org.scalatest.junit

AssertionsForJUnit

trait AssertionsForJUnit extends Assertions

Trait that contains ScalaTest's basic assertion methods, suitable for use with JUnit.

The assertion methods provided in this trait look and behave exactly like the ones in Assertions, except instead of throwing TestFailedException they throw JUnitTestFailedError, which extends junit.framework.AssertionFailedError.

JUnit 3 (release 3.8 and earlier) distinguishes between failures and errors. If a test fails because of a failed assertion, that is considered a failure. If a test fails for any other reason, either the test code or the application being tested threw an unexpected exception, that is considered an error. The way JUnit 3 decides whether an exception represents a failure or error is that only thrown junit.framework.AssertionFailedErrors are considered failures. Any other exception type is considered an error. The exception type thrown by the JUnit 3 assertion methods declared in junit.framework.Assert (such as assertEquals, assertTrue, and fail) is, therefore, AssertionFailedError.

In JUnit 4, AssertionFailedError was made to extend java.lang.AssertionError, and the distinction between failures and errors was essentially dropped. However, some tools that integrate with JUnit carry on this distinction, so even if you are using JUnit 4 you may want to use this AssertionsForJUnit trait instead of plain-old ScalaTest Assertions.

To use this trait in a JUnit 3 TestCase, you can mix it into your TestCase class, like this:

import junit.framework.TestCase
import org.scalatest.junit.AssertionsForJUnit

class MyTestCase extends TestCase with AssertionsForJUnit {

def testSomething() { assert("hi".charAt(1) === 'i') }

// ... }

You can alternatively import the methods defined in this trait.

import junit.framework.TestCase
import org.scalatest.junit.AssertionsForJUnit._

class MyTestCase extends TestCase {

def testSomething() { assert("hi".charAt(1) === 'i') }

// ... }

For details on the importing approach, see the documentation for the AssertionsForJUnit companion object. For the details on the AssertionsForJUnit syntax, see the Scaladoc documentation for org.scalatest.Assertions

known subclasses: ShouldMatchersForJUnit, MustMatchersForJUnit, JUnitSuite, JUnit3Suite, AssertionsForJUnit
Go to: companion

Inherits

  1. Assertions
  2. AnyRef
  3. Any

Type Members

  1. class Equalizer extends AnyRef

    Class used via an implicit conversion to enable any two objects to be compared with === in assertions in tests

Value Members

  1. def assert(o: Option[String]): Unit

    Assert that an Option[String] is None

    Assert that an Option[String] is None. If the condition is None, this method returns normally. Else, it throws TestFailedException with the String value of the Some included in the TestFailedException's detail message.

    This form of assert is usually called in conjunction with an implicit conversion to Equalizer, using a === comparison, as in:

    assert(a === b)
    

    For more information on how this mechanism works, see the documentation for Equalizer.

    o

    the Option[String] to assert

    definition classes: Assertions
    Go to: companion
  2. def assert(o: Option[String], clue: Any): Unit

    Assert that an Option[String] is None

    Assert that an Option[String] is None. If the condition is None, this method returns normally. Else, it throws TestFailedException with the String value of the Some, as well as the String obtained by invoking toString on the specified message, included in the TestFailedException's detail message.

    This form of assert is usually called in conjunction with an implicit conversion to Equalizer, using a === comparison, as in:

    assert(a === b, "extra info reported if assertion fails")
    

    For more information on how this mechanism works, see the documentation for Equalizer.

    o

    the Option[String] to assert

    clue

    An objects whose toString method returns a message to include in a failure report.

    definition classes: Assertions
    Go to: companion
  3. def assert(condition: Boolean, clue: Any): Unit

    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 is true, this method returns normally. Else, it throws TestFailedException with the String obtained by invoking toString on the specified message as the exception's detail message.

    condition

    the boolean condition to assert

    clue

    An objects whose toString method returns a message to include in a failure report.

    definition classes: Assertions
    Go to: companion
  4. def assert(condition: Boolean): Unit

    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 throws TestFailedException.

    condition

    the boolean condition to assert

    definition classes: Assertions
    Go to: companion
  5. def convertToEqualizer(left: Any): Equalizer

    Implicit conversion from Any to Equalizer, used to enable assertions with === comparisons

    Implicit conversion from Any to Equalizer, used to enable assertions with === comparisons.

    For more information on this mechanism, see the documentation for Equalizer.

