trait Assertions extends TripleEquals
Trait that contains ScalaTest's basic assertion methods.
You can use the assertions provided by this trait in any ScalaTest Suite
,
because Suite
mixes in this trait. This trait is designed to be used independently of anything else in ScalaTest, though, so you
can mix it into anything. (You can alternatively import the methods defined in this trait. For details, see the documentation
for the Assertions
companion object.
In any Scala program, you can write assertions by invoking assert
and passing in a Boolean
expression,
such as:
val left = 2 val right = 1 assert(left == right)
If the passed expression is true
, assert
will return normally. If false
,
Scala's assert
will complete abruptly with an AssertionError
. This behavior is provided by
the assert
method defined in object Predef
, whose members are implicitly imported into every
Scala source file. This Assertions
trait defines another assert
method that hides the
one in Predef
. It behaves the same, except that if false
is passed it throws
TestFailedException
instead of AssertionError
.
Why? Because unlike AssertionError
, TestFailedException
carries information about exactly
which item in the stack trace represents
the line of test code that failed, which can help users more quickly find an offending line of code in a failing test.
In addition, ScalaTest's assert
provides better error messages than Scala's assert
.
If you pass the previous Boolean
expression, left == right
to assert
in a ScalaTest test,
a failure will be reported that, because assert
is implemented as a macro,
includes reporting the left and right values.
For example, given the same code as above but using ScalaTest assertions:
import org.scalatest.Assertions._ val left = 2 val right = 1 assert(left == right)
The detail message in the thrown TestFailedException
from this assert
will be: "2 did not equal 1".
ScalaTest's assert
macro works by recognizing patterns in the AST of the expression passed to assert
and,
for a finite set of common expressions, giving an error message that an equivalent ScalaTest matcher
expression would give. Here are some examples, where a
is 1, b
is 2, c
is 3, d
is 4, xs
is List(a, b, c)
, and num
is 1.0:
assert(a == b || c >= d) // Error message: 1 did not equal 2, and 3 was not greater than or equal to 4 assert(xs.exists(_ == 4)) // Error message: List(1, 2, 3) did not contain 4 assert("hello".startsWith("h") && "goodbye".endsWith("y")) // Error message: "hello" started with "h", but "goodbye" did not end with "y" assert(num.isInstanceOf[Int]) // Error message: 1.0 was not instance of scala.Int assert(Some(2).isEmpty) // Error message: Some(2) was not empty
For expressions that are not recognized, the macro currently prints out a string
representation of the (desugared) AST and adds "was false"
. Here are some examples of
error messages for unrecognized expressions:
assert(None.isDefined) // Error message: scala.None.isDefined was false assert(xs.exists(i => i > 10)) // Error message: xs.exists(((i: Int) => i.>(10))) was false
You can augment the standard error message by providing a String
as a second argument
to assert
, like this:
val attempted = 2 assert(attempted == 1, "Execution was attempted " + left + " times instead of 1 time")
Using this form of assert
, the failure report will be more specific to your problem domain, thereby
helping you debug the problem. This Assertions
trait also mixes in the
TripleEquals
, which gives you a ===
operator
that allows you to customize Equality
, perform equality checks with numeric
Tolerance
, and enforce type constraints at compile time with
sibling traits TypeCheckedTripleEquals
and
ConversionCheckedTripleEquals
.
Expected results
Although the assert
macro provides a natural, readable extension to Scala's assert
mechanism that
provides good error messages, as the operands become lengthy, the code becomes less readable. In addition, the error messages
generated for ==
and ===
comparisons
don't distinguish between actual and expected values. The operands are just called left
and right
,
because if one were named expected
and the other actual
, it would be difficult for people to
remember which was which. To help with these limitations of assertions, Suite
includes a method called assertResult
that
can be used as an alternative to assert
. To use assertResult
, you place
the expected value in parentheses after assertResult
, followed by curly braces containing code
that should result in the expected value. For example:
val a = 5 val b = 2 assertResult(2) { a - b }
In this case, the expected value is 2
, and the code being tested is a - b
. This assertion will fail, and
the detail message in the TestFailedException
will read, "Expected 2, but got 3."
Forcing failures
If you just need the test to fail, you can write:
fail()
Or, if you want the test to fail with a message, write:
fail("I've got a bad feeling about this")
Achieving success
In async style tests, you must end your test body with either Future[Assertion]
or
Assertion
. ScalaTest's assertions (including matcher expressions) have result type
Assertion
, so ending with an assertion will satisfy the compiler.
If a test body or function body passed to Future.map
does
not end with type Assertion
, however, you can fix the type error by placing
succeed
at the end of the
test or function body:
succeed // Has type Assertion
Expected exceptions
Sometimes you need to test whether a method throws an expected exception under certain circumstances, such as when invalid arguments are passed to the method. You can do this in the JUnit 3 style, like this:
val s = "hi" try { s.charAt(-1) fail() } catch { case _: IndexOutOfBoundsException => // Expected, so continue }
If charAt
throws IndexOutOfBoundsException
as expected, control will transfer
to the catch case, which does nothing. If, however, charAt
fails to throw an exception,
the next statement, fail()
, will be run. The fail
method always completes abruptly with
a TestFailedException
, thereby signaling a failed test.
