devtools.selftest () launches the server as a subprocess, drives a short session through it in each of the two protocol eras, and prints what it found. A server that answers only one era works with only some hosts, so both are exercised. The check it exists for is the one that cannot be made from inside: that every byte written to standard output was a protocol message. A stray printf, an unsuppressed statement or a line printed by ~/.octaverc corrupts the stream, and the only symptom a host can show for it is an unexplained failure to connect. Standard error is read too, for the complementary claim: the server may write its own diagnostics there, but a diagnostic the interpreter raised about the server is a defect nothing else here would see.

OK = devtools.selftest () returns true when every check passed and prints nothing, which is the form a test uses.

[OK, REPORT] = devtools.selftest () also returns the cell array of strings that would have been printed, one per check.

… = devtools.selftest (CMD) tests the shell command CMD rather than the default one. Give it the exact command from your host configuration to find out whether that configuration is sound; it must launch a server that reads standard input and writes standard output, and nothing else. The default launches the interpreter running this function against the package directory this file lives in, which works from a source tree as well as from an installed package.

See also: devtools.mcp

Source Code: devtools.selftest