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proper.erl
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%%% Copyright 2010-2011 Manolis Papadakis <manopapad@gmail.com>,
%%% Eirini Arvaniti <eirinibob@gmail.com>
%%% and Kostis Sagonas <kostis@cs.ntua.gr>
%%%
%%% This file is part of PropEr.
%%%
%%% PropEr is free software: you can redistribute it and/or modify
%%% it under the terms of the GNU General Public License as published by
%%% the Free Software Foundation, either version 3 of the License, or
%%% (at your option) any later version.
%%%
%%% PropEr is distributed in the hope that it will be useful,
%%% but WITHOUT ANY WARRANTY; without even the implied warranty of
%%% MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
%%% GNU General Public License for more details.
%%%
%%% You should have received a copy of the GNU General Public License
%%% along with PropEr. If not, see <http://www.gnu.org/licenses/>.
%%% @copyright 2010-2011 Manolis Papadakis, Eirini Arvaniti and Kostis Sagonas
%%% @version {@version}
%%% @author Manolis Papadakis
%%% @doc This is the main PropEr module.
%%%
%%% == How to write properties ==
%%% The simplest properties that PropEr can test consist of a single boolean
%%% expression (or a statement block that returns a boolean), which is expected
%%% to evaluate to `true'. Thus, the test `true' always succeeds, while the test
%%% `false' always fails (the failure of a property may also be signified by
%%% throwing an exception, error or exit. More complex (and useful) properties
%%% can be written by wrapping such a boolean expression with one or more of the
%%% following wrappers:
%%%
%%% <dl>
%%% <dt>`?FORALL(<Xs>, <Xs_type>, <Prop>)'</dt>
%%% <dd>The `<Xs>' field can either be a single variable, a tuple of variables
%%% or a list of variables. The `<Xs_type>' field must then be a single type,
%%% a tuple of types of the same length as the tuple of variables or a list
%%% of types of the same length as the list of variables, respectively.
%%% Tuples and lists can be combined in any way, as long as `<Xs>' and
%%% `<Xs_type>' are compatible. Both PropEr-provided types, as listed in the
%%% {@link proper_types} module, and types declared in Erlang's built-in
%%% typesystem (we will refer to such types in as <em>native types</em>) may
%%% be used in the `<Xs_type>' field. The use of native types in `?FORALL's is
%%% subject to some limitations, as described in the documentation for the
%%% {@link proper_typeserver} module. All the variables inside `<Xs>' can
%%% (and should) be present as free variables inside the wrapped property
%%% `<Prop>'. When a `?FORALL' wrapper is encountered, a random instance of
%%% `<Xs_type>' is produced and each variable in `<Xs>' is replaced inside
%%% `<Prop>' by its corresponding instance.</dd>
%%% <dt>`?IMPLIES(<Precondition>, <Prop>)'</dt>
%%% <dd>This wrapper only makes sense when in the scope of at least one
%%% `?FORALL'. The `<Precondition>' field must be a boolean expression or a
%%% statement block that returns a boolean. If the precondition evaluates to
%%% `false' for the variable instances produced in the enclosing `?FORALL'
%%% wrappers, the test case is rejected (it doesn't count as a failing test
%%% case), and PropEr starts over with a new random test case. Also, in
%%% verbose mode, an `x' is printed on screen.</dd>
%%% <dt>`?WHENFAIL(<Action>, <Prop>)'</dt>
%%% <dd>The `<Action>' field should contain an expression or statement block
%%% that produces some side-effect (e.g. prints something to the screen).
%%% In case this test fails, `<Action>' will be executed. Note that the output
%%% of such actions is not affected by the verbosity setting of the main
%%% application.</dd>
%%% <dt>`?TRAPEXIT(<Prop>)'</dt>
%%% <dd>If the code inside `<Prop>' spawns and links to a process that dies
%%% abnormally, PropEr will catch the exit signal and treat it as a test
%%% failure, instead of crashing. `?TRAPEXIT' cannot contain any more
%%% wrappers.</dd>
%%% <dt>`?TIMEOUT(<Time_limit>, <Prop>)'</dt>
%%% <dd>Signifies that `<Prop>' should be considered failing if it takes more
%%% than `<Time_limit>' milliseconds to return. The purpose of this wrapper is
%%% to test code that may hang if something goes wrong. `?TIMEOUT' cannot
%%% contain any more wrappers.</dd>
%%% <dt>`conjunction(<SubProps>)'</dt>
%%% <dd>See the documentation for {@link conjunction/1}.</dd>
%%% <dt>`equals(<A>, <B>)'</dt>
%%% <dd>See the documentation for {@link equals/2}.</dd>
%%% </dl>
%%%
%%% There are also multiple wrappers that can be used to collect statistics on
%%% the distribution of test data:
%%%
%%% <ul>
%%% <li>{@link collect/2}</li>
%%% <li>{@link collect/3}</li>
%%% <li>{@link aggregate/2}</li>
%%% <li>{@link aggregate/3}</li>
%%% <li>{@link classify/3}</li>
%%% <li>{@link measure/3}</li>
%%% </ul>
%%%
%%% <span id="external-wrappers"></span>
%%% A property may also be wrapped with one or more of the following outer-level
%%% wrappers, which control the behaviour of the testing subsystem. If an
%%% outer-level wrapper appears more than once in a property, the innermost
%%% instance takes precedence.