To make this common use case easier to express and read, ScalaTest provides two methods:
assertThrows
and intercept
.
Here's how you use assertThrows
:
val s = "hi" assertThrows[IndexOutOfBoundsException] { // Result type: Assertion s.charAt(-1) }
This code behaves much like the previous example. If charAt
throws an instance of IndexOutOfBoundsException
,
assertThrows
will return Succeeded
. But if charAt
completes normally, or throws a different
exception, assertThrows
will complete abruptly with a TestFailedException
.
The intercept
method behaves the same as assertThrows
, except that instead of returning Succeeded
,
intercept
returns the caught exception so that you can inspect it further if you wish. For example, you may need
to ensure that data contained inside the exception have expected values. Here's an example:
val s = "hi" val caught = intercept[IndexOutOfBoundsException] { // Result type: IndexOutOfBoundsException s.charAt(-1) } assert(caught.getMessage.indexOf("-1") != -1)
Checking that a snippet of code does or does not compile
Often when creating libraries you may wish to ensure that certain arrangements of code that
represent potential “user errors” do not compile, so that your library is more error resistant.
ScalaTest's Assertions
trait includes the following syntax for that purpose:
assertDoesNotCompile("val a: String = 1")
If you want to ensure that a snippet of code does not compile because of a type error (as opposed to a syntax error), use:
assertTypeError("val a: String = 1")
Note that the assertTypeError
call will only succeed if the given snippet of code does not
compile because of a type error. A syntax error will still result on a thrown TestFailedException
.
If you want to state that a snippet of code does compile, you can make that more obvious with:
assertCompiles("val a: Int = 1")
Although the previous three constructs are implemented with macros that determine at compile time whether the snippet of code represented by the string does or does not compile, errors are reported as test failures at runtime.
Assumptions
Trait Assertions
also provides methods that allow you to cancel a test.
You would cancel a test if a resource required by the test was unavailable. For example, if a test
requires an external database to be online, and it isn't, the test could be canceled to indicate
it was unable to run because of the missing database. Such a test assumes a database is
available, and you can use the assume
method to indicate this at the beginning of
the test, like this:
assume(database.isAvailable)
For each overloaded assert
method, trait Assertions
provides an
overloaded assume
method with an identical signature and behavior, except the
assume
methods throw TestCanceledException
whereas the
assert
methods throw TestFailedException
. As with assert
,
assume
hides a Scala method in Predef
that performs a similar
function, but throws AssertionError
. And just as you can with assert
,
you will get an error message extracted by a macro from the AST passed to assume
, and can
optionally provide a clue string to augment this error message. Here are some examples:
assume(database.isAvailable, "The database was down again") assume(database.getAllUsers.count === 9)
Forcing cancelations
For each overloaded fail
method, there's a corresponding cancel
method
with an identical signature and behavior, except the cancel
methods throw
TestCanceledException
whereas the fail
methods throw
TestFailedException
. Thus if you just need to cancel a test, you can write:
cancel()
If you want to cancel the test with a message, just place the message in the parentheses:
cancel("Can't run the test because no internet connection was found")
Getting a clue
If you want more information that is provided by default by the methods if this trait,
you can supply a "clue" string in one of several ways.
The extra information (or "clues") you provide will
be included in the detail message of the thrown exception. Both
assert
and assertResult
provide a way for a clue to be
included directly, intercept
does not.
Here's an example of clues provided directly in assert
:
assert(1 + 1 === 3, "this is a clue")
and in assertResult
:
assertResult(3, "this is a clue") { 1 + 1 }
The exceptions thrown by the previous two statements will include the clue
string, "this is a clue"
, in the exception's detail message.
To get the same clue in the detail message of an exception thrown
by a failed intercept
call requires using withClue
:
withClue("this is a clue") { intercept[IndexOutOfBoundsException] { "hi".charAt(-1) } }
The withClue
method will only prepend the clue string to the detail
message of exception types that mix in the ModifiableMessage
trait.
See the documentation for ModifiableMessage
for more information.
If you wish to place a clue string after a block of code, see the documentation for
AppendedClues
.
Note: ScalaTest's assertTypeError
construct is in part inspired by the illTyped
macro
of shapeless.
