Returns a TripleEqualsInvocationOnInterval[T], given an Interval[T], to facilitate
the “<left> should !== (<pivot> +- <tolerance>)”
syntax of Matchers.
Returns a TripleEqualsInvocationOnInterval[T], given an Interval[T], to facilitate
the “<left> should !== (<pivot> +- <tolerance>)”
syntax of Matchers.
the Interval[T] against which to compare the left-hand value
a TripleEqualsInvocationOnInterval wrapping the passed Interval[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 TripleEqualsInvocationOnInterval[T], given an Interval[T], to facilitate
the “<left> should === (<pivot> +- <tolerance>)”
syntax of Matchers.
Returns a TripleEqualsInvocationOnInterval[T], given an Interval[T], to facilitate
the “<left> should === (<pivot> +- <tolerance>)”
syntax of Matchers.
the Interval[T] against which to compare the left-hand value
a TripleEqualsInvocationOnInterval wrapping the passed Interval[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.
Provides an EqualityConstraint[A, B] class for any two types A and B, enforcing the type constraint that B is implicitly convertible to A, given an implicit Equality[A].
Provides an EqualityConstraint[A, B] class for any two types A and B, enforcing the type constraint that B is implicitly convertible to A, given an implicit Equality[A].
The implicitly passed Equality[A] must be used to determine equality by the returned EqualityConstraint's
areEqual method.
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 Equality[A] type class to which the EqualityConstraint.areEqual method will delegate to determine equality.
an implicit conversion from B to A
an EqualityConstraint[A, B] whose areEqual method delegates to the areEqual method of
the passed Equality[A].
Convert to an CheckingEqualizer that provides === and !== operators that result in Boolean and enforce a type constraint.
Convert 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.
Convert to an Equalizer that provides === and !== operators that
result in Boolean and enforce no type constraint.
Convert 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.
Convert to a LegacyCheckingEqualizer that provides === and !== operators that result in Option[String] and
enforce a type constraint.
Convert 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.
Convert to a LegacyEqualizer that provides === and !== operators that
result in Option[String] and enforce no type constraint.
Convert 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.
Return an Equality[A] for any type A that determines equality via the == operator on type A.
Return an Equality[A] for any type A that determines equality via the == operator on type A.
a DefaultEquality for type A
Provides an EqualityConstraint[A, B] class for any two types A and B, enforcing the type constraint that A is implicitly convertible to B, given an implicit Equality[A].
Provides an EqualityConstraint[A, B] class for any two types A and B, enforcing the type constraint that A is implicitly convertible to B, given an implicit Equality[A].
The implicitly passed Equality[A] must be used to determine equality by the returned EqualityConstraint's
areEqual method.
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
an EqualityConstraint[A, B] whose areEqual method delegates to the areEqual method of
the passed Equality[A].
Provides an EqualityConstraint[A, B] class for any two types A and B, enforcing the type constraint that A must be a subtype of B, given an implicit Equality[A].
Provides an EqualityConstraint[A, B] class for any two types A and B, enforcing the type constraint that A must be a subtype of B, given an implicit Equality[A].
The implicitly passed Equality[A] must be used to determine equality by the returned EqualityConstraint's
areEqual method.
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 Equality[A] type class to which the EqualityConstraint.areEqual method
will delegate to determine equality.
evidence that A is a subype of B
an EqualityConstraint[A, B] whose areEqual method delegates to the
areEqual method of the passed Equality[A].
Provides an EqualityConstraint[A, B] class for any two types A and B, enforcing the type constraint that B must be a subtype of A, given an implicit Equality[A].
Provides an EqualityConstraint[A, B] class for any two types A and B, enforcing the type constraint that B must be a subtype of A, given an implicit Equality[A].
The implicitly passed Equality[A] must be used to determine equality by the returned EqualityConstraint's
areEqual method.
This method is overridden and made implicit by subtraits
TypeCheckedTripleEquals) and
TypeCheckedLegacyTripleEquals, and
overriden as non-implicit by the other subtraits in this package.
an Equality[A] type class to which the EqualityConstraint.areEqual method will delegate to determine equality.
evidence that B is a subype of A
an EqualityConstraint[A, B] whose areEqual method delegates to the areEqual method of
the passed Equality[A].
Provides an EqualityConstraint[A, B] class for any two types A and B, with no type constraint enforced, given an
implicit Equality[A].
