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DurationConstraint Item

..  cpp:class:: DurationConstraint

    Checks the time between two signal occurrences.


..  cpp:namespace:: DurationConstraint
Inherits::qml:item:`Component`
Properties::cpp:member:`beginOn`, :cpp:member:`duration`, :cpp:member:`enabled` :cpp:member:`endOn`, :cpp:member:`evaluateOnFinished`, :cpp:member:`evaluateOnValidation`, :cpp:member:`maxDuration`, :cpp:member:`minDuration`. :cpp:member:`timedOut`, :cpp:member:`valid`
Methods::cpp:func:`begin()`, :cpp:func:`end()`

Detailed Description

..  cpp:namespace:: DurationConstraint

DurationConstraint measures the time between two signals :cpp:member:`beginOn` and :cpp:member:`endOn`. The methods :cpp:func:`begin()` or :cpp:func:`end()` may be used as an alternative if no signals are available. The expected duration is configured with :cpp:member:`minDuration` and :cpp:member:`maxDuration`.

The constraint has two stages: validation and evaluation. Validation happens immediately after the :cpp:member:`endOn` signal has fired. In the same moment, the :cpp:member:`duration` property is updated and shows the measured duration. Whether the duration is within the expected range, can be seen at the property :cpp:member:`valid`.

During the evaluation stage, it is decided whether the test case is aborted. Evaluation can either happen immediately after validation (:cpp:member:`evaluateOnValidation` is true) or just before the :cpp:func:`Testcase::finished` event (:cpp:member:`evaluateOnFinished` is true). The :cpp:member:`enabled` property switches measurement completely on and off.

Example for measuring the duration between two signals:

import qst 1.0

Testcase {

    ProcessProbe {
        id: process
        command: "sleep"
        arguments: [ 3 ]
    }

    DurationConstraint {
        id: constraint
        minDuration: 2.9
        maxDuration: 3.1

        beginOn: process.started
        endOn: process.finished
    }

    function run() {
        process.start()
        Qst.wait(4000)
    }

Example for monitoring a sequence of actions:

import qst 1.0

Testcase {

    DurationConstraint {
        id: constraint
        minDuration: 5
        maxDuration: 10
    }

    function run() {
        constraint.begin()

        // Now do something very time consuming...
        Qst.wait(20); // will be aborted because constraint
                      // is violated after 10 ms.
    }

Properties

..  cpp:member:: signal beginOn

    :default: undefined

    Starts a measurement action. This property must either be QML signal or an
    object that defines a ``connect()`` method with a signal handler as
    parameter. When updating this property, the old signal will be disconnected.

    See also: :cpp:member:`endOn`, :cpp:func:`begin()`, :cpp:func:`end()`



..  cpp:member:: double duration

    :default: 0.0

    The measured timed between :cpp:member:`beginOn` and :cpp:member:`endOn`.



..  cpp:member:: bool enabled

    :default: ``true``

    When ``false``, the signals :cpp:member:`beginOn` and :cpp:member:`endOn` do
    not have any effect and the constraint is neither validated nor evaluated.



..  cpp:member:: signal endOn

    :default: undefined

    Ends a measurement cycle and triggers validation. This property must either
    be QML signal or an object that defines a ``connect()`` method with a signal
    handler as parameter. When updating this property, the old signal will be
    disconnected.

    See also: :cpp:member:`beginOn`, :cpp:func:`begin()`, :cpp:func:`end()`



..  cpp:member:: bool evaluateOnFinished

    :default: false

    If ``true``, the constraint will be evaluated by `Qst` just before
    :cpp:func:`Testcase::finished()`.

    See also :cpp:member:`evaluateOnValidation`



..  cpp:member:: bool evaluateOnValidation

    :default: true

    If ``true``, the test case will fail immediately when validation fails.  If
    ``false``, then the constraint will not be evaluated immediately. Instead,
    it will be evaluated on :cpp:func:`Testcase::finished()`.

    See also :cpp:member:`evaluateOnFinished`



..  cpp:member:: double maxDuration

    :default: 0.0

    Specifies the maximum allowed time between :cpp:member:`beginOn` and
    :cpp:member:`endOn`. The value must be greater or equal
    :cpp:member:`minDuration`.


    See also :cpp:member:`minDuration`



..  cpp:member:: double minDuration

    :default: 0.0

    Specifies the minimum allowed time between :cpp:member:`beginOn` and
    :cpp:member:`endOn`. The value must be less or equal
    :cpp:member:`maxDuration`.

    See also :cpp:member:`maxDuration`



..  cpp:member:: bool timedOut

    :default: false

    Becomes ``true`` when the time between :cpp:member:`beginOn` and
    :cpp:member:`endOn` exceeds the specified duration range. This property is
    set back to ``false`` on each measurement interval.



..  cpp:member:: bool valid

    :default: false

    Reflects whether :cpp:member:`duration` is within the specified range.

Methods

..  cpp:function:: void begin()

    Equivalent to :cpp:member:`beginOn`. Can be used to start a measurement
    manually or when no signal is available to attach to.

    See also: :cpp:func:`end()`, :cpp:member:`beginOn`, :cpp:member:`endOn`



..  cpp:function:: void end()

    Equivalent to :cpp:member:`beginOn`. Can be used to start a measurement
    manually or when no signal is available to attach to.

    See also: :cpp:func:`begin()`, :cpp:member:`beginOn`, :cpp:member:`endOn`