- Source
- Assertions.scala
- Alphabetic
- By Inheritance
- Assertions
- TripleEquals
- TripleEqualsSupport
- AnyRef
- Any
- Hide All
- Show All
- Public
- All
Type Members
-
class
AssertionsHelper
extends AnyRef
Helper class used by code generated by the
assert
macro.Helper class used by code generated by the
assert
macro. -
class
CheckingEqualizer[L] extends AnyRef
- Definition Classes
- TripleEqualsSupport
-
class
Equalizer[L] extends AnyRef
- Definition Classes
- TripleEqualsSupport
Value Members
-
final
def
!=(arg0: Any): Boolean
- Definition Classes
- AnyRef → Any
-
def
!==[T](right: Spread[T]): TripleEqualsInvocationOnSpread[T]
- Definition Classes
- TripleEqualsSupport
-
def
!==(right: Null): TripleEqualsInvocation[Null]
- Definition Classes
- TripleEqualsSupport
-
def
!==[T](right: T): TripleEqualsInvocation[T]
- Definition Classes
- TripleEqualsSupport
-
final
def
##(): Int
- Definition Classes
- AnyRef → Any
-
final
def
==(arg0: Any): Boolean
- Definition Classes
- AnyRef → Any
-
def
===[T](right: Spread[T]): TripleEqualsInvocationOnSpread[T]
- Definition Classes
- TripleEqualsSupport
-
def
===(right: Null): TripleEqualsInvocation[Null]
- Definition Classes
- TripleEqualsSupport
-
def
===[T](right: T): TripleEqualsInvocation[T]
- Definition Classes
- TripleEqualsSupport
-
final
def
asInstanceOf[T0]: T0
- Definition Classes
- Any
-
macro
def
assert(condition: Boolean, clue: Any)(implicit prettifier: Prettifier, pos: Position): Assertion
Assert that a boolean condition, described in
String
message
, is true.Assert that a boolean condition, described in
String
message
, is true. If the condition istrue
, this method returns normally. Else, it throwsTestFailedException
with a helpful error message appended with theString
obtained by invokingtoString
on the specifiedclue
as the exception's detail message.This method is implemented in terms of a Scala macro that will generate a more helpful error message for expressions of this form:
- assert(a == b, "a good clue")
- assert(a != b, "a good clue")
- assert(a === b, "a good clue")
- assert(a !== b, "a good clue")
- assert(a > b, "a good clue")
- assert(a >= b, "a good clue")
- assert(a < b, "a good clue")
- assert(a <= b, "a good clue")
- assert(a startsWith "prefix", "a good clue")
- assert(a endsWith "postfix", "a good clue")
- assert(a contains "something", "a good clue")
- assert(a eq b, "a good clue")
- assert(a ne b, "a good clue")
- assert(a > 0 && b > 5, "a good clue")
- assert(a > 0 || b > 5, "a good clue")
- assert(a.isEmpty, "a good clue")
- assert(!a.isEmpty, "a good clue")
- assert(a.isInstanceOf[String], "a good clue")
- assert(a.length == 8, "a good clue")
- assert(a.size == 8, "a good clue")
- assert(a.exists(_ == 8), "a good clue")
At this time, any other form of expression will just get a
TestFailedException
with message saying the given expression was false. In the future, we will enhance this macro to give helpful error messages in more situations. In ScalaTest 2.0, however, this behavior was sufficient to allow the===
that returnsBoolean
to be the default in tests. This makes===
consistent between tests and production code.- condition
the boolean condition to assert
- clue
An objects whose
toString
method returns a message to include in a failure report.
- Exceptions thrown
NullArgumentException
ifmessage
isnull
.TestFailedException
if the condition isfalse
.
-
macro
def
assert(condition: Boolean)(implicit prettifier: Prettifier, pos: Position): Assertion
Assert that a boolean condition is true.
Assert that a boolean condition is true. If the condition is
true
, this method returns normally. Else, it throwsTestFailedException
.This method is implemented in terms of a Scala macro that will generate a more helpful error message for expressions of this form:
- assert(a == b)
- assert(a != b)
- assert(a === b)
- assert(a !== b)
- assert(a > b)
- assert(a >= b)
- assert(a < b)
- assert(a <= b)
- assert(a startsWith "prefix")
- assert(a endsWith "postfix")
- assert(a contains "something")
- assert(a eq b)
- assert(a ne b)
- assert(a > 0 && b > 5)
- assert(a > 0 || b > 5)
- assert(a.isEmpty)
- assert(!a.isEmpty)
- assert(a.isInstanceOf[String])
- assert(a.length == 8)
- assert(a.size == 8)
- assert(a.exists(_ == 8))
At this time, any other form of expression will get a
TestFailedException
with message saying the given expression was false. In the future, we will enhance this macro to give helpful error messages in more situations. In ScalaTest 2.0, however, this behavior was sufficient to allow the===
that returnsBoolean
to be the default in tests. This makes===
consistent between tests and production code.- condition
the boolean condition to assert
- Exceptions thrown
TestFailedException
if the condition isfalse
.
-
macro
def
assertCompiles(code: String)(implicit pos: Position): Assertion
Asserts that a given string snippet of code passes both the Scala parser and type checker.
Asserts that a given string snippet of code passes both the Scala parser and type checker.
You can use this to make sure a snippet of code compiles:
assertCompiles("val a: Int = 1")
Although
assertCompiles
is implemented with a macro that determines at compile time whether the snippet of code represented by the passed string compiles, errors (i.e., snippets of code that do not compile) are reported as test failures at runtime.- code
the snippet of code that should compile
-
macro
def
assertDoesNotCompile(code: String)(implicit pos: Position): Assertion
Asserts that a given string snippet of code does not pass either the Scala parser or type checker.
Asserts that a given string snippet of code does not pass either the Scala parser or type checker.
