add `app$waitForValue`

[schloerke]

Fixes #301

• Document Usage
• Document R6 docs
• Document website, in Testing in Depth
• Document website, in FAQ
• NEWS item

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Prior

app <- ShinyDriver$new("../../", seed = 100, shinyOptions = list(display.mode = "normal"))
app$snapshotInit("mytest")

Sys.sleep(5)
app$snapshot()

app$setInputs(state = "California")
Sys.sleep(1)
app$snapshot()

New

app <- ShinyDriver$new("../../", seed = 100, shinyOptions = list(display.mode = "normal"))
shinyOptions = list(display.mode = "normal"))
app$snapshotInit("mytest")

initValue <- app$waitForValue("state")
app$snapshot()

app$setInputs(state = "California")
app$waitForValue("state", initValue)

app$snapshot()

System time for both waitForValue calls take < 1s on my machine.

[schloerke]

I don't know if this would actually work....

app <- ShinyDriver$new("../../", seed = 100, shinyOptions = list(display.mode = "normal"))
shinyOptions = list(display.mode = "normal"))
app$snapshotInit("mytest")

initValue <- app$waitForValue("state")
app$snapshot()

app$setInputs(state = "California")
app$waitForValue("state", initValue)

app$snapshot()

I have a feeling that the last snapshot will be called before the ggplot2 value is set.

I think it would almost need a

app$setInputs(state = "California")
app$waitForValue("state", initValue)
app$waitForValue("plot", priorPlotValue, iotype = "output")

app$snapshot()

@wch What about adding another function that says app$waitForUpdatedValue which will capture the existing value and keep checking until the retrieved value does not match the initial retrieved value? Should we go down the app$waitForValues / app$waitForUpdatedValues route as well?

[wch]

Thoughts:

• Change invalidValues to ignore
• Always use list() in examples for ignore
• Document this usage pattern:

priorPlotValue <- app$getValue("plot")
app$setInputs(state = "California")
app$waitForValue("state", ignore = list(initValue))
app$waitForValue("plot", ignore = list(priorPlotValue), iotype = "output")
app$snapshot()