LoadNexusProcessed: root-level NXentry groups

[ekapadi]

Description of work

Mantid's interpretation of the NeXus format uses multiple root-level "NX_class: NXentry" groups to store multiple workspaces in a single NeXus HDF5 file. By using additional root-level groups, such as "NX_class: NXcollection", metadata about a group of workspaces may be stored. In addition, the NeXus format itself allows other, non-NeXus information to be stored in an HDF5 file, provided it avoids collisions with the NeXus naming system. In combination, all of this led to the requirement solved by the current PR, which allows LoadNexusProcessed to function correctly in the presence of other root-level non-NXentry and non-NeXus groups.

Summary of work

This commit includes the following changes:

• When LoadNexusProcessed is determining the number of workspaces in a NeXus HDF5 file, it now counts the number of root-level "NX_class: NXentry" groups. Previously, it counted the number of root-level groups, assuming all were of "NX_class: NXentry".

EWM ref:

EWM#7148

To test:

A new unit test has been added to test these changes: LoadNexusProcessedTest::test_load_workspace_group_other_root_groups.

In order to verify these changes "by hand" it's recommended to take a look at the contents of the test-input file: build/ExternalData/Testing/Data/UnitTest/WorkspaceGroup_other_groups.nxs using the h5dump tool. In addition to including twelve workspaces (, as NX_class: NXentry "mantid_workspace_nn" groups), this file adds a root-level NX_class: NXcollection "metadata" group, and another root-level non-NeXus group. Following the form of the new unit test, verify that LoadNexusProcessed loads this file as a group workspace, and successfully ignores the other root-level groups in the file.

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Reviewer

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Code Review

• Is the code of an acceptable quality?
• Does the code conform to the coding standards?
• Are the unit tests small and test the class in isolation?
• If there is GUI work does it follow the GUI standards?
• If there are changes in the release notes then do they describe the changes appropriately?
• Do the release notes conform to the release notes guide?

Functional Tests

• Do changes function as described? Add comments below that describe the tests performed?
• Do the changes handle unexpected situations, e.g. bad input?
• Has the relevant (user and developer) documentation been added/updated?

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[sf1919]

Please can you add a milestone to this PR? If you can add labels too that would be good.

[walshmm]

Building too much longer than verifying 😅

Code Review

• Is the code of an acceptable quality?
• Does the code conform to the [coding standards](http://developer.mantidproject.org/
• Are the unit tests small and test the class in
• If there is GUI work does it follow the [GUI standards](http://developer.mantidproject.org/Standards/GUIStandards.
• If there are changes in the release notes then do they describe the changes
• Do the release notes conform to the release notes guide?

Functional

• Do changes function as described? Add comments below that describe the tests

Grep of the test file listing the 12 expected workspaces

And a sample of the newly added metadata:

all Root level groups can be see here:

where there are the two additional groups that are not workspaces.

• Do the changes handle unexpected situations, e.g. bad
• Has the relevant (user and developer) documentation been added/updated?

[walshmm]

The test written does confirm that in the presence of these other groups it will function and load the file.

[walshmm]

Approved, please find a gatekeeper!