The resulting zip archive can be examined for correctness as follows.
Firstly, every Full file in the source archive should have a corresponding file in the Delta archive produced. So in the example given above (and using unix command line tools) I can get a list of the expected files (although the name will change from Full to Delta in the output):
peterw@PGW-IHTSDO-3:~/code/delta-generator-tool/target$ unzip -jl ~/Backup/xSnomedCT_InternationalRF2_BETA_20210731T120000Z.zip "*Full*txt"
Archive: /home/peterw/Backup/xSnomedCT_InternationalRF2_BETA_20210731T120000Z.zip
Length Date Time Name
--------- ---------- ----- ----
38629978 2021-05-26 09:30 xSnomedCT_InternationalRF2_BETA_20210731T120000Z/Full/Terminology/xsct2_Concept_Full_INT_20210731.txt
355767418 2021-05-26 09:30 xSnomedCT_InternationalRF2_BETA_20210731T120000Z/Full/Terminology/xsct2_Description_Full-en_INT_20210731.txt
230365824 2021-05-26 09:30 xSnomedCT_InternationalRF2_BETA_20210731T120000Z/Full/Terminology/xsct2_StatedRelationship_Full_INT_20210731.txt
668172523 2021-05-26 09:30 xSnomedCT_InternationalRF2_BETA_20210731T120000Z/Full/Terminology/xsct2_Relationship_Full_INT_20210731.txt
3194948 2021-05-26 09:31 xSnomedCT_InternationalRF2_BETA_20210731T120000Z/Full/Terminology/xsct2_RelationshipConcreteValues_Full_INT_20210731.txt
92 2021-05-26 09:31 xSnomedCT_InternationalRF2_BETA_20210731T120000Z/Full/Terminology/xsct2_Identifier_Full_INT_20210731.txt
3317229 2021-05-26 09:31 xSnomedCT_InternationalRF2_BETA_20210731T120000Z/Full/Terminology/xsct2_TextDefinition_Full-en_INT_20210731.txt
107450051 2021-05-26 09:31 xSnomedCT_InternationalRF2_BETA_20210731T120000Z/Full/Terminology/xsct2_sRefset_OWLExpressionFull_INT_20210731.txt
22358167 2021-05-26 09:31 xSnomedCT_InternationalRF2_BETA_20210731T120000Z/Full/Refset/Content/xder2_cRefset_AssociationFull_INT_20210731.txt
93730211 2021-05-26 09:31 xSnomedCT_InternationalRF2_BETA_20210731T120000Z/Full/Refset/Content/xder2_cRefset_AttributeValueFull_INT_20210731.txt
1822844 2021-05-26 09:31 xSnomedCT_InternationalRF2_BETA_20210731T120000Z/Full/Refset/Content/xder2_Refset_SimpleFull_INT_20210731.txt
52819888 2021-05-26 09:31 xSnomedCT_InternationalRF2_BETA_20210731T120000Z/Full/Refset/Map/xder2_sRefset_SimpleMapFull_INT_20210731.txt
44836866 2021-05-26 09:31 xSnomedCT_InternationalRF2_BETA_20210731T120000Z/Full/Refset/Map/xder2_iisssccRefset_ExtendedMapFull_INT_20210731.txt
410312910 2021-05-26 09:31 xSnomedCT_InternationalRF2_BETA_20210731T120000Z/Full/Refset/Language/xder2_cRefset_LanguageFull-en_INT_20210731.txt
23658 2021-05-26 09:31 xSnomedCT_InternationalRF2_BETA_20210731T120000Z/Full/Refset/Metadata/xder2_cciRefset_RefsetDescriptorFull_INT_20210731.txt
9329 2021-05-26 09:31 xSnomedCT_InternationalRF2_BETA_20210731T120000Z/Full/Refset/Metadata/xder2_ssRefset_ModuleDependencyFull_INT_20210731.txt