%%%
%%% <ul>
%%% <li>{@link numtests/2}</li>
%%% <li>{@link fails/2}</li>
%%% <li>{@link on_output/2}</li>
%%% </ul>
%%%
%%% For some actual usage examples, see the code in the examples directory, or
%%% check out PropEr's site. The testing modules in the tests directory may also
%%% be of interest.
%%%
%%% == Program behaviour ==
%%% When running in verbose mode (this is the default), each sucessful test
%%% prints a '.' on screen. If a test fails, a '!' is printed, along with the
%%% failing test case (the instances of the types in every `?FORALL') and the
%%% cause of the failure, if it was not simply the falsification of the
%%% property.
%%% Then, unless the test was expected to fail, PropEr attempts to produce a
%%% minimal test case that fails the property in the same way. This process is
%%% called <em>shrinking</em>. During shrinking, a '.' is printed for each
%%% successful simplification of the failing test case. When PropEr reaches its
%%% shrinking limit or realizes that the instance cannot be shrunk further while
%%% still failing the test, it prints the minimal failing test case and failure
%%% reason and exits.
%%%
%%% The return value of PropEr can be one of the following:
%%%
%%% <ul>
%%% <li>`true': The property held for all valid produced inputs.</li>
%%% <li>`false': The property failed for some input.</li>
%%% <li>`{error, <Type_of_error>}': An error occured; see the {@section Errors}
%%% section for more information.</li>
%%% </ul>
%%%
%%% To test all properties exported from a module (a property is a 0-arity
%%% function whose name begins with `prop_'), you can use {@link module/1} or
%%% {@link module/2}. This returns a list of all failing properties, represented
%%% by MFAs. Testing progress is also printed on screen (unless quiet mode is
%%% active). The provided options are passed on to each property, except for
%%% `long_result', which controls the return value format of the `module'
%%% function itself.
%%%
%%% == Counterexamples ==
%%% A counterexample for a property is represented as a list of terms; each such
%%% term corresponds to the type in a `?FORALL'. The instances are provided in
%%% the same order as the `?FORALL' wrappers in the property, i.e. the instance
%%% at the head of the list corresponds to the outermost `?FORALL' etc.
%%% Instances generated inside a failing sub-property of a conjunction are
%%% marked with the sub-property's tag.
%%%
%%% The last (simplest) counterexample produced by PropEr during a (failing) run
%%% can be retrieved after testing has finished, by running
%%% {@link counterexample/0}. When testing a whole module, run
%%% {@link counterexamples/0} to get a counterexample for each failing property,
%%% as a list of `{mfa(), '{@type counterexample()}`}' tuples. To enable this
%%% functionality, some information has to remain in the process dictionary
%%% even after PropEr has returned. If, for some reason, you want to completely
%%% clean up the process dictionary of PropEr-produced entries, run
%%% {@link clean_garbage/0}.
%%%
%%% Counterexamples can also be retrieved by running PropEr in long-result mode,
%%% where counterexamples are returned as part of the return value.
%%% Specifically, when testing a single property under long-result mode
%%% (activated by supplying the option `long_result', or by calling
%%% {@link counterexample/1} or {@link counterexample/2} instead of
%%% {@link quickcheck/1} and {@link quickcheck/2} respectively), PropEr will
%%% return a counterexample in case of failure (instead of simply returning
%%% `false'). When testing a whole module under long-result mode (activated by
%%% supplying the option `long_result' to {@link module/2}), PropEr will return
%%% a list of `{mfa(), '{@type counterexample()}`}' tuples, one for each failing
%%% property.
%%%
%%% You can re-check a specific counterexample against the property that it
%%% previously falsified by running {@link check/2} or {@link check/3}. This
%%% will return one of the following (both in short- and long-result mode):
%%%
%%% <ul>
%%% <li>`true': The property now holds for this test case.</li>
%%% <li>`false': The test case still fails (although not necessarily for the
%%% same reason as before).</li>
%%% <li>`{error, <Type_of_error>}': An error occured - see the {@section Errors}
%%% section for more information.</li>
%%% </ul>
%%%
%%% Proper will not attempt to shrink the input in case it still fails the
%%% property. Unless silent mode is active, PropEr will also print a message on
%%% screen, describing the result of the re-checking. Note that PropEr can do
%%% very little to verify that the counterexample actually corresponds to the
%%% property that it is tested against.
%%%
%%% == Options ==
%%% Options can be provided as an extra argument to most testing functions (such
%%% as {@link quickcheck/1}). A single option can be written stand-alone, or
%%% multiple options can be provided in a list. When two settings conflict, the
%%% one that comes first in the list takes precedence. Settings given inside
%%% external wrappers to a property (see the {@section How to write properties}
%%% section) override any conflicting settings provided as options.
