Outputs ANSI CSI SGR formatted text to screen so that you may visually inspect what color capabilities your terminal supports.
term_cap_test()character the test vector, invisibly
The three tested terminal capabilities are:
"bright" for bright colors with SGR codes in 90-97 and 100-107
"256" for colors defined by "38;5;x" and "48;5;x" where x is in 0-255
"truecolor" for colors defined by "38;2;x;y;z" and "48;x;y;x" where x, y, and z are in 0-255
Each of the color capabilities your terminal supports should be displayed with a blue background and a red foreground. For reference the corresponding CSI SGR sequences are displayed as well.
You should compare the screen output from this function to
getOption('fansi.term.cap', dflt_term_cap) to ensure that they are self
consistent.
By default fansi assumes terminals support bright and 256 color
modes, and also tests for truecolor support via the $COLORTERM system
variable.
Functions with the term.cap parameter like substr_ctl will warn if they
encounter 256 or true color SGR sequences and term.cap indicates they are
unsupported as such a terminal may misinterpret those sequences. Bright
codes and OSC hyperlinks in terminals that do not support them will likely be
silently ignored, so fansi functions do not warn about those.
dflt_term_cap, has_ctl.