The AppTest class
A simulated Streamlit app to check the correctness of displayed elements and outputs.
An instance of AppTest simulates a running Streamlit app. This class provides methods to set up, manipulate, and inspect the app contents via API instead of a browser UI. It can be used to write automated tests of an app in various scenarios. These can then be run using a tool like pytest.
AppTest can be initialized by one of three class methods:
- st.testing.v1.AppTest.from_file (recommended)
- st.testing.v1.AppTest.from_string
- st.testing.v1.AppTest.from_function
Once initialized, Session State and widget values can be updated and the script can be run. Unlike an actual live-running Streamlit app, you need to call AppTest.run() explicitly to re-run the app after changing a widget value. Switching pages also requires an explicit, follow-up call to AppTest.run().
AppTest enables developers to build tests on their app as-is, in the familiar python test format, without major refactoring or abstracting out logic to be tested separately from the UI. Tests can run quickly with very low overhead. A typical pattern is to build a suite of tests for an app that ensure consistent functionality as the app evolves, and run the tests locally and/or in a CI environment like Github Actions.
Note
AppTest only supports testing a single page of an app per instance. For multipage apps, each page will need to be tested separately. AppTest is not yet compatible with multipage apps using st.navigation and st.Page.
| Class description[source] | |
|---|---|
st.testing.v1.AppTest(script_path, *, default_timeout, args=None, kwargs=None) | |
| Methods | |
get(element_type) | Get elements or widgets of the specified type. |
run(*, timeout=None) | Run the script from the current state. |
switch_page(page_path) | Switch to another page of the app. |
| Attributes | |
secrets (dict[str, Any]) | Dictionary of secrets to be used the simulated app. Use dict-like syntax to set secret values for the simulated app. |
session_state (SafeSessionState) | Session State for the simulated app. SafeSessionState object supports read and write operations as usual for Streamlit apps. |
query_params (dict[str, Any]) | Dictionary of query parameters to be used by the simluated app. Use dict-like syntax to set query_params values for the simulated app. |
Sequence of all st.button and st.form_submit_button widgets. | |
Sequence of all st.feedback widgets. | |
Sequence of all st.caption elements. | |
Sequence of all st.chat_input widgets. | |
Sequence of all st.chat_message elements. | |
Sequence of all st.checkbox widgets. | |
Sequence of all st.code elements. | |
Sequence of all st.color_picker widgets. | |
Sequence of all columns within st.columns elements. | |
Sequence of all st.dataframe elements. | |
Sequence of all st.date_input widgets. | |
Sequence of all st.divider elements. | |
Sequence of all st.error elements. | |
Sequence of all st.exception elements. | |
Sequence of all st.expander elements. | |
Sequence of all st.header elements. | |
Sequence of all st.info elements. | |
Sequence of all st.json elements. | |
Sequence of all st.latex elements. | |
Sequence of elements within the main body of the app. | |
Sequence of all st.markdown elements. | |
Sequence of all st.metric elements. | |
Sequence of all st.multiselect widgets. | |
Sequence of all st.number_input widgets. | |
Sequence of all st.radio widgets. | |
Sequence of all st.select_slider widgets. | |
Sequence of all st.selectbox widgets. | |
Sequence of all elements within st.sidebar. | |
Sequence of all st.slider widgets. | |
Sequence of all st.status elements. | |
Sequence of all st.subheader elements. | |
Sequence of all st.success elements. | |
Sequence of all st.table elements. | |
Sequence of all tabs within st.tabs elements. | |
Sequence of all st.text elements. | |
Sequence of all st.text_area widgets. | |
Sequence of all st.text_input widgets. | |
Sequence of all st.time_input widgets. | |
Sequence of all st.title elements. | |
Sequence of all st.toast elements. | |
Sequence of all st.toggle widgets. | |
Sequence of all st.warning elements. | |
Initialize a simulated app using AppTest
Create an instance of AppTest to simulate an app page defined within a file.