%%%
%%% The available options are:
%%%
%%% <dl>
%%% <dt>`quiet'</dt>
%%% <dd>Enables quiet mode - no output is printed on screen while PropEr is
%%% running.</dd>
%%% <dt>`verbose'</dt>
%%% <dd>Enables verbose mode - this is the default mode of operation.</dd>
%%% <dt>`{to_file, <IO_device>}'</dt>
%%% <dd>Redirects all of PropEr's output to `<IO_device>', which should be an
%%% IO device associated with a file opened for writing.</dd>
%%% <dt>`{on_output, <Output_function>}'</dt>
%%% <dd>PropEr will use the supplied function for all output printing. This
%%% function should accept two arguments in the style of `io:format/2'.<br/>
%%% CAUTION: The above output control options are incompatible with each
%%% other.</dd>
%%% <dt>`long_result'</dt>
%%% <dd>Enables long-result mode (see the {@section Counterexamples} section
%%% for details).</dd>
%%% <dt>`{numtests, <Positive_number>}' or simply `<Positive_number>'</dt>
%%% <dd>This is equivalent to the {@link numtests/1} property wrapper. Any
%%% {@link numtests/1} wrappers in the actual property will overwrite this
%%% setting.</dd>
%%% <dt>`{start_size, <Size>}'</dt>
%%% <dd>Specifies the initial value of the `size' parameter (default is 1), see
%%% the documentation of the {@link proper_types} module for details.</dd>
%%% <dt>`{max_size, <Size>}'</dt>
%%% <dd>Specifies the maximum value of the `size' parameter (default is 42), see
%%% the documentation of the {@link proper_types} module for details.</dd>
%%% <dt>`{max_shrinks, <Non_negative_number>}'</dt>
%%% <dd>Specifies the maximum number of times a failing test case should be
%%% shrunk before returning. Note that the shrinking may stop before so many
%%% shrinks are achieved if the shrinking subsystem deduces that it cannot
%%% shrink the failing test case further. Default is 500.</dd>
%%% <dt>`noshrink'</dt>
%%% <dd>Instructs PropEr to not attempt to shrink any failing test cases.</dd>
%%% <dt>`{constraint_tries, <Positive_number>}'</dt>
%%% <dd>Specifies the maximum number of tries before the generator subsystem
%%% gives up on producing an instance that satisfies a `?SUCHTHAT'
%%% constraint. Default is 50.</dd>
%%% <dt>`fails'</dt>
%%% <dd>This is equivalent to the {@link fails/1} property wrapper.</dd>
%%% <dt>`{spec_timeout, infinity | <Non_negative_number>}'</dt>
%%% <dd>When testing a spec, PropEr will consider an input to be failing if the
%%% function under test takes more than the specified amount of milliseconds
%%% to return for that input.</dd>
%%% <dt>`any_to_integer'</dt>
%%% <dd>All generated instances of the type {@link proper_types:any/0} will be
%%% integers. This is provided as a means to speed up the testing of specs,
%%% where `any()' is a commonly used type (see the {@section Spec testing}
%%% section for details).</dd>
%%% </dl>
%%%
%%% == Spec testing ==
%%% You can test the accuracy of an exported function's spec by running
%%% {@link check_spec/1} or {@link check_spec/2}.
%%% Under this mode of operation, PropEr will call the provided function with
%%% increasingly complex valid inputs (according to its spec) and test that no
%%% unexpected value is returned. If an input is found that violates the spec,
%%% it will be saved as a counterexample and PropEr will attempt to shrink it.
%%%
%%% You can test all exported functions of a module against their spec by
%%% running {@link check_specs/1} or {@link check_specs/2}.
%%%
%%% The use of `check_spec' is subject to the following usage rules:
%%%
%%% <ul>
%%% <li>Currently, PropEr can't test functions whose range contains a type
%%% that exhibits a certain kind of self-reference: it is (directly or
%%% indirectly) self-recursive and at least one recursion path contains only
%%% unions and type references. E.g. these types are acceptable:
%%% ``` -type a(T) :: T | {'bar',a(T)}.
%%% -type b() :: 42 | [c()].
%%% -type c() :: {'baz',b()}.'''
%%% while these are not:
%%% ``` -type a() :: 'foo' | b().
%%% -type b() :: c() | [integer()].
%%% -type c() :: 'bar' | a().
%%% -type d(T) :: T | d({'baz',T}).''' </li>
%%% <li>Throwing any exception or raising an `error:badarg' is considered
%%% normal behaviour. Currently, users cannot fine-tune this setting.</li>
%%% <li>Only the first clause of the function's spec is considered.</li>
%%% <li>The only spec constraints we accept are is_subtype' constraints whose
%%% first argument is a simple, non-'_' variable. It is not checked whether or
%%% not these variables actually appear in the spec. The second argument of an
%%% `is_subtype' constraint cannot contain any non-'_' variables. Multiple
%%% constraints for the same variable are not supported.</li>
%%% </ul>
%%%
%%% == Errors ==
%%% The following errors may be encountered during testing. The term provided
%%% for each error is the error type returned by proper:quickcheck in case such
%%% an error occurs. Normaly, a message is also printed on screen describing
%%% the error.
%%%
%%% <dl>
%%% <dt>`arity_limit'</dt>
%%% <dd>The random instance generation subsystem has failed to produce
%%% a function of the desired arity. Please recompile PropEr with a suitable
%%% value for `?MAX_ARITY' (defined in `proper_internal.hrl'). This error
%%% should only be encountered during normal operation.</dd>
%%% <dt>`cant_generate'</dt>
%%% <dd>The random instance generation subsystem has failed to
%%% produce an instance that satisfies some `?SUCHTHAT' constraint. You
%%% should either increase the `constraint_tries' limit, loosen the failing
%%% constraint, or make it non-strict. This error should only be encountered
%%% during normal operation.</dd>
%%% <dt>`cant_satisfy'</dt>
%%% <dd>All the tests were rejected because no produced test case
%%% would pass all `?IMPLIES' checks. You should loosen the failing `?IMPLIES'
%%% constraint(s). This error should only be encountered during normal
%%% operation.</dd>
%%% <dt>`non_boolean_result'</dt>
%%% <dd>The property code returned a non-boolean result. Please
%%% fix your property.</dd>
%%% <dt>`rejected'</dt>
%%% <dd>Only encountered during re-checking, the counterexample does not
%%% match the property, since the counterexample doesn't pass an `?IMPLIES'
%%% check.</dd>
%%% <dt>`too_many_instances'</dt>
%%% <dd>Only encountered during re-checking, the counterexample
%%% does not match the property, since the counterexample contains more
%%% instances than there are `?FORALL's in the property.</dd>
%%% <dt>`type_mismatch'</dt>
%%% <dd>The variables' and types' structures inside a `?FORALL' don't
%%% match. Please check your properties.</dd>
%%% <dt>`{typeserver, <SubError>}'</dt>
%%% <dd>The typeserver encountered an error. The `<SubError>' field contains
%%% specific information regarding the error.</dd>
%%% <dt>`{unexpected, <Result>}'</dt>
%%% <dd>A test returned an unexpected result during normal operation. If you
%%% ever get this error, it means that you have found a bug in PropEr
%%% - please send an error report to the maintainers and remember to include
%%% both the failing test case and the output of the program, if possible.
