org.scalatest.verbs.MustVerb.scala Maven / Gradle / Ivy

/*
 * Copyright 2001-2013 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.scalatest.verbs

import org.scalactic._

/**
 * Provides an implicit conversion that adds must methods to String
 * to support the syntax of FlatSpec, WordSpec, fixture.FlatSpec,
 * and fixture.WordSpec.
 *
 * 
 * For example, this trait enables syntax such as the following test registration in FlatSpec
 * and fixture.FlatSpec:
 * 
 *
 *  * "A Stack (when empty)" must "be empty" in { ... }
 *                        ^
 * 
 *
 * 
 * It also enables syntax such as the following shared test registration in FlatSpec
 * and fixture.FlatSpec:
 * 
 *
 *  * "A Stack (with one item)" must behave like nonEmptyStack(stackWithOneItem, lastValuePushed)
 *                           ^
 * 
 *
 * 
 * In addition, it supports the registration of subject descriptions in WordSpec
 * and fixture.WordSpec, such as:
 * 
 *
 *  * "A Stack (when empty)" must { ...
 *                        ^
 * 
 *
 * 
 * And finally, it also supportds the registration of subject descriptions with after words
 * in WordSpec and fixture.WordSpec. For example:
 * 
 *
 *  *    def provide = afterWord("provide")
 *
 *   "The ScalaTest Matchers DSL" must provide {
 *                                ^
 * 
 *
 * 
 * The reason this implicit conversion is provided in a separate trait, instead of being provided
 * directly in FlatSpec, WordSpec, fixture.FlatSpec, and
 * fixture.WordSpec, is because an implicit conversion provided directly would conflict
 * with the implicit conversion that provides must methods on String
 * in the MustMatchers trait. By contrast, there is no conflict with
 * the separate MustVerb trait approach, because:
 * 
 *
 * 
 * FlatSpec, WordSpec, fixture.FlatSpec, and fixture.WordSpec
 * mix in MustVerb directly, and
 * MustMatchers extends MustVerb, overriding the
 * convertToStringMustWrapper implicit conversion function.
 * 
 *
 * 
 * So whether or not
 * a FlatSpec, WordSpec, fixture.FlatSpec, or fixture.WordSpec
 * mixes in MustMatchers, there will only be one
 * implicit conversion in scope that adds must methods to Strings.
 * 
 *
 * 
 * Also, because the class of the result of the overriding convertToStringMustWrapper
 * implicit conversion method provided in MustMatchers extends this trait's
 * StringMustWrapperForVerb class, the four uses of must provided here
 * are still available. These four must are in fact available to any class
 * that mixes in MustMatchers, but each takes an implicit parameter that is provided
 * only in FlatSpec and fixture.FlatSpec, or WordSpec and
 * fixture.WordSpec.  
 * 
 *
 * @author Bill Venners
 */
trait MustVerb {

  /**
   * This class supports the syntax of FlatSpec, WordSpec, fixture.FlatSpec,
   * and fixture.WordSpec.
   *
   * 
   * This class is used in conjunction with an implicit conversion to enable must methods to
   * be invoked on Strings.
   * 
   *
   * @author Bill Venners
   */
  trait StringMustWrapperForVerb {

    val leftSideString: String

    val pos: source.Position

    /**
     * Supports test registration in FlatSpec and fixture.FlatSpec.
     *
     * 
     * For example, this method enables syntax such as the following in FlatSpec
     * and fixture.FlatSpec:
     * 
     *
     *      * "A Stack (when empty)" must "be empty" in { ... }
     *                        ^
     * 
     *
     * 
     * FlatSpec passes in a function via the implicit parameter that takes
     * three strings and results in a ResultOfStringPassedToVerb. This method
     * simply invokes this function, passing in leftSideString, the verb string
     * "must", and right, and returns the result.
     * 
     */
    def must(right: String)(implicit svsi: StringVerbStringInvocation): ResultOfStringPassedToVerb = {
      svsi(leftSideString, "must", right, pos)
    }

    /**
     * Supports shared test registration in FlatSpec and fixture.FlatSpec.
     *
     * 
     * For example, this method enables syntax such as the following in FlatSpec
     * and fixture.FlatSpec:
     * 
     *
     *      * "A Stack (with one item)" must behave like nonEmptyStack(stackWithOneItem, lastValuePushed)
     *                           ^
     * 
     *
     * 
     * FlatSpec and fixture.FlatSpec passes in a function via the implicit parameter that takes
     * a string and results in a BehaveWord. This method
     * simply invokes this function, passing in leftSideString, and returns the result.
     * 
     */
    def must(right: BehaveWord)(implicit svbli: StringVerbBehaveLikeInvocation): BehaveWord = {
      svbli(leftSideString, pos)
    }

    /**
     * Supports the registration of subject descriptions in WordSpec
     * and fixture.WordSpec.
     *
     * 
     * For example, this method enables syntax such as the following in WordSpec
     * and fixture.WordSpec:
     * 
     *
     *      * "A Stack (when empty)" must { ...
     *                        ^
     * 
     *
     * 
     * WordSpec passes in a function via the implicit parameter of type StringVerbBlockRegistration,
     * a function that takes two strings and a no-arg function and results in Unit. This method
     * simply invokes this function, passing in leftSideString, the verb string
     * "must", and the right by-name parameter transformed into a
     * no-arg function.
     * 
     */
    def must(right: => Unit)(implicit fun: StringVerbBlockRegistration): Unit = {
      fun(leftSideString, "must", pos, () => right)
    }

    /**
     * Supports the registration of subject descriptions with after words
     * in WordSpec and fixture.WordSpec.
     *
     * 
     * For example, this method enables syntax such as the following in WordSpec
     * and fixture.WordSpec:
     * 
     *
     *      *    def provide = afterWord("provide")
     *
     *   "The ScalaTest Matchers DSL" must provide {
     *                                ^
     * 
     *
     * 
     * WordSpec passes in a function via the implicit parameter that takes
     * two strings and a ResultOfAfterWordApplication and results in Unit. This method
     * simply invokes this function, passing in leftSideString, the verb string
     * "must", and the ResultOfAfterWordApplication passed to must.
     * 
     */
    def must(resultOfAfterWordApplication: ResultOfAfterWordApplication)(implicit swawr: SubjectWithAfterWordRegistration): Unit = {
      swawr(leftSideString, "must", resultOfAfterWordApplication, pos)
    }
  }

  import scala.language.implicitConversions

  /**
   * Implicitly converts an object of type String to a StringMustWrapper,
   * to enable must methods to be invokable on that object.
   */
  implicit def convertToStringMustWrapperForVerb(o: String)(implicit position: source.Position): StringMustWrapperForVerb =
    new StringMustWrapperForVerb {
      val leftSideString = o.trim
      val pos = position
    }
}