org.scalatest.fixture.FixtureSpec
The ===
operation compares this Equalizer
's left
value (passed
to the constructor, usually via an implicit conversion) with the passed right
value
for equality as determined by the expression left == right
The ===
operation compares this Equalizer
's left
value (passed
to the constructor, usually via an implicit conversion) with the passed right
value
for equality as determined by the expression left == right
.
If true
, ===
returns None
. Else, ===
returns
a Some
whose String
value indicates the left
and right
values.
In its typical usage, the Option[String]
returned by ===
will be passed to one of two
of trait Assertion
' overloaded assert
methods. If None
,
which indicates the assertion succeeded, assert
will return normally. But if Some
is passed,
which indicates the assertion failed, assert
will throw a TestFailedException
whose detail
message will include the String
contained inside the Some
, which in turn includes the
left
and right
values. This TestFailedException
is typically embedded in a
Report
and passed to a Reporter
, which can present the left
and right
values to the user.
This method is used to compare the receiver object (this
)
with the argument object (arg0
) for equivalence
This method is used to compare the receiver object (this
)
with the argument object (arg0
) for equivalence.
The default implementations of this method is an equivalence relation:
x
of type Any
,
x.equals(x)
should return true
.x
and y
of type
Any
, x.equals(y)
should return true
if and only
if y.equals(x)
returns true
.x
, y
, and z
of type AnyRef
if x.equals(y)
returns true
and
y.equals(z)
returns
true
, then x.equals(z)
should return true
.
If you override this method, you should verify that
your implementation remains an equivalence relation.
Additionally, when overriding this method it is often necessary to
override hashCode
to ensure that objects that are
"equal" (o1.equals(o2)
returns true
)
hash to the same Int
(o1.hashCode.equals(o2.hashCode)
).
the object to compare against this object for equality.
true
if the receiver object is equivalent to the argument; false
otherwise.
Returns a hash code value for the object
Returns a hash code value for the object.
The default hashing algorithm is platform dependent.
Note that it is allowed for two objects to have identical hash
codes (o1.hashCode.equals(o2.hashCode)
) yet not be
equal (o1.equals(o2)
returns false
). A
degenerate implementation could always return 0
.
However, it is required that if two objects are equal
(o1.equals(o2)
returns true
) that they
have identical hash codes
(o1.hashCode.equals(o2.hashCode)
). Therefore, when
overriding this method, be sure to verify that the behavior is
consistent with the equals
method.
Returns a string representation of the object
Returns a string representation of the object.
The default representation is platform dependent.
Class used via an implicit conversion to enable any two objects to be compared with
===
in assertions in tests. For example:The benefit of using
assert(a === b)
rather thanassert(a == b)
is that aTestFailedException
produced by the former will include the values ofa
andb
in its detail message. The implicit method that performs the conversion fromAny
toEqualizer
isconvertToEqualizer
in traitAssertions
.In case you're not familiar with how implicit conversions work in Scala, here's a quick explanation. The
convertToEqualizer
method inAssertions
is defined as an "implicit" method that takes anAny
, which means you can pass in any object, and it will convert it to anEqualizer
. TheEqualizer
has===
defined. Most objects don't have===
defined as a method on them. Take two Strings, for example:Given this code, the Scala compiler looks for an
===
method on classString
, because that's the class of"hello"
.String
doesn't define===
, so the compiler looks for an implicit conversion fromString
to something that does have an===
method, and it finds theconvertToEqualizer
method. It then rewrites the code to this:So inside a
Suite
(which mixes inAssertions
,===
will work on anything. The only situation in which the implicit conversion wouldn't happen is on types that have an===
method already defined.The primary constructor takes one object,
left
, whose type is being converted toEqualizer
. Theleft
value may be anull
reference, because this is allowed by Scala's==
operator.