Often when creating libraries you may wish to ensure that certain arrangements of code that represent potential “user errors” do not compile, so that your library is more error resistant. ScalaTest's
Assertions
trait includes the following syntax for that purpose:assertDoesNotCompile("val a: String = \"a string")
Although
assertDoesNotCompile
is implemented with a macro that determines at compile time whether the snippet of code represented by the passed string doesn't compile, errors (i.e., snippets of code that do compile) are reported as test failures at runtime.Note that the difference between
assertTypeError
andassertDoesNotCompile
is thatassertDoesNotCompile
will succeed if the given code does not compile for any reason, whereasassertTypeError
will only succeed if the given code does not compile because of a type error. If the given code does not compile because of a syntax error, for example,assertDoesNotCompile
will return normally butassertTypeError
will throw aTestFailedException
.- code
the snippet of code that should not type check
-
def
assertResult(expected: Any)(actual: Any)(implicit prettifier: Prettifier, pos: Position): Assertion
Assert that the value passed as
expected
equals the value passed asactual
.Assert that the value passed as
expected
equals the value passed asactual
. If theactual
value equals theexpected
value (as determined by==
),assertResult
returns normally. Else,assertResult
throws aTestFailedException
whose detail message includes the expected and actual values.- expected
the expected value
- actual
the actual value, which should equal the passed
expected
value
- Exceptions thrown
TestFailedException
if the passedactual
value does not equal the passedexpected
value.
-
def
assertResult(expected: Any, clue: Any)(actual: Any)(implicit prettifier: Prettifier, pos: Position): Assertion
Assert that the value passed as
expected
equals the value passed asactual
.Assert that the value passed as
expected
equals the value passed asactual
. If theactual
equals theexpected
(as determined by==
),assertResult
returns normally. Else, ifactual
is not equal toexpected
,assertResult
throws aTestFailedException
whose detail message includes the expected and actual values, as well as theString
obtained by invokingtoString
on the passedclue
.- expected
the expected value
- clue
An object whose
toString
method returns a message to include in a failure report.- actual
the actual value, which should equal the passed
expected
value
- Exceptions thrown
TestFailedException
if the passedactual
value does not equal the passedexpected
value.
-
def
assertThrows[T <: AnyRef](f: ⇒ Any)(implicit classTag: ClassTag[T], pos: Position): Assertion
Ensure that an expected exception is thrown by the passed function value.
Ensure that an expected exception is thrown by the passed function value. The thrown exception must be an instance of the type specified by the type parameter of this method. This method invokes the passed function. If the function throws an exception that's an instance of the specified type, this method returns
Succeeded
. Else, whether the passed function returns normally or completes abruptly with a different exception, this method throwsTestFailedException
.Note that the type specified as this method's type parameter may represent any subtype of
AnyRef
, not justThrowable
or one of its subclasses. In Scala, exceptions can be caught based on traits they implement, so it may at times make sense to specify a trait that the intercepted exception's class must mix in. If a class instance is passed for a type that could not possibly be used to catch an exception (such asString
, for example), this method will complete abruptly with aTestFailedException
.Also note that the difference between this method and
intercept
is that this method does not return the expected exception, so it does not let you perform further assertions on that exception. Instead, this method returnsSucceeded
, which means it can serve as the last statement in an async- or safe-style suite. It also indicates to the reader of the code that nothing further is expected about the thrown exception other than its type. The recommended usage is to useassertThrows
by default,intercept
only when you need to inspect the caught exception further.- f
the function value that should throw the expected exception
- classTag
an implicit
ClassTag
representing the type of the specified type parameter.- returns
the
Succeeded
singleton, if an exception of the expected type is thrown
- Exceptions thrown
TestFailedException
if the passed function does not complete abruptly with an exception that's an instance of the specified type.
-
macro
def
assertTypeError(code: String)(implicit pos: Position): Assertion
Asserts that a given string snippet of code does not pass the Scala type checker, failing if the given snippet does not pass the Scala parser.
Asserts that a given string snippet of code does not pass the Scala type checker, failing if the given snippet does not pass the Scala parser.
Often when creating libraries you may wish to ensure that certain arrangements of code that represent potential “user errors” do not compile, so that your library is more error resistant. ScalaTest's
Assertions
trait includes the following syntax for that purpose:assertTypeError("val a: String = 1")
Although
assertTypeError
is implemented with a macro that determines at compile time whether the snippet of code represented by the passed string type checks, errors (i.e., snippets of code that do type check) are reported as test failures at runtime.Note that the difference between
assertTypeError
andassertDoesNotCompile
is thatassertDoesNotCompile
will succeed if the given code does not compile for any reason, whereasassertTypeError
will only succeed if the given code does not compile because of a type error. If the given code does not compile because of a syntax error, for example,assertDoesNotCompile
will return normally butassertTypeError
will throw aTestFailedException
.- code
the snippet of code that should not type check
-
val
assertionsHelper: AssertionsHelper
Helper instance used by code generated by macro assertion.