%%% </dd>
%%% <dt>`{unrecognized_option, <Option>}'</dt>
%%% <dd>`<Option>' is not an option that PropEr understands.</dd>
%%% </dl>
-module(proper).
-export([quickcheck/1, quickcheck/2, counterexample/1, counterexample/2,
check/2, check/3, module/1, module/2, check_spec/1, check_spec/2,
check_specs/1, check_specs/2]).
-export([numtests/2, fails/1, on_output/2, conjunction/1]).
-export([collect/2, collect/3, aggregate/2, aggregate/3, classify/3, measure/3,
with_title/1, equals/2]).
-export([counterexample/0, counterexamples/0]).
-export([clean_garbage/0, global_state_erase/0]).
-export([get_size/1, global_state_init_size/1,
global_state_init_size_seed/2,report_error/2]).
-export([pure_check/1, pure_check/2]).
-export([forall/2, implies/2, whenfail/2, trapexit/1, timeout/2]).
-export_type([test/0, outer_test/0, counterexample/0, exception/0]).
-include("proper_internal.hrl").
%%-----------------------------------------------------------------------------
%% Macros
%%-----------------------------------------------------------------------------
-define(MISMATCH_MSG, "Error: The input doesn't correspond to this property: ").
%%-----------------------------------------------------------------------------
%% Test types
%%-----------------------------------------------------------------------------
-type imm_testcase() :: [imm_input()].
-type imm_input() :: proper_gen:imm_instance()
| {'$conjunction',sub_imm_testcases()}.
-type sub_imm_testcases() :: [{tag(),imm_testcase()}].
-type imm_counterexample() :: [imm_clean_input()].
-type imm_clean_input() :: proper_gen:instance()
| {'$conjunction',sub_imm_counterexamples()}.
-type sub_imm_counterexamples() :: [{tag(),imm_counterexample()}].
-type counterexample() :: [clean_input()].
%% @alias
-type clean_input() :: proper_gen:instance() | sub_counterexamples().
%% @alias
-type sub_counterexamples() :: [{tag(),counterexample()}].
-type sample() :: [term()].
-type freq_sample() :: [{term(),frequency()}].
-type side_effects_fun() :: fun(() -> 'ok').
-type fail_actions() :: [side_effects_fun()].
-type output_fun() :: fun((string(),[term()]) -> 'ok').
%% A fun to be used by PropEr for output printing. Such a fun should follow the
%% conventions of `io:format/2'.
-type tag() :: atom().
-type title() :: atom() | string().
-type stats_printer() :: fun((sample()) -> 'ok')
| fun((sample(),output_fun()) -> 'ok').
%% A stats-printing function that can be passed to some of the statistics
%% collection functions, to be used instead of the predefined stats-printer.
%% Such a function will be called at the end of testing (in case no test fails)
%% with a sorted list of collected terms. A commonly used stats-printer is
%% `with_title/1'.
-type numeric_stat() :: number() | 'undefined'.
-type numeric_stats() :: {numeric_stat(),numeric_stat(),numeric_stat()}.
-type time_period() :: non_neg_integer().
%% TODO: This should be opaque.
%% @type outer_test(). A testable property that has optionally been wrapped with
%% one or more <a href="#external-wrappers">external wrappers</a>.
-type outer_test() :: test()
| numtests_clause()
| fails_clause()
| on_output_clause().
%% TODO: This should be opaque.
%% TODO: Should the tags be of the form '$...'?
%% @type test(). A testable property that has not been wrapped with an
%% <a href="#external-wrappers">external wrapper</a>.
-type test() :: boolean()
| forall_clause()
| conjunction_clause()
| implies_clause()
| sample_clause()
| whenfail_clause()
| trapexit_clause()
| timeout_clause().
%%| always_clause()
%%| sometimes_clause()
-type delayed_test() :: fun(() -> test()).
-type dependent_test() :: fun((proper_gen:instance()) -> test()).
-type lazy_test() :: delayed_test() | dependent_test().
-type raw_test_kind() :: 'test' | 'spec'.
-type raw_test() :: {'test',test()} | {'spec',mfa()}.
-type stripped_test() :: boolean()
| {proper_types:type(), dependent_test()}
| [{tag(),test()}].
-type numtests_clause() :: {'numtests', pos_integer(), outer_test()}.
-type fails_clause() :: {'fails', outer_test()}.
-type on_output_clause() :: {'on_output', output_fun(), outer_test()}.
