TripleEqualsSupport
Class used via an implicit conversion to enable two objects to be compared with
=== and !== with a Boolean result and an enforced type constraint between
two object types.
Class used via an implicit conversion to enable two objects to be compared with
=== and !== with a Boolean result and an enforced type constraint between
two object types. For example:
assert(a === b) assert(c !== d)
You can also check numeric values against another with a tolerance. Here are some examples:
assert(a === (2.0 +- 0.1)) assert(c !== (2.0 +- 0.1))
Class used via an implicit conversion to enable any two objects to be compared with
=== and !== with a Boolean result and no enforced type constraint between
two object types.
Class used via an implicit conversion to enable any two objects to be compared with
=== and !== with a Boolean result and no enforced type constraint between
two object types. For example:
assert(a === b) assert(c !== d)
You can also check numeric values against another with a tolerance. Here are some examples:
assert(a === (2.0 +- 0.1)) assert(c !== (2.0 +- 0.1))
Class used via an implicit conversion to enable any two objects to be compared with
=== and !== with an Option[String] result and an enforced type constraint between
two object types.
Class used via an implicit conversion to enable any two objects to be compared with
=== and !== with an Option[String] result and an enforced type constraint between
two object types. For example:
assert(a === b) assert(c !== d)
You can also check numeric values against another with a tolerance. Here are some examples:
assert(a === (2.0 +- 0.1)) assert(c !== (2.0 +- 0.1))
The benefit of using assert(a === b) rather than assert(a == b) in ScalaTest code is
that a TestFailedException produced by the former will include the values of a and b
in its detail message.
Note: This class has "Legacy" in its name because its approach to error messages will eventually be replaced by macros. Once ScalaTest no longer supports Scala 2.9,
this class will be deprecated in favor of class Equalizer. Instead of obtaining nice error messages via the Option[String]
returned by the methods of this class, the error messages will be obtained by a macro. The "legacy" approach to good error messages will continue to be
used, however, until ScalaTest no longer supports Scala 2.9, since macros were introduced to Scala (in experimental form) in 2.10.
The primary constructor takes one object, left, whose type is being converted to Equalizer. The left
value may be a null reference, because this is allowed by Scala's == operator.
Class used via an implicit conversion to enable any two objects to be compared with
=== and !== with an Option[String] result and no enforced type constraint between
two object types.
Class used via an implicit conversion to enable any two objects to be compared with
=== and !== with an Option[String] result and no enforced type constraint between
two object types. For example:
assert(a === b) assert(c !== d)
You can also check numeric values against another with a tolerance. Here are some examples:
assert(a === (2.0 +- 0.1)) assert(c !== (2.0 +- 0.1))
The benefit of using assert(a === b) rather than assert(a == b) in ScalaTest code is
that a TestFailedException produced by the former will include the values of a and b
in its detail message.
Note: This class has "Legacy" in its name because its approach to error messages will eventually be replaced by macros. Once ScalaTest no longer supports Scala 2.9,
this class will be deprecated in favor of class Equalizer. Instead of obtaining nice error messages via the Option[String]
returned by the methods of this class, the error messages will be obtained by a macro. The "legacy" approach to good error messages will continue to be
used, however, until ScalaTest no longer supports Scala 2.9, since macros were introduced to Scala (in experimental form) in 2.10.
The primary constructor takes one object, left, whose type is being converted to Equalizer. The left
value may be a null reference, because this is allowed by Scala's == operator.
Provides a Constraint[A, B] class for any two types A and B, enforcing the type constraint that B is
implicitly convertible to A, given an implicit Equivalence[A].
Provides a Constraint[A, B] class for any two types A and B, enforcing the type constraint that B is
implicitly convertible to A, given an implicit Equivalence[A].
The returned Constraint's areEqual method uses the implicitly passed Equivalence[A]'s
areEquivalent method to determine equality.
