MockShinySession: Mock Shiny Session
In shiny: Web Application Framework for R

MockShinySession

R Documentation

Mock Shiny Session

Description

An R6 class suitable for testing purposes. Simulates, to the extent possible, the behavior of the ShinySession class. The session parameter provided to Shiny server functions and modules is an instance of a ShinySession in normal operation.

Most kinds of module and server testing do not require this class be instantiated manually. See instead testServer().

In order to support advanced usage, instances of MockShinySession are unlocked so that public methods and fields of instances may be modified. For example, in order to test authentication workflows, the user or groups fields may be overridden. Modified instances of MockShinySession may then be passed explicitly as the session argument of testServer().

Public fields

env: The environment associated with the session.
returned: The value returned by the module under test.
singletons: Hardcoded as empty. Needed for rendering HTML (i.e. renderUI).
clientData: Mock client data that always returns a size for plots.
output: The shinyoutputs associated with the session.
input: The reactive inputs associated with the session.
userData: An environment initialized as empty.
progressStack: A stack of progress objects.
token: On a real ShinySession, used to identify this instance in URLs.
cache: The session cache object.
appcache: The app cache object.
restoreContext: Part of bookmarking support in a real ShinySession but always NULL for a MockShinySession.
groups: Character vector of groups associated with an authenticated user. Always NULL for a MockShinySesion.
user: The username of an authenticated user. Always NULL for a MockShinySession.
options: A list containing session-level shinyOptions.

Active bindings

files: For internal use only.
downloads: For internal use only.
closed: Deprecated in ShinySession and signals an error.
session: Deprecated in ShinySession and signals an error.
request: An empty environment where the request should be. The request isn't meaningfully mocked currently.

Methods

Public methods

MockShinySession$new()
MockShinySession$onFlush()
MockShinySession$onFlushed()
MockShinySession$onEnded()
MockShinySession$isEnded()
MockShinySession$isClosed()
MockShinySession$close()
MockShinySession$cycleStartAction()
MockShinySession$fileUrl()
MockShinySession$setInputs()
MockShinySession$.scheduleTask()
MockShinySession$elapse()
MockShinySession$.now()
MockShinySession$defineOutput()
MockShinySession$getOutput()
MockShinySession$ns()
MockShinySession$flushReact()
MockShinySession$makeScope()
MockShinySession$setEnv()
MockShinySession$setReturned()
MockShinySession$getReturned()
MockShinySession$genId()
MockShinySession$rootScope()
MockShinySession$onUnhandledError()
MockShinySession$unhandledError()
MockShinySession$freezeValue()
MockShinySession$onSessionEnded()
MockShinySession$registerDownload()
MockShinySession$getCurrentOutputInfo()
MockShinySession$clone()

Method `new()`

Create a new MockShinySession.

Usage

MockShinySession$new()

Method `onFlush()`

Define a callback to be invoked before a reactive flush

Usage

MockShinySession$onFlush(fun, once = TRUE)

Arguments

fun: The function to invoke
once: If TRUE, will only run once. Otherwise, will run every time reactives are flushed.

Method `onFlushed()`

Define a callback to be invoked after a reactive flush

Usage

MockShinySession$onFlushed(fun, once = TRUE)

Arguments

fun: The function to invoke
once: If TRUE, will only run once. Otherwise, will run every time reactives are flushed.

Method `onEnded()`

Define a callback to be invoked when the session ends

Usage

MockShinySession$onEnded(sessionEndedCallback)

Arguments

sessionEndedCallback: The callback to invoke when the session has ended.

Method `isEnded()`

Returns FALSE if the session has not yet been closed

Usage

MockShinySession$isEnded()

Method `isClosed()`

Returns FALSE if the session has not yet been closed

Usage

MockShinySession$isClosed()

Method `close()`

Closes the session

Usage

MockShinySession$close()

Method `cycleStartAction()`

Unsophisticated mock implementation that merely invokes

Usage

MockShinySession$cycleStartAction(callback)

Arguments

callback: The callback to be invoked.

Method `fileUrl()`

Base64-encode the given file. Needed for image rendering.

Usage

MockShinySession$fileUrl(name, file, contentType = "application/octet-stream")

Arguments

name: Not used
file: The file to be encoded
contentType: The content type of the base64-encoded string

Method `setInputs()`

Sets reactive values associated with the session$inputs object and flushes the reactives.

Usage

MockShinySession$setInputs(...)

Arguments

...: The inputs to set. These arguments are processed with rlang::list2() and so are dynamic. Input names may not be duplicated.

Examples

\dontrun{
session$setInputs(x=1, y=2)
}

Method `.scheduleTask()`

An internal method which shouldn't be used by others. Schedules callback for execution after some number of millis milliseconds.

