A Tiny Framework for Automated Tests in Google Apps Script

framework.js

function allTests(thisFnWrapsAllYourTests) {
  var successes = 0;
  var failures = [];
  var scopes = [];

  var msgInScope = function(msg) {
    return scopes.concat([msg]).join(": ");
  }

  var doTheseListsMatch = function(expected, actual) {
    if (expected.length != actual.length) {
      return false;
    }

    for (var i = 0; i < expected.length; i++) {
      if (expected[i].constructor === Array && actual[i].constructor === Array) {
        if (!doTheseListsMatch(expected[i], actual[i])) {
          return false;
        }
      }
      else if (expected[i] !== actual[i]) {
        return false;
      }
    }
    return true;
  }

  function runTestAndRecordResult(message, fn) {
    try {
      if (fn()) {
        successes += 1;
      } else {
        failures.push(msgInScope(message));
      }
    }
    catch(x) {
      failures.push(msgInScope(x));
    }
  }

  thisFnWrapsAllYourTests({
    describe: function(blockName, thisFnWrapsOneTest) {
      scopes.push(blockName);
      thisFnWrapsOneTest();
      scopes.pop();
    },

    listMatch: function(expected, actual) {
      runTestAndRecordResult("Expected " + expected + ", got " + actual + ".", function() {
        return doTheseListsMatch(expected, actual);
      });
    },

    areEqual: function(expected, actual) {
      runTestAndRecordResult("Expected " + expected.constructor.name + " " + expected + ", got " + actual.constructor.name + " " + actual + ".", function() {
        return expected === actual;
      });
    },

    areClose: function(expected, actual, epsilon) {
      if (epsilon === undefined) {
        epsilon = 0.001;
      }
      runTestAndRecordResult("Expected " + expected + " (+/- " + epsilon + "), got " + actual + ".", function() {
        return Math.abs(expected - actual) <= epsilon;
      });
    }
  });

  var totalTests = successes + failures.length;
  alert(successes + " of " + totalTests + " tests passed.\n" + failures.length + " failures.\n" + failures.join("\n"));
}

your-code.js

function add(a, b) {
  return a + b;
}
function sum(numbers) {
  var sum = 0;
  for (var i = 0; i < numbers.length; i++) {
    sum += numbers[i];
  }
  return sum;
}

your-tests.js

// This would probably be wired up to a menu item in a Google Spreadsheet:
function runAllTestsFromTheMenu_() {
  allTests(function(t) {
    t.describe("basic tests", function() {
      t.areEqual(1, 1);
    });

    t.describe("simple functions", function() {
      t.describe("add", function() {
        t.areEqual(3, add(1, 2));
        t.areEqual(7, add(0, 7));
        t.areEqual(1, add(10, -9));
      });

      t.describe("sum", function() {
        t.areEqual(10, sum([1,2,3,4]));
        t.areEqual(90, sum([20, 30, 40]));
        t.areEqual(0, sum([0, -50, 20, 30]));
      });
    });
  });
}