This method is overridden and made implicit by subtraits
ConversionCheckedTripleEquals) and
ConversionCheckedLegacyTripleEquals, and
overriden as non-implicit by the other subtraits in this package.
an Equivalence[A] type class to which the Constraint.areEqual method will delegate to determine equality.
an implicit conversion from B to A
a Constraint[A, B] whose areEqual method delegates to the areEquivalent method of
the passed Equivalence[A].
Provides a Constraint[A, B] for any two types A and B, enforcing the type constraint
that A must be a subtype of B, given an explicit Equivalence[B].
Provides a Constraint[A, B] for any two types A and B, enforcing the type constraint
that A must be a subtype of B, given an explicit Equivalence[B].
This method is used to enable the Explicitly DSL for
TypeCheckedTripleEquals by requiring an explicit Equivalance[B], but
taking an implicit function that provides evidence that A is a subtype of B.
The returned Constraint's areEqual method uses the implicitly passed Equivalence[B]'s
areEquivalent method to determine equality.
This method is overridden and made implicit by subtraits
LowPriorityTypeCheckedConstraint (extended by
TypeCheckedTripleEquals), and
LowPriorityTypeCheckedLegacyConstraint (extended by
TypeCheckedLegacyTripleEquals), and
overriden as non-implicit by the other subtraits in this package.
an Equivalence[B] type class to which the Constraint.areEqual method
will delegate to determine equality.
evidence that A is a subype of B
a Constraint[A, B] whose areEqual method delegates to the
areEquivalent method of the passed Equivalence[B].
Provides a Constraint[A, B] class for any two types A and B, enforcing the type constraint that A is
implicitly convertible to B, given an explicit Equivalence[B].
Provides a Constraint[A, B] class for any two types A and B, enforcing the type constraint that A is
implicitly convertible to B, given an explicit Equivalence[B].
This method is used to enable the Explicitly DSL for
ConversionCheckedTripleEquals by requiring an explicit Equivalance[B], but
taking an implicit function that converts from A to B.
The returned Constraint's areEqual method uses the implicitly passed Equivalence[B]'s
areEquivalent method to determine equality.
This method is overridden and made implicit by subtraits
LowPriorityConversionCheckedConstraint (extended by
ConversionCheckedTripleEquals), and
LowPriorityConversionCheckedLegacyConstraint (extended by
ConversionCheckedLegacyTripleEquals), and
overriden as non-implicit by the other subtraits in this package.
a Constraint[A, B] whose areEqual method delegates to the areEquivalent method of
the passed Equivalence[B].
Provides a Constraint[A, B] for any two types A and B, enforcing the type constraint
that B must be a subtype of A, given an explicit Equivalence[A].
Provides a Constraint[A, B] for any two types A and B, enforcing the type constraint
that B must be a subtype of A, given an explicit Equivalence[A].
This method is used to enable the Explicitly DSL for
TypeCheckedTripleEquals by requiring an explicit Equivalance[B], but
taking an implicit function that provides evidence that A is a subtype of B. For example, under TypeCheckedTripleEquals,
this method (as an implicit method), would be used to compile this statement:
def closeEnoughTo1(num: Double): Boolean = (num === 1.0)(decided by forgivingEquality)
The returned Constraint's areEqual method uses the implicitly passed Equivalence[A]'s
areEquivalent method to determine equality.
This method is overridden and made implicit by subtraits
TypeCheckedTripleEquals) and
TypeCheckedLegacyTripleEquals, and
overriden as non-implicit by the other subtraits in this package.
evidence that B is a subype of A
a Constraint[A, B] whose areEqual method delegates to the areEquivalent method of
the passed Equivalence[A].
Provides a Constraint[A, B] class for any two types A and B, enforcing the type constraint that B is
implicitly convertible to A, given an explicit Equivalence[A].
Provides a Constraint[A, B] class for any two types A and B, enforcing the type constraint that B is
implicitly convertible to A, given an explicit Equivalence[A].
