| Subject: | Tests assume the pbm terminal exists, but newer gnuplot versions (>=4.6.0) omit it by default |
Ideally the tests switch to another default terminal type, or dynamically adjust to whatever terminals are available (within reason).
For anyone else running into this issue, try recompiling your gnuplot using the --with-bitmap-terminals option to configure. Alternatively, just skip the tests and don't use the pbm terminal in your code!