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Test an app without a terminal

Source: R/testing.R
test_app.Rd

Starts the app with a headless driver and returns a Pilot that simulates the user. Every action runs one tick of the real event loop (input -> events -> timers -> repaint), and the output goes through the real renderer into a virtual terminal, so tests see exactly what a user would see.

Usage

test_app(app, width = 80L, height = 24L, color_mode = "truecolor")

Arguments

app

An App or a widget.

width, height

Virtual terminal size.

color_mode

Colour support of the virtual terminal: "truecolor" (default), "256", "16" or "none" (monochrome, as with NO_COLOR).

Value

A Pilot object.

Details

Pilot methods:

  • press(...): press keys, e.g. press("tab", "enter", "ctrl+c");

  • type(text): type characters;

  • resize(width, height): resize the terminal;

  • advance(seconds): let simulated time pass (fires timers);

  • click(target, y = NULL, button = "left"): click a widget (a selector or widget; the centre of its visible part is used) or a position click(x, y);

  • hover(target), scroll(target, direction = "down", times = 1): move the pointer, turn the mouse wheel;

  • mouse(action, x, y, button, direction): send a raw mouse event;

  • drag(from, to, button = "left", steps = 3): press, move and release between two positions (selectors, widgets or c(x, y));

  • paste(text): deliver a bracketed paste; system_clipboard(): text of the last OSC 52 write;

  • focus(target), find(selector): focus a widget, find one;

  • wait_for(condition, timeout = 5): step the event loop (simulated time, real time while workers run) until condition(app) is TRUE;

  • run_worker(fn, ..., wait = TRUE): start a worker and wait for it;

  • wait_for_workers(timeout): wait for background workers to finish;

  • screen_text(): the visible screen as a character vector;

  • snapshot(): print the screen (for testthat::expect_snapshot());

  • query_one(selector), query(selector): find widgets;

  • stop(): exit the app and restore the (virtual) terminal.

Fields: app, driver, exited and value (the value passed to app$exit()).

Examples

pilot <- test_app(app(input(id = "name")), width = 30, height = 5)
pilot$type("Ada")
pilot$query_one("#name")$value
#> [1] "Ada"
pilot$stop()