {
	"UNABLE TO SHOW RESULT OF PANIC.".to_owned()
	}
	})
	}

	/// Convenient aliases.
	trait AShow: Arbitrary + Debug {}
	impl<A: Arbitrary + Debug> AShow for A {}

	#[cfg(test)]
	mod test {
	use crate::{Gen, QuickCheck};

	#[test]
	fn shrinking_regression_issue_126() {
	fn thetest(vals: Vec<bool>) -> bool {
	vals.iter().filter(\|&v\| *v).count() < 2
	}
	let failing_case = QuickCheck::new()
	.quicktest(thetest as fn(vals: Vec<bool>) -> bool)
	.unwrap_err();
	let expected_argument = format!("{:?}", [true, true]);
	assert_eq!(failing_case.arguments, vec![expected_argument]);
	}

	#[test]
	fn size_for_small_types_issue_143() {
	fn t(_: i8) -> bool {
	true
	}
	QuickCheck::new().gen(Gen::new(129)).quickcheck(t as fn(i8) -> bool);
	}

	#[test]
	fn regression_signed_shrinker_panic() {
	fn foo_can_shrink(v: i8) -> bool {
	let _ = crate::Arbitrary::shrink(&v).take(100).count();
	true
	}
	crate::quickcheck(foo_can_shrink as fn(i8) -> bool);
	}
	}