IIRC the tests have been written to use a reasonable (less than 60meg) amount of memory.
The spec unfortunately makes it possible for every function to generate GL_OUT_OF_MEMORY period and still be technically spec compliant.
In other words, according to the spec an implementation could to this
GLenum glGetErrror() { return GL_OUT_OF_MEMORY; }
void glBindBuffer(...) { /* no-op */ }
void glBindTexture(...) { /* no-op */ }
void glTexImage2D(...) { /* no-op */ }
void glDrawArrays(...) { /* no-op */ }
And be valid according to the spec :-(