-
macro
def
assume(condition: Boolean, clue: Any)(implicit prettifier: Prettifier, pos: Position): Assertion
Assume that a boolean condition, described in
String
message
, is true.Assume that a boolean condition, described in
String
message
, is true. If the condition istrue
, this method returns normally. Else, it throwsTestCanceledException
with a helpful error message appended withString
obtained by invokingtoString
on the specifiedclue
as the exception's detail message.This method is implemented in terms of a Scala macro that will generate a more helpful error message for expressions of this form:
- assume(a == b, "a good clue")
- assume(a != b, "a good clue")
- assume(a === b, "a good clue")
- assume(a !== b, "a good clue")
- assume(a > b, "a good clue")
- assume(a >= b, "a good clue")
- assume(a < b, "a good clue")
- assume(a <= b, "a good clue")
- assume(a startsWith "prefix", "a good clue")
- assume(a endsWith "postfix", "a good clue")
- assume(a contains "something", "a good clue")
- assume(a eq b, "a good clue")
- assume(a ne b, "a good clue")
- assume(a > 0 && b > 5, "a good clue")
- assume(a > 0 || b > 5, "a good clue")
- assume(a.isEmpty, "a good clue")
- assume(!a.isEmpty, "a good clue")
- assume(a.isInstanceOf[String], "a good clue")
- assume(a.length == 8, "a good clue")
- assume(a.size == 8, "a good clue")
- assume(a.exists(_ == 8), "a good clue")
At this time, any other form of expression will just get a
TestCanceledException
with message saying the given expression was false. In the future, we will enhance this macro to give helpful error messages in more situations. In ScalaTest 2.0, however, this behavior was sufficient to allow the===
that returnsBoolean
to be the default in tests. This makes===
consistent between tests and production code.- condition
the boolean condition to assume
- clue
An objects whose
toString
method returns a message to include in a failure report.
- Exceptions thrown
NullArgumentException
ifmessage
isnull
.TestCanceledException
if the condition isfalse
.
-
macro
def
assume(condition: Boolean)(implicit prettifier: Prettifier, pos: Position): Assertion
Assume that a boolean condition is true.
Assume that a boolean condition is true. If the condition is
true
, this method returns normally. Else, it throwsTestCanceledException
.This method is implemented in terms of a Scala macro that will generate a more helpful error message for expressions of this form:
- assume(a == b)
- assume(a != b)
- assume(a === b)
- assume(a !== b)
- assume(a > b)
- assume(a >= b)
- assume(a < b)
- assume(a <= b)
- assume(a startsWith "prefix")
- assume(a endsWith "postfix")
- assume(a contains "something")
- assume(a eq b)
- assume(a ne b)
- assume(a > 0 && b > 5)
- assume(a > 0 || b > 5)
- assume(a.isEmpty)
- assume(!a.isEmpty)
- assume(a.isInstanceOf[String])
- assume(a.length == 8)
- assume(a.size == 8)
- assume(a.exists(_ == 8))
At this time, any other form of expression will just get a
TestCanceledException
with message saying the given expression was false. In the future, we will enhance this macro to give helpful error messages in more situations. In ScalaTest 2.0, however, this behavior was sufficient to allow the===
that returnsBoolean
to be the default in tests. This makes===
consistent between tests and production code.- condition
the boolean condition to assume
- Exceptions thrown
TestCanceledException
if the condition isfalse
.
-
def
cancel(cause: Throwable)(implicit pos: Position): Nothing
Throws
TestCanceledException
, with the passedThrowable
cause, to indicate a test failed.Throws
TestCanceledException
, with the passedThrowable
cause, to indicate a test failed. ThegetMessage
method of the thrownTestCanceledException
will returncause.toString
.- cause
a
Throwable
that indicates the cause of the cancellation.
- Exceptions thrown
NullArgumentException
ifcause
isnull
-
def
cancel(message: String, cause: Throwable)(implicit pos: Position): Nothing
Throws
TestCanceledException
, with the passedString
message
as the exception's detail message andThrowable
cause, to indicate a test failed.Throws
TestCanceledException
, with the passedString
message
as the exception's detail message andThrowable
cause, to indicate a test failed.- message
A message describing the failure.
- cause
A
Throwable
that indicates the cause of the failure.
- Exceptions thrown
NullArgumentException
ifmessage
orcause
isnull
-
def
cancel(message: String)(implicit pos: Position): Nothing
Throws
TestCanceledException
, with the passedString
message
as the exception's detail message, to indicate a test was canceled.Throws
TestCanceledException
, with the passedString
message
as the exception's detail message, to indicate a test was canceled.- message
A message describing the cancellation.
