# Preview / Testing

## 👁️ What is the preview / testing center

The preview testing center allows you to fully test out all your survey questions, answers and all their [logic](/form-management/form-designer/questions/question-properties/skip-hide-logic.md) before [going live](/form-management/publish-deploy.md) with real [respondents](/form-management/respondents-management.md). 

The testing center can be divided in following sections.

![](/files/-MBs-QWJXsTZryD0f-IW)

1. The **device target** let you preview how your survey will look on various devices and screen sizes. Note that while very close to the real device this is only a simulation its not an exact 1 to 1 result of what you would get on a real device.
2. The **page navigator** let you select and switch quickly to any page of your survey. If you survey is set as a [single question flow](/form-management/form-designer/form-settings/single-question-flow.md) survey you will be able to navigate through the questions instead of pages.
3. The **preview testing properties** let you define all the testing tool properties.
4. Enter custom name / value pairs that will be used as a virtual **query string** during testing.
5. **Loads up a** [**panelist**](/panels/panelists.md) from one of your [panel](/panels.md), this feature is very handy if your survey relies on panelists for its display through [piping](/form-management/form-designer/piping/text-data-piping.md) or for some of its [logic](/form-management/form-designer/questions/question-properties/skip-hide-logic.md)
6. On the right you will find the **main survey preview** screen, you can use it to take your survey as a respondent. Note however that no answers will be saved when submitting the test survey.

## 🔅 Preview / testing properties

* **`Generate a prefilled answers url`** generates a [deployment link](/form-management/publish-deploy/web.md) that includes the answers that you have selected or entered to pre-fill the survey when the respondents takes it through that generated link. 
* **`Keep last opened page`** keeps the last opened page if you leave the test center and reload it later on. 
* **`Keep test answers`** keeps all the answers you have selected or entered when leaving the test center and reloads them once you reload the test center. 
* **`Disable validation`** runs the survey without any validation checks like mandatory questions checks.
* **`Show skipped / hidden answers`**  force display of the  question / answers that have been [hidden / skipped](/form-management/form-designer/questions/question-properties/skip-hide-logic.md). Hidden question will be shown as greyed out  colored questions.

## 🚀 Preview / testing actions

Following actions can be triggered from the test center.

* **`Trigger validation`** triggers the validation for mandatory questions or answers. 
* **`Clear validation errors`** resets and remove any validation error.
* **`Clear answers`** clears all the answers you have selected or entered in the test survey.


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# Agent Instructions: Querying This Documentation

If you need additional information that is not directly available in this page, you can query the documentation dynamically by asking a question.

Perform an HTTP GET request on the current page URL with the `ask` query parameter:

```
GET https://docs.ngsurvey.com/form-management/form-designer/preview-testing.md?ask=<question>
```

The question should be specific, self-contained, and written in natural language.
The response will contain a direct answer to the question and relevant excerpts and sources from the documentation.

Use this mechanism when the answer is not explicitly present in the current page, you need clarification or additional context, or you want to retrieve related documentation sections.