-type forall_clause() :: {'forall', proper_types:raw_type(), dependent_test()}.
-type conjunction_clause() :: {'conjunction', [{tag(),test()}]}.
-type implies_clause() :: {'implies', boolean(), delayed_test()}.
-type sample_clause() :: {'sample', sample(), stats_printer(), test()}.
-type whenfail_clause() :: {'whenfail', side_effects_fun(), delayed_test()}.
-type trapexit_clause() :: {'trapexit', fun(() -> boolean())}.
-type timeout_clause() :: {'timeout', time_period(), fun(() -> boolean())}.
%%-type always_clause() :: {'always', pos_integer(), delayed_test()}.
%%-type sometimes_clause() :: {'sometimes', pos_integer(), delayed_test()}.
%%-----------------------------------------------------------------------------
%% Options and Context types
%%-----------------------------------------------------------------------------
%% TODO: Rename this to 'options()'?
-type user_opt() :: 'quiet'
| 'verbose'
| {'to_file',file:io_device()}
| {'on_output',output_fun()}
| 'long_result'
| {'numtests', pos_integer()}
| pos_integer()
| {'start_size',size()}
| {'max_size', size()}
| {'max_shrinks',non_neg_integer()}
| 'noshrink'
| {'constraint_tries',pos_integer()}
| 'fails'
| 'any_to_integer'
| {'spec_timeout',timeout()}.
-type user_opts() :: [user_opt()] | user_opt().
-record(opts, {output_fun = fun io:format/2 :: output_fun(),
long_result = false :: boolean(),
numtests = 100 :: pos_integer(),
start_size = 1 :: size(),
seed :: seed(),
max_size = 42 :: size(),
max_shrinks = 500 :: non_neg_integer(),
noshrink = false :: boolean(),
constraint_tries = 50 :: pos_integer(),
expect_fail = false :: boolean(),
any_type :: {'type',
proper_types:type()},
spec_timeout = infinity :: timeout()}).
-type opts() :: #opts{}.
-record(ctx, {mode = new :: 'new' | 'try_shrunk' | 'try_cexm',
bound = [] :: imm_testcase() | counterexample(),
actions = [] :: fail_actions(),
samples = [] :: [sample()],
printers = [] :: [stats_printer()]}).
-type ctx() :: #ctx{}.
%%-----------------------------------------------------------------------------
%% Result types
%%-----------------------------------------------------------------------------
-record(pass, {reason :: pass_reason(),
samples :: [sample()],
printers :: [stats_printer()],
performed :: pos_integer()}).
-record(fail, {reason :: fail_reason(),
bound :: imm_testcase() | counterexample(),
actions :: fail_actions(),
performed :: pos_integer()}).
%% @alias
-type error() :: {'error', error_reason()}.
-type pass_reason() :: 'true_prop' | 'didnt_crash'.
-type fail_reason() :: 'false_prop' | 'time_out' | {'trapped',exc_reason()}
| exception() | {'sub_props',[{tag(),fail_reason()},...]}.
%% @private_type
-type exception() :: {'exception',exc_kind(),exc_reason(),stacktrace()}.
-type exc_kind() :: 'throw' | 'error' | 'exit'.
-type exc_reason() :: term().
-type stacktrace() :: [call_record()].
-ifdef(OLD_STACKTRACE_FORMAT).
-type call_record() :: {mod_name(),fun_name(),arity() | list()}.
-else.
-type call_record() :: {mod_name(),fun_name(),arity() | list(),location()}.
-type location() :: [{atom(),term()}].
-endif.
-type error_reason() :: 'arity_limit' | 'cant_generate' | 'cant_satisfy'
| 'non_boolean_result' | 'rejected' | 'too_many_instances'
| 'type_mismatch' | 'wrong_type' | {'typeserver',term()}
| {'unexpected',any()} | {'unrecognized_option',term()}.
-type run_result() :: #pass{performed :: 'undefined'}
| #fail{performed :: 'undefined'}
| error().
-type imm_result() :: #pass{reason :: 'undefined'} | #fail{} | error().
-type long_result() :: 'true' | counterexample() | error().
-type short_result() :: boolean() | error().
-type result() :: long_result() | short_result().
-type long_module_result() :: [{mfa(),counterexample()}] | error().
-type short_module_result() :: [mfa()] | error().
-type module_result() :: long_module_result() | short_module_result().
-type shrinking_result() :: {non_neg_integer(),imm_testcase()}.
%%-----------------------------------------------------------------------------
%% State handling functions
%%-----------------------------------------------------------------------------
-spec grow_size(opts()) -> 'ok'.
grow_size(#opts{max_size = MaxSize} = Opts) ->
Size = get('$size'),
case Size < MaxSize of
true ->
case get('$left') of
0 ->
put('$size', Size + 1),
case tests_at_size(Size + 1, Opts) of
0 -> grow_size(Opts);
N -> put('$left', N - 1), ok
end;
Left ->
put('$left', Left - 1),
ok
end;
false ->
ok
end.
-spec tests_at_size(size(), opts()) -> non_neg_integer().
tests_at_size(Size, #opts{numtests = NumTests, start_size = StartSize,
max_size = MaxSize}) ->
SizesToTest = MaxSize - StartSize + 1,
case NumTests >= SizesToTest of
true ->
TotalOverflow = NumTests rem SizesToTest,
Overflow = case MaxSize - Size < TotalOverflow of
true -> 1;
false -> 0
end,
NumTests div SizesToTest + Overflow;
false ->
EverySoManySizes = SizesToTest div NumTests,
case (Size - StartSize) rem EverySoManySizes of
0 -> 1;
_ -> 0
end
end.