- Exceptions thrown
NullArgumentException
ifmessage
isnull
-
def
cancel()(implicit pos: Position): Nothing
Throws
TestCanceledException
to indicate a test was canceled.Throws
TestCanceledException
to indicate a test was canceled. -
def
clone(): AnyRef
- Attributes
- protected[java.lang]
- Definition Classes
- AnyRef
- Annotations
- @throws( ... )
-
def
conversionCheckedConstraint[A, B](implicit equivalenceOfA: Equivalence[A], cnv: (B) ⇒ A): CanEqual[A, B]
- Definition Classes
- TripleEquals → TripleEqualsSupport
-
def
convertEquivalenceToAToBConstraint[A, B](equivalenceOfB: Equivalence[B])(implicit ev: <:<[A, B]): CanEqual[A, B]
- Definition Classes
- TripleEquals → TripleEqualsSupport
-
def
convertEquivalenceToAToBConversionConstraint[A, B](equivalenceOfB: Equivalence[B])(implicit ev: (A) ⇒ B): CanEqual[A, B]
- Definition Classes
- TripleEquals → TripleEqualsSupport
-
def
convertEquivalenceToBToAConstraint[A, B](equivalenceOfA: Equivalence[A])(implicit ev: <:<[B, A]): CanEqual[A, B]
- Definition Classes
- TripleEquals → TripleEqualsSupport
-
def
convertEquivalenceToBToAConversionConstraint[A, B](equivalenceOfA: Equivalence[A])(implicit ev: (B) ⇒ A): CanEqual[A, B]
- Definition Classes
- TripleEquals → TripleEqualsSupport
-
def
convertToCheckingEqualizer[T](left: T): CheckingEqualizer[T]
- Definition Classes
- TripleEquals → TripleEqualsSupport
-
implicit
def
convertToEqualizer[T](left: T): Equalizer[T]
- Definition Classes
- TripleEquals → TripleEqualsSupport
-
def
defaultEquality[A]: Equality[A]
- Definition Classes
- TripleEqualsSupport
-
final
def
eq(arg0: AnyRef): Boolean
- Definition Classes
- AnyRef
-
def
equals(arg0: Any): Boolean
- Definition Classes
- AnyRef → Any
-
def
fail(cause: Throwable)(implicit pos: Position): Nothing
Throws
TestFailedException
, with the passedThrowable
cause, to indicate a test failed.Throws
TestFailedException
, with the passedThrowable
cause, to indicate a test failed. ThegetMessage
method of the thrownTestFailedException
will returncause.toString
.- cause
a
Throwable
that indicates the cause of the failure.
- Exceptions thrown
NullArgumentException
ifcause
isnull
-
def
fail(message: String, cause: Throwable)(implicit pos: Position): Nothing
Throws
TestFailedException
, with the passedString
message
as the exception's detail message andThrowable
cause, to indicate a test failed.Throws
TestFailedException
, with the passedString
message
as the exception's detail message andThrowable
cause, to indicate a test failed.- message
A message describing the failure.
- cause
A
Throwable
that indicates the cause of the failure.
- Exceptions thrown
NullArgumentException
ifmessage
orcause
isnull
-
def
fail(message: String)(implicit pos: Position): Nothing
Throws
TestFailedException
, with the passedString
message
as the exception's detail message, to indicate a test failed.Throws
TestFailedException
, with the passedString
message
as the exception's detail message, to indicate a test failed.- message
A message describing the failure.
- Exceptions thrown
NullArgumentException
ifmessage
isnull
-
def
fail()(implicit pos: Position): Nothing
Throws
TestFailedException
to indicate a test failed.Throws
TestFailedException
to indicate a test failed. -
def
finalize(): Unit
- Attributes
- protected[java.lang]
- Definition Classes
- AnyRef
- Annotations
- @throws( classOf[java.lang.Throwable] )
-
final
def
getClass(): Class[_]
- Definition Classes
- AnyRef → Any
-
def
hashCode(): Int
- Definition Classes
- AnyRef → Any
-
def
intercept[T <: AnyRef](f: ⇒ Any)(implicit classTag: ClassTag[T], pos: Position): T
Intercept and return an exception that's expected to be thrown by the passed function value.
Intercept and return an exception that's expected to be thrown by the passed function value. The thrown exception must be an instance of the type specified by the type parameter of this method. This method invokes the passed function. If the function throws an exception that's an instance of the specified type, this method returns that exception. Else, whether the passed function returns normally or completes abruptly with a different exception, this method throws
TestFailedException
.Note that the type specified as this method's type parameter may represent any subtype of
AnyRef
, not justThrowable
or one of its subclasses. In Scala, exceptions can be caught based on traits they implement, so it may at times make sense to specify a trait that the intercepted exception's class must mix in. If a class instance is passed for a type that could not possibly be used to catch an exception (such asString
, for example), this method will complete abruptly with aTestFailedException
.Also note that the difference between this method and
assertThrows
is that this method returns the expected exception, so it lets you perform further assertions on that exception. By contrast, theassertThrows
method returnsSucceeded
, which means it can serve as the last statement in an async- or safe-style suite.assertThrows
also indicates to the reader of the code that nothing further is expected about the thrown exception other than its type. The recommended usage is to useassertThrows
by default,intercept
only when you need to inspect the caught exception further.- f
the function value that should throw the expected exception
- classTag
an implicit
ClassTag
representing the type of the specified type parameter.- returns
the intercepted exception, if it is of the expected type
- Exceptions thrown
TestFailedException
if the passed function does not complete abruptly with an exception that's an instance of the specified type.