This method is used to enable the Explicitly DSL for
ConversionCheckedTripleEquals by requiring an explicit Equivalance[A], but
taking an implicit function that converts from B to A. For example, under ConversionCheckedTripleEquals,
this method (as an implicit method), would be used to compile this statement:
def closeEnoughTo1(num: Double): Boolean = (num === 1.0)(decided by forgivingEquality)
The returned Constraint's areEqual method uses the implicitly passed Equivalence[A]'s
areEquivalent method to determine equality.
This method is overridden and made implicit by subtraits
ConversionCheckedTripleEquals) and
ConversionCheckedLegacyTripleEquals, and
overriden as non-implicit by the other subtraits in this package.
an Equivalence[A] type class to which the Constraint.areEqual method will delegate to determine equality.
a Constraint[A, B] whose areEqual method delegates to the areEquivalent method of
the passed Equivalence[A].
Converts to an CheckingEqualizer that provides === and !== operators
that result in Boolean and enforce a type constraint.
Converts to an CheckingEqualizer that provides === and !== operators
that result in Boolean and enforce a type constraint.
This method is overridden and made implicit by subtraits TypeCheckedTripleEquals and
ConversionCheckedTripleEquals, and overriden as
non-implicit by the other subtraits in this package.
the object whose type to convert to CheckingEqualizer.
if left is null.
Converts to an Equalizer that provides === and !== operators that
result in Boolean and enforce no type constraint.
Converts to an Equalizer that provides === and !== operators that
result in Boolean and enforce no type constraint.
This method is overridden and made implicit by subtrait TripleEquals and overriden as non-implicit by the other
subtraits in this package.
the object whose type to convert to Equalizer.
if left is null.
Converts to a LegacyCheckingEqualizer that provides === and !== operators
that result in Option[String] and enforce a type constraint.
Converts to a LegacyCheckingEqualizer that provides === and !== operators
that result in Option[String] and enforce a type constraint.
This method is overridden and made implicit by subtraits TypeCheckedLegacyTripleEquals
and ConversionCheckedLegacyTripleEquals, and
overriden as non-implicit by the other subtraits in this package.
the object whose type to convert to LegacyCheckingEqualizer.
if left is null.
Converts to a LegacyEqualizer that provides === and !== operators that
result in Option[String] and enforce no type constraint.
Converts to a LegacyEqualizer that provides === and !== operators that
result in Option[String] and enforce no type constraint.
This method is overridden and made implicit by subtrait LegacyTripleEquals and overriden as non-implicit
by the other subtraits in this package.
the object whose type to convert to LegacyEqualizer.
if left is null.
Provides a Constraint[A, B] class for any two types A and B, enforcing the type constraint that A is
implicitly convertible to B, given an implicit Equivalence[B].
Provides a Constraint[A, B] class for any two types A and B, enforcing the type constraint that A is
implicitly convertible to B, given an implicit Equivalence[B].
The returned Constraint's areEqual method uses the implicitly passed Equivalence[B]'s
areEquivalent method to determine equality.
This method is overridden and made implicit by subtraits
LowPriorityConversionCheckedConstraint (extended by
ConversionCheckedTripleEquals), and
LowPriorityConversionCheckedLegacyConstraint (extended by
ConversionCheckedLegacyTripleEquals), and
overriden as non-implicit by the other subtraits in this package.
an implicit conversion from A to B
a Constraint[A, B] whose areEqual method delegates to the areEquivalent method of
the passed Equivalence[B].
Provides a Constraint[A, B] for any two types A and B, enforcing the type constraint
that A must be a subtype of B, given an implicit Equivalence[B].
Provides a Constraint[A, B] for any two types A and B, enforcing the type constraint
that A must be a subtype of B, given an implicit Equivalence[B].
The returned Constraint's areEqual method uses the implicitly passed Equivalence[A]'s
areEquivalent method to determine equality.
