Organization of tests and errors checking

Plug-ins can be specialized and designing common tests may not always be possible. Test for PDI should be located in PDI test folder whereas plug-ins should be tested individually with a common approach and locally for individual feature. The following change is proposed:

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Currently the directories are organized as:

├── plugins

│ ├── FTI

│ ├── HDF5_per_process

│ ├── test_plugin

│   └── Utilities

├── Test

│ ├── test_1 // using no plug-in

│ ├── test_2 // testing with HDF5_per_process

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What we should have is :

├── plugins : check the correctness of the import/export => correct values in normalized context

│ ├── FTI

│ │ └── test for FTI

│ ├── HDF5_per_process

│ │ └── test for HDF5_...

│ ├── test_plugin

│ └── Utilities

│ -- └── test for Utilities

├── Test

│ ├── PDI // PDI ONLY (for all API functions: init/import/export/expose/finalize...)

│ │ ├── 00_init_finalize // using no external library ie: ASCII or binary

│ │ ├── 10_export // using no external library ie: ASCII or binary

│ - - └── 20_import // using no external library ie: ASCII or binary

│ ├── Plug-ins // Common tests = compatibility | no crash reported

│ │ ├── 00_init_finalize // test init

│ │ ├── 10_export // test_export do not fail (i.e: result does not matter here)

│ -- └── 20_import // test_import do not fail (i.e: result does not matter here)