%% @private
-spec get_size(proper_types:type()) -> size() | 'undefined'.
get_size(Type) ->
case get('$size') of
undefined ->
undefined;
Size ->
case proper_types:find_prop(size_transform, Type) of
{ok,Transform} -> Transform(Size);
error -> Size
end
end.
%% @private
-spec global_state_init_size(size()) -> 'ok'.
global_state_init_size(Size) ->
global_state_init(#opts{start_size = Size}).
%% @private
-spec global_state_init_size_seed(size(), seed()) -> 'ok'.
global_state_init_size_seed(Size, Seed) ->
global_state_init(#opts{start_size = Size, seed = Seed}).
-spec global_state_init(opts()) -> 'ok'.
global_state_init(#opts{start_size = StartSize, constraint_tries = CTries,
any_type = AnyType, seed = Seed} = Opts) ->
clean_garbage(),
put('$size', StartSize - 1),
put('$left', 0),
grow_size(Opts),
put('$constraint_tries', CTries),
put('$any_type',AnyType),
S = case Seed of
undefined ->
now();
_ ->
Seed
end,
proper_arith:rand_start(S),
proper_typeserver:start(),
ok.
-spec global_state_reset(opts()) -> 'ok'.
global_state_reset(#opts{start_size = StartSize} = Opts) ->
clean_garbage(),
put('$size', StartSize - 1),
put('$left', 0),
grow_size(Opts).
%% @private
-spec global_state_erase() -> 'ok'.
global_state_erase() ->
proper_typeserver:stop(),
proper_arith:rand_stop(),
erase('$any_type'),
erase('$constraint_tries'),
erase('$left'),
erase('$size'),
erase('$parameters'),
ok.
%% @private
-spec spawn_link_migrate(fun(() -> _)) -> pid().
spawn_link_migrate(ActualFun) ->
PDictStuff = get(),
Fun = fun() ->
lists:foreach(fun({K,V}) -> put(K,V) end, PDictStuff),
proper_arith:rand_reseed(),
ActualFun()
end,
spawn_link(Fun).
-spec save_counterexample(counterexample()) -> 'ok'.
save_counterexample(CExm) ->
put('$counterexample', CExm),
ok.
%% @doc Retrieves the last (simplest) counterexample produced by PropEr during
%% the most recent testing run.
-spec counterexample() -> counterexample() | 'undefined'.
counterexample() ->
get('$counterexample').
-spec save_counterexamples([{mfa(),counterexample()}]) -> 'ok'.
save_counterexamples(CExms) ->
put('$counterexamples', CExms),
ok.
%% @doc Returns a counterexample for each failing property of the most recent
%% module testing run.
-spec counterexamples() -> [{mfa(),counterexample()}] | 'undefined'.
counterexamples() ->
get('$counterexamples').
%% @doc Cleans up the process dictionary of all PropEr-produced entries.
-spec clean_garbage() -> 'ok'.
clean_garbage() ->
erase('$counterexample'),
erase('$counterexamples'),
ok.
%%-----------------------------------------------------------------------------
%% Public interface functions
%%-----------------------------------------------------------------------------
%% @doc Runs PropEr on the property `OuterTest'.
-spec quickcheck(outer_test()) -> result().
quickcheck(OuterTest) ->
quickcheck(OuterTest, []).
%% @doc Same as {@link quickcheck/1}, but also accepts a list of options.
-spec quickcheck(outer_test(), user_opts()) -> result().
quickcheck(OuterTest, UserOpts) ->
try parse_opts(UserOpts) of
ImmOpts ->
{Test,Opts} = peel_test(OuterTest, ImmOpts),
test({test,Test}, Opts)
catch
throw:{unrecognized_option,_UserOpt} = Reason ->
report_error(Reason, fun io:format/2),
{error, Reason}
end.
%% @equiv quickcheck(OuterTest, [long_result])
-spec counterexample(outer_test()) -> long_result().
counterexample(OuterTest) ->
counterexample(OuterTest, []).
%% @doc Same as {@link counterexample/1}, but also accepts a list of options.
-spec counterexample(outer_test(), user_opts()) -> long_result().
counterexample(OuterTest, UserOpts) ->
quickcheck(OuterTest, add_user_opt(long_result,UserOpts)).
%% @private
%% @doc Runs PropEr in pure mode. Under this mode, PropEr will perform no I/O
%% and will not access the caller's process dictionary in any way. Please note
%% that PropEr will not actually run as a pure function under this mode.
-spec pure_check(outer_test()) -> result().
pure_check(OuterTest) ->
pure_check(OuterTest, []).
%% @private
%% @doc Same as {@link pure_check/2}, but also accepts a list of options.
-spec pure_check(outer_test(), user_opts()) -> result().
pure_check(OuterTest, ImmUserOpts) ->
Parent = self(),
UserOpts = add_user_opt(quiet, ImmUserOpts),
spawn_link(fun() -> Parent ! {result,quickcheck(OuterTest,UserOpts)} end),
receive
{result,Result} -> Result
end.
%% @doc Tests the accuracy of an exported function's spec.
-spec check_spec(mfa()) -> result().
check_spec(MFA) ->
check_spec(MFA, []).
%% @doc Same as {@link check_spec/1}, but also accepts a list of options.
