org.scalautils.LegacyEqualizer.scala Maven / Gradle / Ivy
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/*
* Copyright 2001-2008 Artima, Inc.
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package org.scalautils
/**
* Class used via an implicit conversion to enable any two objects to be compared with
* === in assertions in tests. For example:
*
*
* assert(a === b)
*
*
*
* The benefit of using assert(a === b) rather than assert(a == b) is
* that a TestFailedException produced by the former will include the values of a and b
* in its detail message.
* The implicit method that performs the conversion from Any to Equalizer is
* convertToEqualizer in trait Assertions.
*
*
*
* In case you're not familiar with how implicit conversions work in Scala, here's a quick explanation.
* The convertToEqualizer method in Assertions is defined as an "implicit" method that takes an
* Any, which means you can pass in any object, and it will convert it to an Equalizer.
* The Equalizer has === defined. Most objects don't have === defined as a method
* on them. Take two Strings, for example:
*
*
*
* assert("hello" === "world")
*
*
*
* Given this code, the Scala compiler looks for an === method on class String, because that's the class of
* "hello". String doesn't define ===, so the compiler looks for an implicit conversion from
* String to something that does have an === method, and it finds the convertToEqualizer method. It
* then rewrites the code to this:
*
*
*
* assert(convertToEqualizer("hello").===("world"))
*
*
*
* So inside a Suite (which mixes in Assertions, === 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 to Equalizer. The left
* value may be a null reference, because this is allowed by Scala's == operator.
*
*
* @param left An object to convert to Equalizer, which represents the left value
* of an assertion.
*
* @author Bill Venners
*/
class LegacyEqualizer[L](left: L) {
private def diffStrings(s: String, t: String): Tuple2[String, String] = {
def findCommonPrefixLength(s: String, t: String): Int = {
val max = s.length.min(t.length) // the maximum potential size of the prefix
var i = 0
var found = false
while (i < max & !found) {
found = (s.charAt(i) != t.charAt(i))
if (!found)
i = i + 1
}
i
}
def findCommonSuffixLength(s: String, t: String): Int = {
val max = s.length.min(t.length) // the maximum potential size of the suffix
var i = 0
var found = false
while (i < max & !found) {
found = (s.charAt(s.length - 1 - i) != t.charAt(t.length - 1 - i))
if (!found)
i = i + 1
}
i
}
val commonPrefixLength = findCommonPrefixLength(s, t)
val commonSuffixLength = findCommonSuffixLength(s.substring(commonPrefixLength), t.substring(commonPrefixLength))
val prefix = s.substring(0, commonPrefixLength)
val suffix = if (s.length - commonSuffixLength < 0) "" else s.substring(s.length - commonSuffixLength)
val sMiddleEnd = s.length - commonSuffixLength
val tMiddleEnd = t.length - commonSuffixLength
val sMiddle = s.substring(commonPrefixLength, sMiddleEnd)
val tMiddle = t.substring(commonPrefixLength, tMiddleEnd)
val MaxContext = 20
val shortPrefix = if (commonPrefixLength > MaxContext) "..." + prefix.substring(prefix.length - MaxContext) else prefix
val shortSuffix = if (commonSuffixLength > MaxContext) suffix.substring(0, MaxContext) + "..." else suffix
(shortPrefix + "[" + sMiddle + "]" + shortSuffix, shortPrefix + "[" + tMiddle + "]" + shortSuffix)
}
// If the objects are two strings, replace them with whatever is returned by diffStrings.
// Otherwise, use the same objects.
def getObjectsForFailureMessage(a: Any, b: Any) =
a match {
case aStr: String => {
b match {
case bStr: String => {
diffStrings(aStr, bStr)
}
case _ => (a, b)
}
}
case _ => (a, b)
}
def ===(right: Any)(implicit equality: Equality[L]): Option[String] =
if (equality.areEqual(left, right))
None
else {
val (leftee, rightee) = getObjectsForFailureMessage(left, right)
Some(FailureMessages("didNotEqual", leftee, rightee))
}
def !==(right: Any)(implicit equality: Equality[L]): Option[String] =
if (!equality.areEqual(left, right))
None
else {
val (leftee, rightee) = getObjectsForFailureMessage(left, right)
Some(FailureMessages("equaled", leftee, rightee))
}
/*
def ===(interval: Interval[L]): Option[String] =
if (if (interval != null) interval.isWithin(left) else left == interval)
None
else
Some(FailureMessages("wasNotPlusOrMinus", left, interval.right, interval.tolerance))
def !==(interval: Interval[L]): Option[String] =
if (if (interval != null) !interval.isWithin(left) else left != interval)
None
else
Some(FailureMessages("wasPlusOrMinus", left, interval.right, interval.tolerance))
*/
def ===(interval: Interval[L]): Option[String] =
if (interval == null) {
if (left == null)
None
else {
val (leftee, rightee) = getObjectsForFailureMessage(left, interval)
Some(FailureMessages("equaled", leftee, rightee))
}
}
else {
if (interval.isWithin(left))
None
else
Some(FailureMessages("wasNotPlusOrMinus", left, interval.right, interval.tolerance))
}
def !==(interval: Interval[L]): Option[String] =
if (interval == null) {
if (left != null)
None
else {
val (leftee, rightee) = getObjectsForFailureMessage(left, interval)
Some(FailureMessages("equaled", leftee, rightee))
}
}
else {
if (if (interval != null) !interval.isWithin(left) else left != interval)
None
else
Some(FailureMessages("wasPlusOrMinus", left, interval.right, interval.tolerance))
}
}