-
final
def
isInstanceOf[T0]: Boolean
- Definition Classes
- Any
-
def
lowPriorityConversionCheckedConstraint[A, B](implicit equivalenceOfB: Equivalence[B], cnv: (A) ⇒ B): CanEqual[A, B]
- Definition Classes
- TripleEquals → TripleEqualsSupport
-
def
lowPriorityTypeCheckedConstraint[A, B](implicit equivalenceOfB: Equivalence[B], ev: <:<[A, B]): CanEqual[A, B]
- Definition Classes
- TripleEquals → TripleEqualsSupport
-
final
def
ne(arg0: AnyRef): Boolean
- Definition Classes
- AnyRef
-
final
def
notify(): Unit
- Definition Classes
- AnyRef
-
final
def
notifyAll(): Unit
- Definition Classes
- AnyRef
-
def
pending: Assertion with PendingStatement
Throws
TestPendingException
to indicate a test is pending.Throws
TestPendingException
to indicate a test is pending.A pending test is one that has been given a name but is not yet implemented. The purpose of pending tests is to facilitate a style of testing in which documentation of behavior is sketched out before tests are written to verify that behavior (and often, the before the behavior of the system being tested is itself implemented). Such sketches form a kind of specification of what tests and functionality to implement later.
To support this style of testing, a test can be given a name that specifies one bit of behavior required by the system being tested. The test can also include some code that sends more information about the behavior to the reporter when the tests run. At the end of the test, it can call method
pending
, which will cause it to complete abruptly withTestPendingException
. Because tests in ScalaTest can be designated as pending withTestPendingException
, both the test name and any information sent to the reporter when running the test can appear in the report of a test run. (In other words, the code of a pending test is executed just like any other test.) However, because the test completes abruptly withTestPendingException
, the test will be reported as pending, to indicate the actual test, and possibly the functionality it is intended to test, has not yet been implemented.Note: This method always completes abruptly with a
TestPendingException
. Thus it always has a side effect. Methods with side effects are usually invoked with parentheses, as inpending()
. This method is defined as a parameterless method, in flagrant contradiction to recommended Scala style, because it forms a kind of DSL for pending tests. It enables tests in suites such asFunSuite
orFunSpec
to be denoted by placing "(pending)
" after the test name, as in:test("that style rules are not laws") (pending)
Readers of the code see "pending" in parentheses, which looks like a little note attached to the test name to indicate it is pending. Whereas "
(pending())
looks more like a method call, "(pending)
" lets readers stay at a higher level, forgetting how it is implemented and just focusing on the intent of the programmer who wrote the code. -
def
pendingUntilFixed(f: ⇒ Unit)(implicit pos: Position): Assertion with PendingStatement
Execute the passed block of code, and if it completes abruptly, throw
TestPendingException
, else throwTestFailedException
.Execute the passed block of code, and if it completes abruptly, throw
TestPendingException
, else throwTestFailedException
.This method can be used to temporarily change a failing test into a pending test in such a way that it will automatically turn back into a failing test once the problem originally causing the test to fail has been fixed. At that point, you need only remove the
pendingUntilFixed
call. In other words, apendingUntilFixed
surrounding a block of code that isn't broken is treated as a test failure. The motivation for this behavior is to encourage people to removependingUntilFixed
calls when there are no longer needed.This method facilitates a style of testing in which tests are written before the code they test. Sometimes you may encounter a test failure that requires more functionality than you want to tackle without writing more tests. In this case you can mark the bit of test code causing the failure with
pendingUntilFixed
. You can then write more tests and functionality that eventually will get your production code to a point where the original test won't fail anymore. At this point the code block marked withpendingUntilFixed
will no longer throw an exception (because the problem has been fixed). This will in turn causependingUntilFixed
to throwTestFailedException
with a detail message explaining you need to go back and remove thependingUntilFixed
call as the problem orginally causing your test code to fail has been fixed.- f
a block of code, which if it completes abruptly, should trigger a
TestPendingException
- Exceptions thrown
TestPendingException
if the passed block of code completes abruptly with anException
orAssertionError
-
final
val
succeed: Assertion
The
Succeeded
singleton.The
Succeeded
singleton.You can use
succeed
to solve a type error when an async test does not end in eitherFuture[Assertion]
orAssertion
. BecauseAssertion
is a type alias forSucceeded.type
, puttingsucceed
at the end of a test body (or at the end of a function being used to map the final future of a test body) will solve the type error. -
final
def
synchronized[T0](arg0: ⇒ T0): T0
- Definition Classes
- AnyRef
-
def
toString(): String
- Definition Classes
- AnyRef → Any
-
def
typeCheckedConstraint[A, B](implicit equivalenceOfA: Equivalence[A], ev: <:<[B, A]): CanEqual[A, B]
- Definition Classes
- TripleEquals → TripleEqualsSupport
-
implicit
def
unconstrainedEquality[A, B](implicit equalityOfA: Equality[A]): CanEqual[A, B]
- Definition Classes
- TripleEquals → TripleEqualsSupport
-
final
def
wait(): Unit
- Definition Classes
- AnyRef
