Predicate

Predicate

A Predicate is part of the new matcher API that provides assertions to expectations.

public struct Predicate<T>

Given a code snippet:

expect(1).to(equal(2)) ^^^^^^^^ Called a "matcher"

A matcher consists of two parts a constructor function and the Predicate. The term Predicate is used as a separate name from Matcher to help transition custom matchers to the new Nimble matcher API.

The Predicate provide the heavy lifting on how to assert against a given value. Internally, predicates are simple wrappers around closures to provide static type information and allow composition and wrapping of existing behaviors.

Inheritance

Matcher, Matcher, Matcher, Matcher

Initializers

init(_:)

Constructs a predicate that knows how take a given value

public init(_ matcher: @escaping (Expression<T>) throws -> PredicateResult)

init(_:)

Constructs a predicate that knows how take a given value

public init(_ matcher: @escaping (Expression<T>) throws -> PredicateResult)

Properties

requireNonNil

Returns a new Predicate based on the current one that always fails if nil is given as the actual value.

var requireNonNil: Predicate<T>

This replaces NonNilMatcherFunc.

requireNonNil

Returns a new Predicate based on the current one that always fails if nil is given as the actual value.

var requireNonNil: Predicate<T>

This replaces NonNilMatcherFunc.

Methods

satisfies(_:)

Uses a predicate on a given value to see if it passes the predicate.

public func satisfies(_ expression: Expression<T>) throws -> PredicateResult

@param expression The value to run the predicate's logic against @returns A predicate result indicate passing or failing and an associated error message.

define(matcher:)

Like Predicate() constructor, but automatically guard against nil (actual) values

public static func define(matcher: @escaping (Expression<T>) throws -> PredicateResult) -> Predicate<T>

define(_:matcher:)

Defines a predicate with a default message that can be returned in the closure Also ensures the predicate's actual value cannot pass with nil given.

public static func define(_ msg: String, matcher: @escaping (Expression<T>, ExpectationMessage) throws -> PredicateResult) -> Predicate<T>

defineNilable(_:matcher:)

Defines a predicate with a default message that can be returned in the closure Unlike define, this allows nil values to succeed if the given closure chooses to.

public static func defineNilable(_ msg: String, matcher: @escaping (Expression<T>, ExpectationMessage) throws -> PredicateResult) -> Predicate<T>

simple(_:matcher:)

Provides a simple predicate definition that provides no control over the predefined error message.

public static func simple(_ msg: String, matcher: @escaping (Expression<T>) throws -> PredicateStatus) -> Predicate<T>

Also ensures the predicate's actual value cannot pass with nil given.

simpleNilable(_:matcher:)

Provides a simple predicate definition that provides no control over the predefined error message.

public static func simpleNilable(_ msg: String, matcher: @escaping (Expression<T>) throws -> PredicateStatus) -> Predicate<T>

Unlike simple, this allows nil values to succeed if the given closure chooses to.

fromDeprecatedFullClosure(_:)

Compatibility layer for old Matcher API, deprecated

public static func fromDeprecatedFullClosure(_ matcher: @escaping (Expression<T>, FailureMessage, Bool) throws -> Bool) -> Predicate

fromDeprecatedClosure(_:)

Compatibility layer for old Matcher API, deprecated. Emulates the MatcherFunc API

public static func fromDeprecatedClosure(_ matcher: @escaping (Expression<T>, FailureMessage) throws -> Bool) -> Predicate

fromDeprecatedMatcher(_:)

Compatibility layer for old Matcher API, deprecated. Same as calling .predicate on a MatcherFunc or NonNilMatcherFunc type.

public static func fromDeprecatedMatcher<M>(_ matcher: M) -> Predicate where M: Matcher, M.ValueType == T

matches(_:failureMessage:)

Deprecated Matcher API, use satisfies(:​) instead

public func matches(_ actualExpression: Expression<T>, failureMessage: FailureMessage) throws -> Bool

doesNotMatch(_:failureMessage:)

Deprecated Matcher API, use satisfies(:​) instead

public func doesNotMatch(_ actualExpression: Expression<T>, failureMessage: FailureMessage) throws -> Bool

satisfies(_:)

Uses a predicate on a given value to see if it passes the predicate.

public func satisfies(_ expression: Expression<T>) throws -> PredicateResult

@param expression The value to run the predicate's logic against @returns A predicate result indicate passing or failing and an associated error message.

define(matcher:)

Like Predicate() constructor, but automatically guard against nil (actual) values

public static func define(matcher: @escaping (Expression<T>) throws -> PredicateResult) -> Predicate<T>

define(_:matcher:)

Defines a predicate with a default message that can be returned in the closure Also ensures the predicate's actual value cannot pass with nil given.

public static func define(_ msg: String, matcher: @escaping (Expression<T>, ExpectationMessage) throws -> PredicateResult) -> Predicate<T>

defineNilable(_:matcher:)

Defines a predicate with a default message that can be returned in the closure Unlike define, this allows nil values to succeed if the given closure chooses to.

public static func defineNilable(_ msg: String, matcher: @escaping (Expression<T>, ExpectationMessage) throws -> PredicateResult) -> Predicate<T>

simple(_:matcher:)

Provides a simple predicate definition that provides no control over the predefined error message.

public static func simple(_ msg: String, matcher: @escaping (Expression<T>) throws -> PredicateStatus) -> Predicate<T>

Also ensures the predicate's actual value cannot pass with nil given.

simpleNilable(_:matcher:)

Provides a simple predicate definition that provides no control over the predefined error message.

public static func simpleNilable(_ msg: String, matcher: @escaping (Expression<T>) throws -> PredicateStatus) -> Predicate<T>

Unlike simple, this allows nil values to succeed if the given closure chooses to.

fromDeprecatedFullClosure(_:)

Compatibility layer for old Matcher API, deprecated

public static func fromDeprecatedFullClosure(_ matcher: @escaping (Expression<T>, FailureMessage, Bool) throws -> Bool) -> Predicate

fromDeprecatedClosure(_:)

Compatibility layer for old Matcher API, deprecated. Emulates the MatcherFunc API

public static func fromDeprecatedClosure(_ matcher: @escaping (Expression<T>, FailureMessage) throws -> Bool) -> Predicate

fromDeprecatedMatcher(_:)

Compatibility layer for old Matcher API, deprecated. Same as calling .predicate on a MatcherFunc or NonNilMatcherFunc type.

public static func fromDeprecatedMatcher<M>(_ matcher: M) -> Predicate where M: Matcher, M.ValueType == T

matches(_:failureMessage:)

Deprecated Matcher API, use satisfies(:​) instead

public func matches(_ actualExpression: Expression<T>, failureMessage: FailureMessage) throws -> Bool

doesNotMatch(_:failureMessage:)

Deprecated Matcher API, use satisfies(:​) instead

public func doesNotMatch(_ actualExpression: Expression<T>, failureMessage: FailureMessage) throws -> Bool