    Because trait Suite mixes in Assertions, this implicit conversion will always be available by default in ScalaTest Suites. This is the only implicit conversion that is in scope by default in every ScalaTest Suite. Other implicit conversions offered by ScalaTest, such as those that support the matchers DSL or invokePrivate, must be explicitly invited into your test code, either by mixing in a trait or importing the members of its companion object. The reason ScalaTest requires you to invite in implicit conversions (with the exception of the implicit conversion for === operator) is because if one of ScalaTest's implicit conversions clashes with an implicit conversion used in the code you are trying to test, your program won't compile. Thus there is a chance that if you are ever trying to use a library or test some code that also offers an implicit conversion involving a === operator, you could run into the problem of a compiler error due to an ambiguous implicit conversion. If that happens, you can turn off the implicit conversion offered by this convertToEqualizer method simply by overriding the method in your Suite subclass, but not marking it as implicit:

    // In your Suite subclass
    override def convertToEqualizer(left: Any) = new Equalizer(left)
    

    left

    the object whose type to convert to Equalizer.

    attributes: implicit
    definition classes: Assertions
    Go to: companion
  6. def equals(arg0: Any): Boolean

    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:

    • It is reflexive: for any instance x of type Any, x.equals(x) should return true.
    • It is symmetric: for any instances x and y of type Any, x.equals(y) should return true if and only if y.equals(x) returns true.
    • It is transitive: for any instances 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)).

    arg0

    the object to compare against this object for equality.

    returns

    true if the receiver object is equivalent to the argument; false otherwise.

    definition classes: AnyRef ⇐ Any
    Go to: companion
  7. def expect(expected: Any)(actual: Any): Unit

    Expect that the value passed as expected equals the value passed as actual

    Expect that the value passed as expected equals the value passed as actual. If the actual value equals the expected value (as determined by ==), expect returns normally. Else, expect throws an TestFailedException whose detail message includes the expected and actual values.

    expected

    the expected value

    actual

    the actual value, which should equal the passed expected value

    definition classes: Assertions
    Go to: companion
  8. def expect(expected: Any, clue: Any)(actual: Any): Unit

    Expect that the value passed as expected equals the value passed as actual

    Expect that the value passed as expected equals the value passed as actual. If the actual equals the expected (as determined by ==), expect returns normally. Else, if actual is not equal to expected, expect throws an TestFailedException whose detail message includes the expected and actual values, as well as the String obtained by invoking toString on the passed message.

    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

    definition classes: Assertions
    Go to: companion
  9. def fail(cause: Throwable): Nothing

    Throws TestFailedException, with the passed Throwable cause, to indicate a test failed

    Throws TestFailedException, with the passed Throwable cause, to indicate a test failed. The getMessage method of the thrown TestFailedException will return cause.toString().

    cause

    a Throwable that indicates the cause of the failure.

    definition classes: Assertions
    Go to: companion
  10. def fail(message: String, cause: Throwable): Nothing

    Throws TestFailedException, with the passed String message as the exception's detail message and Throwable cause, to indicate a test failed

    Throws TestFailedException, with the passed String message as the exception's detail message and Throwable cause, to indicate a test failed.

    message

    A message describing the failure.

    cause

    A Throwable that indicates the cause of the failure.

    definition classes: Assertions
    Go to: companion
  11. def fail(message: String): Nothing

    Throws TestFailedException, with the passed String message as the exception's detail message, to indicate a test failed

    Throws TestFailedException, with the passed String message as the exception's detail message, to indicate a test failed.

    message

    A message describing the failure.

    definition classes: Assertions
    Go to: companion
  12. def fail(): Nothing

    Throws TestFailedException to indicate a test failed

    Throws TestFailedException to indicate a test failed.

    definition classes: Assertions
    Go to: companion
  13. def hashCode(): Int

    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.

    definition classes: AnyRef ⇐ Any
    Go to: companion
  14. def intercept[T <: AnyRef](f: ⇒ Any)(manifest: Manifest[T]): 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 just Throwable 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 as String, for example), this method will complete abruptly with a TestFailedException.

    f

    the function value that should throw the expected exception

    manifest

    an implicit Manifest representing the type of the specified type parameter.

    returns

    the intercepted exception, if it is of the expected type

    definition classes: Assertions
    Go to: companion
  15. def toString(): String

    Returns a string representation of the object

    Returns a string representation of the object.

    The default representation is platform dependent.

    definition classes: AnyRef ⇐ Any
    Go to: companion