Overrides certain parts of Vim's internal processing to be able to run tests. Only to be used for testing Vim! The override is enabled when {val} is non-zero and removed when {val} is zero. Current supported values for name are: name effect when {val} is non-zero ~ redraw disable the redrawing() function redraw_flag ignore the RedrawingDisabled flag char_avail disable the char_avail() function starting reset the "starting" variable, see below nfa_fail makes the NFA regexp engine fail to force a fallback to the old engine no_query_mouse do not query the mouse position for "dec" terminals no_wait_return set the "no_wait_return" flag. Not restored with "ALL". ui_delay time in msec to use in ui_delay(); overrules a wait time of up to 3 seconds for messages term_props reset all terminal properties when the version string is detected uptime overrules sysinfo.uptime ALL clear all overrides ({val} is not used) "starting" is to be used when a test should behave like startup was done. Since the tests are run by sourcing a script the "starting" variable is non-zero. This is usually a good thing (tests run faster), but sometimes changes behavior in a way that the test doesn't work properly. When using: call test_override('starting', 1) The value of "starting" is saved. It is restored by: call test_override('starting', 0) Can also be used as a |method|: GetOverrideVal()-> test_override('starting')