This option is most convenient for CI workflows and testing of published apps. The script must be executable on its own and so must contain all necessary imports.
| Function signature[source] | |
|---|---|
AppTest.from_file(cls, script_path, *, default_timeout=3) | |
| Parameters | |
script_path (str | Path) | Path to a script file. The path should be absolute or relative to the file calling .from_file. |
default_timeout (float) | Default time in seconds before a script run is timed out. Can be overridden for individual .run() calls. |
| Returns | |
(AppTest) | A simulated Streamlit app for testing. The simulated app can be executed via .run(). |
Create an instance of AppTest to simulate an app page defined within a string.
This is useful for testing short scripts that fit comfortably as an inline string in the test itself, without having to create a separate file for it. The script must be executable on its own and so must contain all necessary imports.
| Function signature[source] | |
|---|---|
AppTest.from_string(cls, script, *, default_timeout=3) | |
| Parameters | |
script (str) | The string contents of the script to be run. |
default_timeout (float) | Default time in seconds before a script run is timed out. Can be overridden for individual .run() calls. |
| Returns | |
(AppTest) | A simulated Streamlit app for testing. The simulated app can be executed via .run(). |
Create an instance of AppTest to simulate an app page defined within a function.
This is similar to AppTest.from_string(), but more convenient to write with IDE assistance. The script must be executable on its own and so must contain all necessary imports.
| Function signature[source] | |
|---|---|
AppTest.from_function(cls, script, *, default_timeout=3, args=None, kwargs=None) | |
| Parameters | |
script (Callable) | A function whose body will be used as a script. Must be runnable in isolation, so it must include any necessary imports. |
default_timeout (float) | Default time in seconds before a script run is timed out. Can be overridden for individual .run() calls. |
args (tuple) | An optional tuple of args to pass to the script function. |
kwargs (dict) | An optional dict of kwargs to pass to the script function. |
| Returns | |
(AppTest) | A simulated Streamlit app for testing. The simulated app can be executed via .run(). |
Run an AppTest script
Run the script from the current state.
This is equivalent to manually rerunning the app or the rerun that occurs upon user interaction. AppTest.run() must be manually called after updating a widget value or switching pages as script reruns do not occur automatically as they do for live-running Streamlit apps.
| Function signature[source] | |
|---|---|
AppTest.run(*, timeout=None) | |
| Parameters | |
timeout (float or None) | The maximum number of seconds to run the script. If timeout is None (default), Streamlit uses the default timeout set for the instance of AppTest. |
| Returns | |
(AppTest) | self |
Switch to another page of the app.
This method does not automatically rerun the app. Use a follow-up call to AppTest.run() to obtain the elements on the selected page.
| Function signature[source] | |
|---|---|
AppTest.switch_page(page_path) | |
| Parameters | |
page_path (str) | Path of the page to switch to. The path must be relative to the main script's location (e.g. "pages/my_page.py"). |
| Returns | |
(AppTest) | self |
Get AppTest script elements
The main value of AppTest is providing an API to programmatically inspect and interact with the elements and widgets produced by a running Streamlit app. Using the AppTest.<element type> properties or AppTest.get() method returns a collection of all the elements or widgets of the specified type that would have been displayed by running the app.
Note that you can also retrieve elements within a specific container in the same way - first retrieve the container, then retrieve the elements just in that container.
Get elements or widgets of the specified type.
This method returns the collection of all elements or widgets of the specified type on the current page. Retrieve a specific element by using its index (order on page) or key lookup.
| Function signature[source] | |
|---|---|
AppTest.get(element_type) | |
| Parameters | |
element_type (str) | An element attribute of AppTest. For example, "button", "caption", or "chat_input". |
| Returns | |
(Sequence of Elements) | Sequence of elements of the given type. Individual elements can be accessed from a Sequence by index (order on the page). When getting and element_type that is a widget, individual widgets can be accessed by key. For example, at.get("text")[0] for the first st.text element or at.get("slider")(key="my_key") for the st.slider widget with a given key. |
| Function signature[source] | |
|---|---|
AppTest.button | |
| Returns | |
(WidgetList of Button) | Sequence of all st.button and st.form_submit_button widgets. Individual widgets can be accessed from a WidgetList by index (order on the page) or key. For example, at.button[0] for the first widget or at.button(key="my_key") for a widget with a given key. |
| Function signature[source] | |
|---|---|
AppTest.caption | |
| Returns | |
(ElementList of Caption) | Sequence of all st.caption elements. Individual elements can be accessed from an ElementList by index (order on the page). For example, at.caption[0] for the first element. Caption is an extension of the Element class. |
| Function signature[source] | |
|---|---|
AppTest.chat_input | |
| Returns | |
(WidgetList of ChatInput) | Sequence of all st.chat_input widgets. Individual widgets can be accessed from a WidgetList by index (order on the page) or key. For example, at.chat_input[0] for the first widget or at.chat_input(key="my_key") for a widget with a given key. |
| Function signature[source] | |
|---|---|
AppTest.chat_message | |
| Returns | |
(Sequence of ChatMessage) | Sequence of all st.chat_message elements. Individual elements can be accessed from an ElementList by index (order on the page). For example, at.chat_message[0] for the first element. ChatMessage is an extension of the Block class. |
| Function signature[source] | |
|---|---|
AppTest.checkbox | |
| Returns | |
(WidgetList of Checkbox) | Sequence of all st.checkbox widgets. Individual widgets can be accessed from a WidgetList by index (order on the page) or key. For example, at.checkbox[0] for the first widget or at.checkbox(key="my_key") for a widget with a given key. |
| Function signature[source] | |
|---|---|
AppTest.code | |
| Returns | |
(ElementList of Code) | Sequence of all st.code elements. Individual elements can be accessed from an ElementList by index (order on the page). For example, at.code[0] for the first element. Code is an extension of the Element class. |
| Function signature[source] | |
|---|---|
AppTest.color_picker | |
| Returns | |
(WidgetList of ColorPicker) | Sequence of all st.color_picker widgets. Individual widgets can be accessed from a WidgetList by index (order on the page) or key. For example, at.color_picker[0] for the first widget or at.color_picker(key="my_key") for a widget with a given key. |
Sequence of all columns within st.columns elements.
Each column within a single st.columns will be returned as a separate Column in the Sequence.
| Function signature[source] | |
|---|---|
AppTest.columns | |
| Returns | |
(Sequence of Column) | Sequence of all columns within st.columns elements. Individual columns can be accessed from an ElementList by index (order on the page). For example, at.columns[0] for the first column. Column is an extension of the Block class. |
| Function signature[source] | |
|---|---|
AppTest.dataframe | |
| Returns | |
(ElementList of Dataframe) | Sequence of all st.dataframe elements. Individual elements can be accessed from an ElementList by index (order on the page). For example, at.dataframe[0] for the first element. Dataframe is an extension of the Element class. |
| Function signature[source] | |
|---|---|
AppTest.date_input | |
| Returns | |
(WidgetList of DateInput) | Sequence of all st.date_input widgets. Individual widgets can be accessed from a WidgetList by index (order on the page) or key. For example, at.date_input[0] for the first widget or at.date_input(key="my_key") for a widget with a given key. |
| Function signature[source] | |
|---|---|
AppTest.divider | |
| Returns | |
(ElementList of Divider) | Sequence of all st.divider elements. Individual elements can be accessed from an ElementList by index (order on the page). For example, at.divider[0] for the first element. Divider is an extension of the Element class. |
| Function signature[source] | |
|---|---|
AppTest.error | |
| Returns | |
(ElementList of Error) | Sequence of all st.error elements. Individual elements can be accessed from an ElementList by index (order on the page). For example, at.error[0] for the first element. Error is an extension of the Element class. |
| Function signature[source] | |
|---|---|
AppTest.exception | |
| Returns | |
(ElementList of Exception) | Sequence of all st.exception elements. Individual elements can be accessed from an ElementList by index (order on the page). For example, at.exception[0] for the first element. Exception is an extension of the Element class. |
| Function signature[source] | |
|---|---|
AppTest.expander | |
| Returns | |
(Sequence of Expandable) | Sequence of all st.expander elements. Individual elements can be accessed from a Sequence by index (order on the page). For example, at.expander[0] for the first element. Expandable is an extension of the Block class. |
| Function signature[source] | |
|---|---|
AppTest.header | |
| Returns | |
(ElementList of Header) | Sequence of all st.header elements. Individual elements can be accessed from an ElementList by index (order on the page). For example, at.header[0] for the first element. Header is an extension of the Element class. |
| Function signature[source] | |
|---|---|
AppTest.info | |
| Returns | |
(ElementList of Info) | Sequence of all st.info elements. Individual elements can be accessed from an ElementList by index (order on the page). For example, at.info[0] for the first element. Info is an extension of the Element class. |
| Function signature[source] | |
|---|---|
AppTest.json | |
| Returns | |
(ElementList of Json) | Sequence of all st.json elements. Individual elements can be accessed from an ElementList by index (order on the page). For example, at.json[0] for the first element. Json is an extension of the Element class. |
| Function signature[source] | |
|---|---|
AppTest.latex | |
| Returns | |
(ElementList of Latex) | Sequence of all st.latex elements. Individual elements can be accessed from an ElementList by index (order on the page). For example, at.latex[0] for the first element. Latex is an extension of the Element class. |
| Function signature[source] | |
|---|---|
AppTest.main | |
| Returns | |
(Block) | A container of elements. Block can be queried for elements in the same manner as AppTest. For example, Block.checkbox will return all st.checkbox within the associated container. |
| Function signature[source] | |
|---|---|
AppTest.markdown | |
| Returns | |
(ElementList of Markdown) | Sequence of all st.markdown elements. Individual elements can be accessed from an ElementList by index (order on the page). For example, at.markdown[0] for the first element. Markdown is an extension of the Element class. |
| Function signature[source] | |
|---|---|
AppTest.metric | |
| Returns | |
(ElementList of Metric) | Sequence of all st.metric elements. Individual elements can be accessed from an ElementList by index (order on the page). For example, at.metric[0] for the first element. Metric is an extension of the Element class. |
| Function signature[source] | |
|---|---|
AppTest.multiselect | |
| Returns | |
(WidgetList of Multiselect) | Sequence of all st.multiselect widgets. Individual widgets can be accessed from a WidgetList by index (order on the page) or key. For example, at.multiselect[0] for the first widget or at.multiselect(key="my_key") for a widget with a given key. |
| Function signature[source] | |
|---|---|
AppTest.number_input | |
| Returns | |
(WidgetList of NumberInput) | Sequence of all st.number_input widgets. Individual widgets can be accessed from a WidgetList by index (order on the page) or key. For example, at.number_input[0] for the first widget or at.number_input(key="my_key") for a widget with a given key. |
| Function signature[source] | |
|---|---|
AppTest.radio | |
| Returns | |
(WidgetList of Radio) | Sequence of all st.radio widgets. Individual widgets can be accessed from a WidgetList by index (order on the page) or key. For example, at.radio[0] for the first widget or at.radio(key="my_key") for a widget with a given key. |
| Function signature[source] | |
|---|---|
AppTest.select_slider | |
| Returns | |
(WidgetList of SelectSlider) | Sequence of all st.select_slider widgets. Individual widgets can be accessed from a WidgetList by index (order on the page) or key. For example, at.select_slider[0] for the first widget or at.select_slider(key="my_key") for a widget with a given key. |
| Function signature[source] | |
|---|---|
AppTest.selectbox | |
| Returns | |
(WidgetList of Selectbox) | Sequence of all st.selectbox widgets. Individual widgets can be accessed from a WidgetList by index (order on the page) or key. For example, at.selectbox[0] for the first widget or at.selectbox(key="my_key") for a widget with a given key. |
| Function signature[source] | |
|---|---|
AppTest.sidebar | |
| Returns | |
(Block) | A container of elements. Block can be queried for elements in the same manner as AppTest. For example, Block.checkbox will return all st.checkbox within the associated container. |
| Function signature[source] | |
|---|---|
AppTest.slider | |
| Returns | |
(WidgetList of Slider) | Sequence of all st.slider widgets. Individual widgets can be accessed from a WidgetList by index (order on the page) or key. For example, at.slider[0] for the first widget or at.slider(key="my_key") for a widget with a given key. |
| Function signature[source] | |
|---|---|
AppTest.subheader | |
| Returns | |
(ElementList of Subheader) | Sequence of all st.subheader elements. Individual elements can be accessed from an ElementList by index (order on the page). For example, at.subheader[0] for the first element. Subheader is an extension of the Element class. |
| Function signature[source] | |
|---|---|
AppTest.success | |
| Returns | |
(ElementList of Success) | Sequence of all st.success elements. Individual elements can be accessed from an ElementList by index (order on the page). For example, at.success[0] for the first element. Success is an extension of the Element class. |
| Function signature[source] | |
|---|---|
AppTest.status | |
| Returns | |
(Sequence of Status) | Sequence of all st.status elements. Individual elements can be accessed from a Sequence by index (order on the page). For example, at.status[0] for the first element. Status is an extension of the Block class. |
| Function signature[source] | |
|---|---|
AppTest.table | |
| Returns | |
(ElementList of Table) | Sequence of all st.table elements. Individual elements can be accessed from an ElementList by index (order on the page). For example, at.table[0] for the first element. Table is an extension of the Element class. |
Sequence of all tabs within st.tabs elements.
Each tab within a single st.tabs will be returned as a separate Tab in the Sequence. Additionally, the tab labels are forwarded to each Tab element as a property. For example, st.tabs("A","B") will yield two Tab objects, with Tab.label returning "A" and "B", respectively.
| Function signature[source] | |
|---|---|
AppTest.tabs | |
| Returns | |
(Sequence of Tab) | Sequence of all tabs within st.tabs elements. Individual tabs can be accessed from an ElementList by index (order on the page). For example, at.tabs[0] for the first tab. Tab is an extension of the Block class. |
| Function signature[source] | |
|---|---|
AppTest.text | |
| Returns | |
(ElementList of Text) | Sequence of all st.text elements. Individual elements can be accessed from an ElementList by index (order on the page). For example, at.text[0] for the first element. Text is an extension of the Element class. |
| Function signature[source] | |
|---|---|
AppTest.text_area | |
| Returns | |
(WidgetList of TextArea) | Sequence of all st.text_area widgets. Individual widgets can be accessed from a WidgetList by index (order on the page) or key. For example, at.text_area[0] for the first widget or at.text_area(key="my_key") for a widget with a given key. |
| Function signature[source] | |
|---|---|
AppTest.text_input | |
| Returns | |
(WidgetList of TextInput) | Sequence of all st.text_input widgets. Individual widgets can be accessed from a WidgetList by index (order on the page) or key. For example, at.text_input[0] for the first widget or at.text_input(key="my_key") for a widget with a given key. |
| Function signature[source] | |
|---|---|
AppTest.time_input | |
| Returns | |
(WidgetList of TimeInput) | Sequence of all st.time_input widgets. Individual widgets can be accessed from a WidgetList by index (order on the page) or key. For example, at.time_input[0] for the first widget or at.time_input(key="my_key") for a widget with a given key. |
| Function signature[source] | |
|---|---|
AppTest.title | |
| Returns | |
(ElementList of Title) | Sequence of all st.title elements. Individual elements can be accessed from an ElementList by index (order on the page). For example, at.title[0] for the first element. Title is an extension of the Element class. |
| Function signature[source] | |
|---|---|
AppTest.toast | |
| Returns | |
(ElementList of Toast) | Sequence of all st.toast elements. Individual elements can be accessed from an ElementList by index (order on the page). For example, at.toast[0] for the first element. Toast is an extension of the Element class. |
| Function signature[source] | |
|---|---|
AppTest.toggle | |
| Returns | |
(WidgetList of Toggle) | Sequence of all st.toggle widgets. Individual widgets can be accessed from a WidgetList by index (order on the page) or key. For example, at.toggle[0] for the first widget or at.toggle(key="my_key") for a widget with a given key. |
| Function signature[source] | |
|---|---|
AppTest.warning | |
| Returns | |
(ElementList of Warning) | Sequence of all st.warning elements. Individual elements can be accessed from an ElementList by index (order on the page). For example, at.warning[0] for the first element. Warning is an extension of the Element class. |
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