Usage

MockShinySession$.scheduleTask(millis, callback)

Arguments

millis: The number of milliseconds on which to schedule a callback
callback: The function to schedule.

Method `elapse()`

Simulate the passing of time by the given number of milliseconds.

Usage

MockShinySession$elapse(millis)

Arguments

millis: The number of milliseconds to advance time.

Method `.now()`

An internal method which shouldn't be used by others.

Usage

MockShinySession$.now()

Returns

Elapsed time in milliseconds.

Method `defineOutput()`

An internal method which shouldn't be used by others. Defines an output in a way that sets private$currentOutputName appropriately.

Usage

MockShinySession$defineOutput(name, func, label)

Arguments

name: The name of the output.
func: The render definition.
label: Not used.

Method `getOutput()`

An internal method which shouldn't be used by others. Forces evaluation of any reactive dependencies of the output function.

Usage

MockShinySession$getOutput(name)

Arguments

name: The name of the output.

Returns

The return value of the function responsible for rendering the output.

Method `ns()`

Returns the given id prefixed by this namespace's id.

Usage

MockShinySession$ns(id)

Arguments

id: The id to prefix with a namespace id.

Returns

The id with a namespace prefix.

Method `flushReact()`

Trigger a reactive flush right now.

Usage

MockShinySession$flushReact()

Method `makeScope()`

Create and return a namespace-specific session proxy.

Usage

MockShinySession$makeScope(namespace)

Arguments

namespace: Character vector indicating a namespace.

Returns

A new session proxy.

Method `setEnv()`

Set the environment associated with a testServer() call, but only if it has not previously been set. This ensures that only the environment of the outermost module under test is the one retained. In other words, the first assignment wins.

Usage

MockShinySession$setEnv(env)

Arguments

env: The environment to retain.

Returns

The provided env.

Method `setReturned()`

Set the value returned by the module call and proactively flush. Note that this method may be called multiple times if modules are nested. The last assignment, corresponding to an invocation of setReturned() in the outermost module, wins.

Usage

MockShinySession$setReturned(value)

Arguments

value: The value returned from the module

Returns

The provided value.

Method `getReturned()`

Get the value returned by the module call.

Usage

MockShinySession$getReturned()

Returns

The value returned by the module call

Method `genId()`

Generate a distinct character identifier for use as a proxy namespace.

Usage

MockShinySession$genId()

Returns

A character identifier unique to the current session.

Method `rootScope()`

Provides a way to access the root MockShinySession from any descendant proxy.

Usage

MockShinySession$rootScope()

Returns

The root MockShinySession.

Method `onUnhandledError()`

Add an unhandled error callback.

Usage

MockShinySession$onUnhandledError(callback)

Arguments

callback: The callback to add, which should accept an error object as its first argument.

Returns

A deregistration function.

Method `unhandledError()`

Called by observers when a reactive expression errors.

Usage

MockShinySession$unhandledError(e, close = TRUE)

Arguments

e: An error object.
close: If TRUE, the session will be closed after the error is handled, defaults to FALSE.

Method `freezeValue()`

Freeze a value until the flush cycle completes.

Usage

MockShinySession$freezeValue(x, name)

Arguments

x: A ReactiveValues object.
name: The name of a reactive value within x.

Method `onSessionEnded()`

Registers the given callback to be invoked when the session is closed (i.e. the connection to the client has been severed). The return value is a function which unregisters the callback. If multiple callbacks are registered, the order in which they are invoked is not guaranteed.

Usage

MockShinySession$onSessionEnded(sessionEndedCallback)

Arguments

sessionEndedCallback: Function to call when the session ends.

Method `registerDownload()`

Associated a downloadable file with the session.

Usage

MockShinySession$registerDownload(name, filename, contentType, content)

Arguments

name: The un-namespaced output name to associate with the downloadable file.
filename: A string or function designating the name of the file.
contentType: A string of the content type of the file. Not used by MockShinySession.
content: A function that takes a single argument file that is a file path (string) of a nonexistent temp file, and writes the content to that file path. (Reactive values and functions may be used from this function.)

Method `getCurrentOutputInfo()`

Get information about the output that is currently being executed.

Usage

MockShinySession$getCurrentOutputInfo()

Returns

A list with with the name of the output. If no output is currently being executed, this will return NULL. output, or NULL if no output is currently executing.

Method `clone()`

The objects of this class are cloneable with this method.

Usage

MockShinySession$clone(deep = FALSE)

Arguments

deep: Whether to make a deep clone.

Examples


## ------------------------------------------------
## Method `MockShinySession$setInputs`
## ------------------------------------------------

## Not run: 
session$setInputs(x=1, y=2)

## End(Not run)

shiny documentation built on July 3, 2025, 9:08 a.m.

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MockShinySession: Mock Shiny Session In shiny: Web Application Framework for R