This method is overridden and made implicit by subtraits
LowPriorityTypeCheckedConstraint (extended by
TypeCheckedTripleEquals), and
LowPriorityTypeCheckedLegacyConstraint (extended by
TypeCheckedLegacyTripleEquals), and
overriden as non-implicit by the other subtraits in this package.
an Equivalence[B] type class to which the Constraint.areEqual method
will delegate to determine equality.
evidence that A is a subype of B
a Constraint[A, B] whose areEqual method delegates to the
areEquivalent method of the passed Equivalence[B].
Provides a Constraint[A, B] for any two types A and B, enforcing the type constraint
that B must be a subtype of A, given an implicit Equivalence[A].
Provides a Constraint[A, B] for any two types A and B, enforcing the type constraint
that B must be a subtype of A, given an implicit Equivalence[A].
The returned Constraint's areEqual method uses the implicitly passed Equivalence[A]'s
areEquivalent method to determine equality.
This method is overridden and made implicit by subtraits
TypeCheckedTripleEquals) and
TypeCheckedLegacyTripleEquals, and
overriden as non-implicit by the other subtraits in this package.
evidence that B is a subype of A
a Constraint[A, B] whose areEqual method delegates to the areEquivalent method of
the passed Equivalence[A].
Provides a Constraint[A, B] class for any two types A and B, with no type constraint enforced, given an
implicit Equality[A].
Provides a Constraint[A, B] class for any two types A and B, with no type constraint enforced, given an
implicit Equality[A].
The returned Constraint's areEqual method uses the implicitly passed Equality[A]'s
areEqual method to determine equality.
This method is overridden and made implicit by subtraits TripleEquals and
LegacyTripleEquals, and
overriden as non-implicit by the other subtraits in this package.
an Equality[A] type class to which the Constraint.areEqual method will delegate to determine equality.
a Constraint[A, B] whose areEqual method delegates to the areEqual method of
the passed Equality[A].
Returns a TripleEqualsInvocationOnSpread[T], given an Spread[T], to facilitate
the “<left> should !== (<pivot> +- <tolerance>)”
syntax of Matchers.
Returns a TripleEqualsInvocationOnSpread[T], given an Spread[T], to facilitate
the “<left> should !== (<pivot> +- <tolerance>)”
syntax of Matchers.
the Spread[T] against which to compare the left-hand value
a TripleEqualsInvocationOnSpread wrapping the passed Spread[T] value, with
expectingEqual set to false.
Returns a TripleEqualsInvocation[Null], given a null reference, to facilitate
the “<left> should !== null” syntax
of Matchers.
Returns a TripleEqualsInvocation[Null], given a null reference, to facilitate
the “<left> should !== null” syntax
of Matchers.
a null reference
a TripleEqualsInvocation wrapping the passed null value, with expectingEqual
set to false.
Returns a TripleEqualsInvocation[T], given an object of type T, to facilitate
the “<left> should !== <right>” syntax
of Matchers.
Returns a TripleEqualsInvocation[T], given an object of type T, to facilitate
the “<left> should !== <right>” syntax
of Matchers.
the right-hand side value for an equality assertion
a TripleEqualsInvocation wrapping the passed right value, with expectingEqual
set to false.
Returns a TripleEqualsInvocationOnSpread[T], given an Spread[T], to facilitate
the “<left> should === (<pivot> +- <tolerance>)”
syntax of Matchers.
Returns a TripleEqualsInvocationOnSpread[T], given an Spread[T], to facilitate
the “<left> should === (<pivot> +- <tolerance>)”
syntax of Matchers.
the Spread[T] against which to compare the left-hand value
a TripleEqualsInvocationOnSpread wrapping the passed Spread[T] value, with
expectingEqual set to true.
Returns a TripleEqualsInvocation[Null], given a null reference, to facilitate
the “<left> should === null” syntax
of Matchers.
Returns a TripleEqualsInvocation[Null], given a null reference, to facilitate
the “<left> should === null” syntax
of Matchers.
a null reference
a TripleEqualsInvocation wrapping the passed null value, with expectingEqual
set to true.