Provides an EqualityConstraint[A, B] class for any two types A and B, with no type constraint enforced, given an
implicit Equality[A].
The implicitly passed Equality[A] must be used to determine equality by the returned EqualityConstraint's
areEqual method.
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 EqualityConstraint.areEqual method will delegate to determine equality.
an EqualityConstraint[A, B] whose areEqual method delegates to the areEqual method of
the passed Equality[A].
Provides
===and!==operators that returnBoolean, delegate the equality determination to anEqualitytype class, and require the types of the two values compared to be in a subtype/supertype relationship.TypeCheckedTripleEqualsis useful (in both production and test code) when you need determine equality for a type of object differently than itsequalsmethod—either you can't change theequalsmethod, or theequalsmethod is sensible generally, but you're in a special situation where you need something else—and/or you want to enforce at compile-time that the types of the compared values are in a subtype/supertype relationship.This trait is the strictest of the three triple equals traits, enforcing a stronger constraint than both
TripleEquals(the most lenient) andConversionCheckedTripleEquals(the middle ground). IfTripleEqualsis mixed in or imported, the===can be used with any two types and still compile. IfTypeCheckedTripleEqualsis mixed in or imported, however, only types in a subtype or supertype relationship with each other (including when both types are exactly the same) will compile.ConversionCheckedTripleEqualsis slightly more accomodating, because in addition to compiling any use of===that will compile under TypeCheckedTripleEquals, it will also compile type types that would be rejected byTypeCheckedTripleEquals, so long as an implicit conversion (in either direction) from one type to another is available.For example, under
TypeCheckedTripleEquals, the following use of===will not compile, becauseIntandLongare not in a subtype/supertype relationship. (I.e.,Intis not a subtype or supertype ofLong):Trait
TypeCheckedTripleEqualsrejects typesIntandLongbecause they are not directly related via subtyping. However, an implicit widening conversion fromIntto Long does exist (imported implicitly fromscala.Predef), soConversionCheckedTripleEqualswill allow it:The implicit conversion can go in either direction: from the left type to the right type, or vice versa. In the above expression the implicit conversion goes from left to right (the
Inton the left to theLongon the right). It also works the other way:This trait will override or hide implicit methods defined by its sibling traits,
TripleEqualsorTypeCheckedTripleEquals, and can therefore be used to temporarily turn on or off conversion checking in a limited scope. Here's an example, in whichTypeCheckedTripleEqualswill cause a compiler error:Because
IntandLongare not in a subtype/supertype relationship, comparing1and1Lin the context ofTypeCheckedTripleEqualswill generate a compiler error:Example.scala:9: error: types Int and Long do not adhere to the equality constraint selected for the === and !== operators; they must either be in a subtype/supertype relationship, or, if ConversionCheckedTripleEquals is in force, implicitly convertible in one direction or the other; the missing implicit parameter is of type org.scalautils.EqualityConstraint[Int,Long] if (a === b) 0 // This line won't compile ^ one error foundYou can “relax” the type checking (i.e., by additionally allowing implicitly convertible types) locally by importing the members of
ConversionCheckedTripleEqualsin a limited scope:package org.scalautils.examples.conversioncheckedtripleequals import org.scalautils._ import TypeCheckedTripleEquals._ object Example { def cmp(a: Int, b: Long): Int = { import ConversionCheckedTripleEquals._ if (a === b) 0 else if (a < b) -1 else 1 } def cmp(s: String, t: String): Int = { if (s === t) 0 else if (s < t) -1 else 1 } }With the above change, the
Example.scalafile compiles fine. Conversion checking is enabled only inside the firstcmpmethod that takes anIntand aLong.TypeCheckedTripleEqualsis still enforcing its type constraint, for example, for thes === texpression in the other overloadedcmpmethod that takes strings.Because the methods in
ConversionCheckedTripleEquals(and its siblings) override all the methods defined in supertypeEqualityConstraints, you can achieve the same kind of nested tuning of equality constraints whether you mix in traits, import from companion objects, or use some combination of both.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.
An alternative way to solve an unwanted compiler error caused by an over-zealous equality type constraint is to convert one side or the other to type
Any. BecauseAnyis a supertype of everything, any level of equality type constraint will be satisfied. TheAsAnytrait offers a convenient syntax, theasAnymethod, for this purpose: