public class ExampleSuite extends Suite {
    public function ExampleSuite() {
    }
    override protected function addSpecs():void {
        add(new ExampleSpec());
    }
}

public class ExampleSpec extends Spec {

    public function ExampleSpec() {
        super("Example"); //described entity
    }

    override protected function describe():void {
        //dealing with errors
        claim("Spec catches errors").so.calling(raise).shouldThrowError();
        claim("Spec catches errors with specific messages").so.callingWithParams(raise, "a").shouldThrowError("a");
        claim("Spec detects not throwing").so.calling(echo).shouldNotThrowError();
        claim("Spec catches errors with specific messages").so.callingWithParams(raise, "b").shouldNotThrowError("a");
        
        //dealing with returned values of passed functions
        claim("Spec with values, returned by functions").so.callingWithParams(echo, 1).returnedValue.shouldBeEqual(1);
        
        //comparisons
        claim("Spec compares values").so.value(1).shouldBeEqual(1);
        claim("More comparisons").so.value(1).shouldBeLessOrEqual(1);
        claim("More comparisons").so.value(1).shouldBeLessOrEqual(2);
        claim("More comparisons").so.value(1).shouldBeLessThan(2);
        claim("More comparisons").so.value(1).shouldBeMoreThan(0);
        claim("More comparisons").so.value(1).shouldBeMoreOrEqual(0);
        claim("More comparisons").so.value(1).shouldBeMoreOrEqual(1);
        claim("More comparisons").so.value(1).shouldBeEqual(1);
        claim("More comparisons").so.value(1).shouldNotBeEqual(2);
        claim("More comparisons").so.value(1).shouldNotBeNull;
        claim("More comparisons").so.value(null).shouldBeNull;
        
        //logical statements
        claim("Simple And").so.value(false).shouldBeEqual(false).and.value(true).shouldBeEqual(true);
        claim("Simple Or").so.value(false).shouldBeEqual(true).or.value(true).shouldBeEqual(true);
        claim("Complex logic").so.value(true).shouldBeEqual(false).or.value(1).shouldBeMoreOrEqual(-4).and.calling(raise).shouldThrowError();
    }

    private static function echo(value:* = null):* {
        return value;
    }

    private static function raise(message:String = ""):void {
        throw new Error(message);
    }
}

[trace]    [info] Example:
[trace] [success] - Spec catches errors
[trace] [success] - Spec catches errors with specific messages
[trace] [success] - Spec detects not throwing
[trace] [success] - Spec catches errors with specific messages
[trace] [success] - Spec compares values
[trace] [success] - Spec with values, returned by functions
[trace] [success] - More comparisons
[trace] [success] - More comparisons
[trace] [success] - More comparisons
[trace] [success] - More comparisons
[trace] [success] - More comparisons
[trace] [success] - More comparisons
[trace] [success] - More comparisons
[trace] [success] - More comparisons
[trace] [success] - More comparisons
[trace] [success] - More comparisons
[trace] [success] - Simple And
[trace] [success] - Simple Or
[trace] [success] - Complex logic
[trace]    [info]
[trace] [success] Total claims: 19. Successful: 19, failed: 0

override protected function init():void {
    /**
    * Your custom logger, must implement ISpecLogger. 
    * Default logger is instance of TraceSpecLogger class
    */
    setSpecLogger(new MyCustomSpecLogger()); 
    /**
    * By default only failed statements params are printed.
    * You can print them all.
    */
    printAll = true;
}

[trace]    [info] Example:
[trace] [success] - Spec catches errors
[trace] [success]   [function should throw (success)]
[trace] [success] - Spec catches errors with specific messages
[trace] [success]   [function should throw error with message "a" (success)]
[trace] [success] - Spec detects not throwing
[trace] [success]   [function should not throw (success)]
[trace] [success] - Spec catches errors with specific messages
[trace] [success]   [function should not throw error with message "a", message was "b" (success)]
[trace] [success] - Spec compares values
[trace] [success]   [1 is equal 1 (success)]
[trace] [success] - Spec with values, returned by functions
[trace] [success]   [function should not throw (success)] AND [1 is equal 1 (success)]
[trace] [success] - More comparisons
[trace] [success]   [1 should be less or equal 1 (success)]
[trace] [success] - More comparisons
[trace] [success]   [1 should be less or equal 2 (success)]
[trace] [success] - More comparisons
[trace] [success]   [1 should be less than 2 (success)]
[trace] [success] - More comparisons
[trace] [success]   [1 should be more than 0 (success)]
[trace] [success] - More comparisons
[trace] [success]   [1 should be more or equal 0 (success)]
[trace] [success] - More comparisons
[trace] [success]   [1 should be more or equal 1 (success)]
[trace] [success] - More comparisons
[trace] [success]   [1 is equal 1 (success)]
[trace] [success] - More comparisons
[trace] [success]   [1 is not equal 2 (success)]
[trace] [success] - More comparisons
[trace] [success]   [1 is not equal null (success)]
[trace] [success] - More comparisons
[trace] [success]   [null is equal null (success)]
[trace] [success] - Simple And
[trace] [success]   [false is equal false (success)] AND [true is equal true (success)]
[trace] [success] - Simple Or
[trace] [success]   [false is equal true (fail)] OR [true is equal true (success)]
[trace] [success] - Complex logic
[trace] [success]   [true is equal false (fail)] OR [1 should be more or equal -4 (success)] AND [function should throw (success)]
[trace]    [info]
[trace] [success] Total claims: 19. Successful: 19, failed: 0

[trace]    [info] Example:
[trace] [success] - one claim
[trace]    [fail] - other claim fails because of:
[trace]    [fail]   [function should throw error with message "expected message", message was: "not expected message" (fail)]
[trace]    [info]
[trace]    [fail] Total claims: 2. Successful: 1, failed: 1

claim("my function is fast").so.calling(heavyCalculations).executionTime.shouldBeLessOrEqual(1);