Example Custom Jasmine Matchers

README.md

Example Custom Jasmine Matchers

Note: Some matchers require underscore.js and/or jQuery.

General Purpose Matchers

• toHaveElement
• toContainText
• toContainTranslation
• toHaveLength
• toBeA
• toHaveHref

Matchers for Q Promises

• toResolveAs
• toHaveBeenRejectedWith

Acknowledgments

Built at Pivotal Labs

matchers.js

beforeEach(function() {
  function getTranslation(args) {
    var translationKey = args[0];
    var translatedText = t.apply(this, args);
    var missingParams = translatedText.match(/missing (\{\{\w+\}\}) value/);

    if(!I18n.lookup(translationKey)) {
      throw new Error("Test error - Missing translation key '" + translationKey + "'");
    }
    if(missingParams) {
      throw new Error("Test error - Missing parameter for translation key '" + translationKey + "':  " + missingParams[1]);
    }

    return translatedText;
  }

  jasmine.addMatchers({
    toHaveElement: function(selector) {
      return {
        compare: function(view, selector) {
          var result = {pass: false, message: ""};
          result.pass = !!view.$(selector).length;
          if(result.pass) {
            var foundEls = _.map(view.$(selector), function(el) {
              return el.outerHTML;
            });
            result.message = "Expected: " + selector + " not to exist, but found " + foundEls;
          } else {
            result.message = "Expected: " + selector + " to exist, but found no matching elements.";
          }
          return result;
        }
      };
    },

    toContainText: function(expectedText) {
      return {
        compare: function(elementOrString, expectedText) {
          try {
            var actual = _.isString(elementOrString) ? elementOrString : elementOrString.text();
            var result = {pass: false, message: ""};
            result.pass = actual.indexOf(expectedText) > -1;
            if(result.pass) {
              result.message = "Text '" + actual + "' contains '" + expectedText + "'";
            } else {
              result.message = "Expected text '" + actual + "' to contain '" + expectedText + "'";
            }
            return result;
          } catch(e) {
            return {
              pass: false,
              message: e.toString()
            };
          }
        }
      };
    },

    toContainTranslation: function(translationKey) {
      return {
        compare: function(elementOrString, translationKey) {
          var actual = _.isString(elementOrString) ? elementOrString : elementOrString.text();
          var translatedText = getTranslation(_.rest(arguments));
          var result = { pass: actual.indexOf(translatedText) > -1 };
          if(result.pass) {
            result.message = "Expected text '" + actual + "' not to contain the translation for '" + translationKey + "' (" + translatedText + ")";
          } else {
            result.message = "Expected text '" + actual + "' to contain the translation for '" + translationKey + "' (" + translatedText + ")";
          }
          return result;
        }
      };
    },

    toHaveLength: function(expectedLength) {
      return {
        compare: function(actual, expectedLength) {
          var actualLength = _.result(actual, 'length');
          var result = {
            pass: actualLength === expectedLength
          };
          if(result.pass) {
            result.message = "Expected length not to be " + expectedLength;
          } else {
            result.message = "Expected length to be " + expectedLength + ", but got " + actualLength;
          }
          return result;
        }
      };
    },

    toBeA: function(expectedClass) {
      return {
        compare: function(actual, expectedClass) {
          var pass;
          pass = actual instanceof expectedClass || actual.constructor === expectedClass;

          var result = { pass: pass };

          if(result.pass) {
            result.message = "Expected " + jasmine.pp(actual) + " not to be a " + expectedClass;
          } else {
            result.message = "Expected " + jasmine.pp(actual) + " to be a " + jasmine.pp(expectedClass);
          }
          return result;
        }
      };
    },

    toHaveHref: function(expectedHref) {
      return {
        compare: function(actual, expectedHref) {
          var actualHref = actual.attr("href");
          var result = { pass: actualHref === expectedHref };
          if(!actual[0]) {
            throw new Error("Actual element does not exist in toHaveHref");
          }
          var actualHtml = actual[0].outerHTML;
          if(result.pass) {
            result.message = "Expected " + jasmine.pp(actualHtml) + " not to have href " + expectedHref;
          } else {
            result.message = "Expected " + jasmine.pp(actualHtml) + " to have href " + expectedHref;
          }
          return result;
        }
      };
    },

    toResolveAs: function(expectedValue) {
      return {
        compare: function(actual, expectedValue) {
          if(!actual.inspect) { throw new Error("Matcher only works with Q Promises"); }
          var actualValue = actual.inspect().value;
          var result = { pass: actualValue === expectedValue };
          if(result.pass) {
            result.message = "Expected promise not to resolve as " + expectedValue;
          } else {
            result.message = "Expected promise to resolve as " + expectedValue;
          }
          return result;
        }
      };
    },

    toHaveBeenRejectedWith: function(expectedReason) {
      return {
        compare: function(actual, expectedReason) {
          if(!actual.inspect) { throw new Error("Matcher only works with Q Promises"); }
          var actualState = actual.inspect().state;
          var actualReason = actual.inspect().reason;
          var result = { pass: (actualState === 'rejected' && actualReason === expectedReason) };
          if(result.pass) {
            result.message = "Expected promise not to be rejected with '" + expectedReason + "'";
          } else {
            result.message = "Expected promise to be rejected with with '" + expectedReason + "', but was " + actualState + " with '" + actualReason + "'";
          }
          return result;
        }
      };
    }

  });
});