-spec check_spec(mfa(), user_opts()) -> result().
check_spec(MFA, UserOpts) ->
try parse_opts(UserOpts) of
Opts ->
test({spec,MFA}, Opts)
catch
throw:{unrecognized_option,_UserOpt} = Reason ->
report_error(Reason, fun io:format/2),
{error, Reason}
end.
%% @doc Re-checks a specific counterexample `CExm' against the property
%% `OuterTest' that it previously falsified.
-spec check(outer_test(), counterexample()) -> short_result().
check(OuterTest, CExm) ->
check(OuterTest, CExm, []).
%% @doc Same as {@link check/2}, but also accepts a list of options.
-spec check(outer_test(), counterexample(), user_opts()) -> short_result().
check(OuterTest, CExm, UserOpts) ->
try parse_opts(UserOpts) of
ImmOpts ->
{Test,Opts} = peel_test(OuterTest, ImmOpts),
retry(Test, CExm, Opts)
catch
throw:{unrecognized_option,_UserOpt} = Reason ->
report_error(Reason, fun io:format/2),
{error, Reason}
end.
%% @doc Tests all properties (i.e., all 0-arity functions whose name begins with
%% `prop_') exported from module `Mod'.
-spec module(mod_name()) -> module_result().
module(Mod) ->
module(Mod, []).
%% @doc Same as {@link module/1}, but also accepts a list of options.
-spec module(mod_name(), user_opts()) -> module_result().
module(Mod, UserOpts) ->
multi_test_prep(Mod, test, UserOpts).
%% @doc Tests all exported, `-spec'ed functions of a module `Mod' against their
%% spec.
-spec check_specs(mod_name()) -> module_result().
check_specs(Mod) ->
check_specs(Mod, []).
%% @doc Same as {@link check_specs/1}, but also accepts a list of options.
-spec check_specs(mod_name(), user_opts()) -> module_result().
check_specs(Mod, UserOpts) ->
multi_test_prep(Mod, spec, UserOpts).
-spec multi_test_prep(mod_name(), raw_test_kind(), user_opts()) ->
module_result().
multi_test_prep(Mod, Kind, UserOpts) ->
try parse_opts(UserOpts) of
Opts ->
multi_test(Mod, Kind, Opts)
catch
throw:{unrecognized_option,_UserOpt} = Reason ->
report_error(Reason, fun io:format/2),
{error, Reason}
end.
%%-----------------------------------------------------------------------------
%% Options parsing functions
%%-----------------------------------------------------------------------------
-spec add_user_opt(user_opt(), user_opts()) -> [user_opt(),...].
add_user_opt(NewUserOpt, UserOptsList) when is_list(UserOptsList) ->
[NewUserOpt | UserOptsList];
add_user_opt(NewUserOpt, SingleUserOpt) ->
add_user_opt(NewUserOpt, [SingleUserOpt]).
-spec parse_opts(user_opts()) -> opts().
parse_opts(UserOptsList) when is_list(UserOptsList) ->
parse_opts(lists:reverse(UserOptsList), #opts{});
parse_opts(SingleUserOpt) ->
parse_opts([SingleUserOpt]).
-spec parse_opts([user_opt()], opts()) -> opts().
parse_opts([], Opts) ->
Opts;
parse_opts([UserOpt | Rest], Opts) ->
parse_opts(Rest, parse_opt(UserOpt,Opts)).
-spec parse_opt(user_opt(), opts()) -> opts().
parse_opt(UserOpt, Opts) ->
case UserOpt of
quiet -> Opts#opts{output_fun = fun(_,_) -> ok end};
verbose -> Opts#opts{output_fun = fun io:format/2};
{to_file,IoDev} -> Opts#opts{output_fun =
fun(S,F) -> io:format(IoDev, S, F) end
};
{on_output,Print} -> Opts#opts{output_fun = Print};
long_result -> Opts#opts{long_result = true};
{numtests,N} -> Opts#opts{numtests = N};
N when is_integer(N) -> Opts#opts{numtests = N};
{start_size,Size} -> Opts#opts{start_size = Size};
{max_size,Size} -> Opts#opts{max_size = Size};
{max_shrinks,N} -> Opts#opts{max_shrinks = N};
noshrink -> Opts#opts{noshrink = true};
{constraint_tries,N} -> Opts#opts{constraint_tries = N};
fails -> Opts#opts{expect_fail = true};
any_to_integer -> Opts#opts{any_type =
{type,proper_types:integer()}
};
{spec_timeout,N} -> Opts#opts{spec_timeout = N};
_ -> throw({unrecognized_option,UserOpt})
end.
-spec peel_test(outer_test(), opts()) -> {test(),opts()}.
peel_test({numtests,N,OuterTest}, Opts) ->
peel_test(OuterTest, Opts#opts{numtests = N});
peel_test({fails,OuterTest}, Opts) ->
peel_test(OuterTest, Opts#opts{expect_fail = true});
peel_test({on_output,Print,OuterTest}, Opts) ->
peel_test(OuterTest, Opts#opts{output_fun = Print});
peel_test(Test, Opts) ->
{Test, Opts}.
%%-----------------------------------------------------------------------------
%% Test declaration functions
%%-----------------------------------------------------------------------------
%% TODO: All of these should have a test() or outer_test() return type.
%% @doc Specifies the number `N' of tests to run when testing the property
%% `Test'. Default is 100.
%% @spec numtests(pos_integer(), outer_test()) -> outer_test()
-spec numtests(pos_integer(), outer_test()) -> numtests_clause().
numtests(N, Test) ->
{numtests, N, Test}.