Returns a TripleEqualsInvocation[T], given an object of type T, to facilitate
the “<left> should === <right>” syntax
of Matchers.
Returns a TripleEqualsInvocation[T], given an object of type T, to facilitate
the “<left> should === <right>” syntax
of Matchers.
the right-hand side value for an equality assertion
a TripleEqualsInvocation wrapping the passed right value, with expectingEqual
set to true.
Returns an Equality[A] for any type A that determines equality
by first calling .deep on any Array (on either the left or right side),
then comparing the resulting objects with ==.
Returns an Equality[A] for any type A that determines equality
by first calling .deep on any Array (on either the left or right side),
then comparing the resulting objects with ==.
a default Equality for type A
Trait that defines abstract methods used to enforce compile-time type constraints for equality comparisons, and defines
===and!==operators used by matchers.The abstract methods of this trait are selectively implemented as implicit by subclasses to enable a spectrum of type constraints for the
===and!==operators. As an illustration, if in the expression,a === b, the type ofaisAandbisB, the following three levels of compile-time checking can be obtained fromTripleEqualsSupportsubtraits:Unchecked -
AandBcan be any two types. This (weakest) constraint level is available from subtraitsTripleEqualsandLegacyTripleEquals.Conversion checked -
Amust be a subtype ofB, or vice versa, or an implicit conversion must be available that convertsAtoB, or vice versa. (BothAandBcan be the same type, because a type is considered a subtype of itself.) This (intermediate) constraint level is available from subtraitsConversionCheckedTripleEqualsandConversionCheckedLegacyTripleEquals.Type checked -
Amust be a subtype ofB, or vice versa. (BothAandBcan be the same type, because a type is considered a subtype of itself.) This (strongest) constraint level is available from subtraitsTypeCheckedTripleEqualsandTypeCheckedLegacyTripleEquals.The difference between the regular and “legacy” variants of each pair of traits is that the
===and!==operators provided by the regular variants result inBoolean, whereas those of the legacy variants result inOption[String]. For example, were you to mix inTripleEquals, the expression1 + 1 === 3would returnfalse. Were you to mix inLegacyTripleEquals, by contrast, the expression1 + 1 === 3would returnSome("2 did not equal 3").The purpose of the legacy variants is to maintain compatibility with existing code that uses ScalaTest's original
===defined in traitorg.scalatest.Assertions. This===operator returned anOption[String]to facilitate better error messages. With the advent of macros in Scala 2.10, it is possible to obtain good error messages by makingasserta macro. Once ScalaTest no longer supports Scala 2.9, the legacy variants (LegacyTripleEquals,ConversionCheckedLegacyTripleEquals, andTypeCheckedLegacyTripleEquals) will be deprecated and eventually removed,===will return onlyBoolean, and good error messages will be obtained via macros.This trait defines all methods that need to be defined implicitly by the six subtraits so that if multiple subtraits are used together, the inner-most subtrait in scope can not only enable the implicits it needs by overriding or hiding those methods (currently-in-scope as regular, non-implicit methods) and making them implicit, it can also disable any implicits enabled by its sibling subtraits in enclosing scopes. For example, if your test class mixes in
TypeCheckedTripleEquals, inside your test class the following methods will be implicit:convertToCheckingEqualizertypeCheckedConstraintlowPriorityTypeCheckedConstraintconvertEquivalenceToAToBConstraintconvertEquivalenceToBToAConstraintIf in the body of a test you want to turn off the type checking, you can import the members of
TripleEqualsin the body of that test. This will not only hide non-implicit methodsconvertToEqualizerunconstrainedEqualityofTypeCheckedTripleEquals, replacing those with implicit ones defined inTripleEquals, it will also hide the three methods made implicit inTypeCheckedTripleEquals(and listed above), replacing them by non-implicit ones.In short, you should be able to select a primary constraint level via either a mixin or import, then change that in nested scopes however you want, again either through a mixin or import, without getting any implicit conversion ambiguity. The innermost constraint level in scope will always be in force.