- Annotations
- @throws( ... )
-
final
def
wait(arg0: Long, arg1: Int): Unit
- Definition Classes
- AnyRef
- Annotations
- @throws( ... )
-
final
def
wait(arg0: Long): Unit
- Definition Classes
- AnyRef
- Annotations
- @throws( ... )
-
def
withClue[T](clue: Any)(fun: ⇒ T): T
Executes the block of code passed as the second parameter, and, if it completes abruptly with a
ModifiableMessage
exception, prepends the "clue" string passed as the first parameter to the beginning of the detail message of that thrown exception, then rethrows it.Executes the block of code passed as the second parameter, and, if it completes abruptly with a
ModifiableMessage
exception, prepends the "clue" string passed as the first parameter to the beginning of the detail message of that thrown exception, then rethrows it. If clue does not end in a white space character, one space will be added between it and the existing detail message (unless the detail message is not defined).This method allows you to add more information about what went wrong that will be reported when a test fails. Here's an example:
withClue("(Employee's name was: " + employee.name + ")") { intercept[IllegalArgumentException] { employee.getTask(-1) } }
If an invocation of
intercept
completed abruptly with an exception, the resulting message would be something like:(Employee's name was Bob Jones) Expected IllegalArgumentException to be thrown, but no exception was thrown
- Exceptions thrown
NullArgumentException
if the passedclue
isnull
Deprecated Value Members
-
def
trap[T](f: ⇒ T): Throwable
Trap and return any thrown exception that would normally cause a ScalaTest test to fail, or create and return a new
RuntimeException
indicating no exception is thrown.Trap and return any thrown exception that would normally cause a ScalaTest test to fail, or create and return a new
RuntimeException
indicating no exception is thrown.This method is intended to be used in the Scala interpreter to eliminate large stack traces when trying out ScalaTest assertions and matcher expressions. It is not intended to be used in regular test code. If you want to ensure that a bit of code throws an expected exception, use
intercept
, nottrap
. Here's an example interpreter session withouttrap
:scala> import org.scalatest._ import org.scalatest._ scala> import Matchers._ import Matchers._ scala> val x = 12 a: Int = 12 scala> x shouldEqual 13 org.scalatest.exceptions.TestFailedException: 12 did not equal 13 at org.scalatest.Assertions$class.newAssertionFailedException(Assertions.scala:449) at org.scalatest.Assertions$.newAssertionFailedException(Assertions.scala:1203) at org.scalatest.Assertions$AssertionsHelper.macroAssertTrue(Assertions.scala:417) at .<init>(<console>:15) at .<clinit>(<console>) at .<init>(<console>:7) at .<clinit>(<console>) at $print(<console>) at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39) at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25) at java.lang.reflect.Method.invoke(Method.java:597) at scala.tools.nsc.interpreter.IMain$ReadEvalPrint.call(IMain.scala:731) at scala.tools.nsc.interpreter.IMain$Request.loadAndRun(IMain.scala:980) at scala.tools.nsc.interpreter.IMain.loadAndRunReq$1(IMain.scala:570) at scala.tools.nsc.interpreter.IMain.interpret(IMain.scala:601) at scala.tools.nsc.interpreter.IMain.interpret(IMain.scala:565) at scala.tools.nsc.interpreter.ILoop.reallyInterpret$1(ILoop.scala:745) at scala.tools.nsc.interpreter.ILoop.interpretStartingWith(ILoop.scala:790) at scala.tools.nsc.interpreter.ILoop.command(ILoop.scala:702) at scala.tools.nsc.interpreter.ILoop.processLine$1(ILoop.scala:566) at scala.tools.nsc.interpreter.ILoop.innerLoop$1(ILoop.scala:573) at scala.tools.nsc.interpreter.ILoop.loop(ILoop.scala:576) at scala.tools.nsc.interpreter.ILoop$$anonfun$process$1.apply$mcZ$sp(ILoop.scala:867) at scala.tools.nsc.interpreter.ILoop$$anonfun$process$1.apply(ILoop.scala:822) at scala.tools.nsc.interpreter.ILoop$$anonfun$process$1.apply(ILoop.scala:822) at scala.tools.nsc.util.ScalaClassLoader$.savingContextLoader(ScalaClassLoader.scala:135) at scala.tools.nsc.interpreter.ILoop.process(ILoop.scala:822) at scala.tools.nsc.MainGenericRunner.runTarget$1(MainGenericRunner.scala:83) at scala.tools.nsc.MainGenericRunner.process(MainGenericRunner.scala:96) at scala.tools.nsc.MainGenericRunner$.main(MainGenericRunner.scala:105) at scala.tools.nsc.MainGenericRunner.main(MainGenericRunner.scala)
That's a pretty tall stack trace. Here's what it looks like when you use
trap
:scala> trap { x shouldEqual 13 } res1: Throwable = org.scalatest.exceptions.TestFailedException: 12 did not equal 13
Much less clutter. Bear in mind, however, that if no exception is thrown by the passed block of code, the
trap
method will create a newNormalResult
(a subclass ofThrowable
made for this purpose only) and return that. If the result was theUnit
value, it will simply say that no exception was thrown:scala> trap { x shouldEqual 12 } res2: Throwable = No exception was thrown.
If the passed block of code results in a value other than
Unit
, theNormalResult
'stoString
will print the value:scala> trap { "Dude!" } res3: Throwable = No exception was thrown. Instead, result was: "Dude!"
Although you can access the result value from the
NormalResult
, its type isAny
and therefore not very convenient to use. It is not intended thattrap
be used in test code. The sole intended use case fortrap
is decluttering Scala interpreter sessions by eliminating stack traces when executing assertion and matcher expressions.- Annotations
- @deprecated
- Deprecated
The trap method is no longer needed for demos in the REPL, which now abreviates stack traces, and will be removed in a future version of ScalaTest