%% @doc Specifies that we expect the property `Test' to fail for some input. The
%% property will be considered failing if it passes all the tests.
%% @spec fails(outer_test()) -> outer_test()
-spec fails(outer_test()) -> fails_clause().
fails(Test) ->
{fails, Test}.
%% @doc Specifies an output function `Print' to be used by PropEr for all output
%% printing during the testing of property `Test'. This wrapper is equivalent to
%% the `on_output' option.
%% @spec on_output(output_fun(), outer_test()) -> outer_test()
-spec on_output(output_fun(), outer_test()) -> on_output_clause().
on_output(Print, Test) ->
{on_output, Print, Test}.
%% @private
-spec forall(proper_types:raw_type(), dependent_test()) -> forall_clause().
forall(RawType, DTest) ->
{forall, RawType, DTest}.
%% @doc Returns a property that is true only if all of the sub-properties
%% `SubProps' are true. Each sub-property should be tagged with a distinct atom.
%% If this property fails, each failing sub-property will be reported and saved
%% inside the counterexample along with its tag.
%% @spec conjunction([{tag(),test()}]) -> test()
-spec conjunction([{tag(),test()}]) -> conjunction_clause().
conjunction(SubProps) ->
{conjunction, SubProps}.
%% @private
-spec implies(boolean(), delayed_test()) -> implies_clause().
implies(Pre, DTest) ->
{implies, Pre, DTest}.
%% @doc Specifies that test cases produced by this property should be
%% categorized under the term `Category'. This field can be an expression or
%% statement block that evaluates to any term. All produced categories are
%% printed at the end of testing (in case no test fails) along with the
%% percentage of test cases belonging to each category. Multiple `collect'
%% wrappers are allowed in a single property, in which case the percentages for
%% each `collect' wrapper are printed separately.
%% @spec collect(term(), test()) -> test()
-spec collect(term(), test()) -> sample_clause().
collect(Category, Test) ->
collect(with_title(""), Category, Test).
%% @doc Same as {@link collect/2}, but also accepts a fun `Printer' to be used
%% as the stats printer.
%% @spec collect(stats_printer(), term(), test()) -> test()
-spec collect(stats_printer(), term(), test()) -> sample_clause().
collect(Printer, Category, Test) ->
aggregate(Printer, [Category], Test).
%% @doc Same as {@link collect/2}, but accepts a list of categories under which
%% to classify the produced test case.
%% @spec aggregate(sample(), test()) -> test()
-spec aggregate(sample(), test()) -> sample_clause().
aggregate(Sample, Test) ->
aggregate(with_title(""), Sample, Test).
%% @doc Same as {@link collect/3}, but accepts a list of categories under which
%% to classify the produced test case.
%% @spec aggregate(stats_printer(), sample(), test()) -> test()
-spec aggregate(stats_printer(), sample(), test()) -> sample_clause().
aggregate(Printer, Sample, Test) ->
{sample, Sample, Printer, Test}.
%% @doc Same as {@link collect/2}, but can accept both a single category and a
%% list of categories. `Count' is a boolean flag: when `false', the particular
%% test case will not be counted.
%% @spec classify(Count::boolean(), term() | sample(), test()) -> test()
-spec classify(boolean(), term() | sample(), test()) -> sample_clause().
classify(false, _TermOrSample, Test) ->
aggregate([], Test);
classify(true, Sample, Test) when is_list(Sample) ->
aggregate(Sample, Test);
classify(true, Term, Test) ->
collect(Term, Test).
%% @doc A function that collects numeric statistics on the produced instances.
%% The number (or numbers) provided are collected and some statistics over the
%% collected sample are printed at the end of testing (in case no test fails),
%% prepended with `Title', which should be an atom or string.
%% @spec measure(title(), number() | [number()], test()) -> test()
-spec measure(title(), number() | [number()], test()) -> sample_clause().
measure(Title, Sample, Test) when is_number(Sample) ->
measure(Title, [Sample], Test);
measure(Title, Sample, Test) when is_list(Sample) ->
aggregate(numeric_with_title(Title), Sample, Test).
%% @private
-spec whenfail(side_effects_fun(), delayed_test()) -> whenfail_clause().
whenfail(Action, DTest) ->
{whenfail, Action, DTest}.
%% @private
-spec trapexit(fun(() -> boolean())) -> trapexit_clause().
trapexit(DTest) ->
{trapexit, DTest}.
%% @private
-spec timeout(time_period(), fun(() -> boolean())) -> timeout_clause().
timeout(Limit, DTest) ->
{timeout, Limit, DTest}.
%% @doc A custom property that evaluates to `true' only if `A =:= B', else
%% evaluates to `false' and prints "`A =/= B'" on the screen.
%% @spec equals(term(), term()) -> test()
-spec equals(term(), term()) -> whenfail_clause().
equals(A, B) ->
?WHENFAIL(io:format("~w =/= ~w~n",[A,B]), A =:= B).
%%-----------------------------------------------------------------------------
%% Bulk testing functions
%%-----------------------------------------------------------------------------
-spec test(raw_test(), opts()) -> result().
test(RawTest, Opts) ->
global_state_init(Opts),
Result = inner_test(RawTest, Opts),
global_state_erase(),
Result.
-spec inner_test(raw_test(), opts()) -> result().
inner_test(RawTest, #opts{numtests = NumTests, long_result = ReturnLong,