Improve error message returned by LoadNexusMonitors

[Anders Markvardsen]

At present if LoadNexusMonitors is used to load a ISIS histogram nexus file, as e.g. AutoTestData/LOQ48127.nxs the error message is:

Error in execution of algorithm LoadNexusMonitors: All arguments to init must be positive and non-zero

If trying to load a ISIS .raw file, e.g
isis\inst$\NDXHRPD\Instrument\data\cycle_13_5\HRP58608.raw, the error message is:

Error in execution of algorithm LoadNexusMonitors: NXopen(isis/inst$/NDXHRPD/Instrument/data/cycle_13_5/HRP58608.raw, 1) failed

The algorithm currently only support loading of SNS or ISIS event raw Nexus files. Hence there could be a check to see if this is satisfied if not return a message along the lines of "blah blah file is not readable by LoadNexusMonitors"

[Federico Montesino Pouzols]

better error msgs, new check canOpenAsNeXus, re #9248

Changeset: 03df3451a8344a6d546b150a88bd51912d241234

[Federico Montesino Pouzols]

fix doxygen tag, re #9248

Changeset: e99c1d26e670aafc7aa1cf0fa628c19bef74a00c

[Federico Montesino Pouzols]

fix doxygen tag, re #9248

Changeset: dec6ba662c784405dd883270fa27225a62b945ec

[Federico M Pouzols]

LoadNexusMonitors will now give a more understantable error message when the file cannot be opened as a NeXus file, something like "Failed to recognize this file as a NeXus file, cannot continue", or "Not loading event data. Trying to load histogram data but failed to find monitors with histogram data or could not interpret the data. This file may be corrupted or it may not be supported"

Note also that the behavior of LoadNexusMonitors is being modified in #8990, with an additional option and other error condition checks. There's also some maintenance work planned for this and related algorithms: #10619.

To test:

Run commands (or use File->Open) like for example these ones:

LoadNexusMonitors('AutoTestData/LOQ48127.nxs', OutputWorkspace='foo') LoadNexusMonitors('any_random_file_that_is_definitely_not_nexus', OutputWorkspace='bar') LoadNexusMonitors('HRP58608.raw', OutputWorkspace='baz')

Check that you get understandable error messages. For files that are fine there should be no change in behavior. Tests should pass.

[Dan Nixon]

Merge remote-tracking branch 'origin/feature/9248_better_error_msgs_LoadNexusMonitors'

Full changeset: ​95a62676ff04598d039a3b6789ed950ecd3e6b8f

[Stuart Campbell]

This ticket has been transferred to github issue ​10091