619 2021-05-26 09:31 xSnomedCT_InternationalRF2_BETA_20210731T120000Z/Full/Refset/Metadata/xder2_ciRefset_DescriptionTypeFull_INT_20210731.txt
390320 2021-05-26 09:31 xSnomedCT_InternationalRF2_BETA_20210731T120000Z/Full/Refset/Metadata/xder2_sssssssRefset_MRCMDomainFull_INT_20210731.txt
28379 2021-05-26 09:31 xSnomedCT_InternationalRF2_BETA_20210731T120000Z/Full/Refset/Metadata/xder2_cissccRefset_MRCMAttributeDomainFull_INT_20210731.txt
104481 2021-05-26 09:31 xSnomedCT_InternationalRF2_BETA_20210731T120000Z/Full/Refset/Metadata/xder2_ssccRefset_MRCMAttributeRangeFull_INT_20210731.txt
403 2021-05-26 09:31 xSnomedCT_InternationalRF2_BETA_20210731T120000Z/Full/Refset/Metadata/xder2_cRefset_MRCMModuleScopeFull_INT_20210731.txt
--------- -------
2033336138 21 files
So if I then run the same command on the resulting archive, I expect to see an equivalent set of files:
peterw@PGW-IHTSDO-3:~/code/delta-generator-tool/target$ unzip -jl xSnomedCT_InternationalRF2_BETA_20210731T120000Z.zip "*txt"
Archive: xSnomedCT_InternationalRF2_BETA_20210731T120000Z.zip
Length Date Time Name
--------- ---------- ----- ----
2470377 2021-10-28 13:30 xSnomedCT_InternationalRF2_BETA_20210731T120000Z/Delta/Refset/Content/xder2_cRefset_AssociationDelta_INT_20210731.txt
8402337 2021-10-28 13:30 xSnomedCT_InternationalRF2_BETA_20210731T120000Z/Delta/Refset/Content/xder2_cRefset_AttributeValueDelta_INT_20210731.txt
29320 2021-10-28 13:30 xSnomedCT_InternationalRF2_BETA_20210731T120000Z/Delta/Refset/Content/xder2_Refset_SimpleDelta_INT_20210731.txt
8284764 2021-10-28 13:30 xSnomedCT_InternationalRF2_BETA_20210731T120000Z/Delta/Refset/Language/xder2_cRefset_LanguageDelta-en_INT_20210731.txt
1706205 2021-10-28 13:30 xSnomedCT_InternationalRF2_BETA_20210731T120000Z/Delta/Refset/Map/xder2_iisssccRefset_ExtendedMapDelta_INT_20210731.txt
850176 2021-10-28 13:30 xSnomedCT_InternationalRF2_BETA_20210731T120000Z/Delta/Refset/Map/xder2_sRefset_SimpleMapDelta_INT_20210731.txt
1209 2021-10-28 13:30 xSnomedCT_InternationalRF2_BETA_20210731T120000Z/Delta/Refset/Metadata/xder2_cciRefset_RefsetDescriptorDelta_INT_20210731.txt
101 2021-10-28 13:30 xSnomedCT_InternationalRF2_BETA_20210731T120000Z/Delta/Refset/Metadata/xder2_ciRefset_DescriptionTypeDelta_INT_20210731.txt
4225 2021-10-28 13:30 xSnomedCT_InternationalRF2_BETA_20210731T120000Z/Delta/Refset/Metadata/xder2_cissccRefset_MRCMAttributeDomainDelta_INT_20210731.txt
82 2021-10-28 13:30 xSnomedCT_InternationalRF2_BETA_20210731T120000Z/Delta/Refset/Metadata/xder2_cRefset_MRCMModuleScopeDelta_INT_20210731.txt
11178 2021-10-28 13:30 xSnomedCT_InternationalRF2_BETA_20210731T120000Z/Delta/Refset/Metadata/xder2_ssccRefset_MRCMAttributeRangeDelta_INT_20210731.txt
813 2021-10-28 13:30 xSnomedCT_InternationalRF2_BETA_20210731T120000Z/Delta/Refset/Metadata/xder2_ssRefset_ModuleDependencyDelta_INT_20210731.txt
58008 2021-10-28 13:30 xSnomedCT_InternationalRF2_BETA_20210731T120000Z/Delta/Refset/Metadata/xder2_sssssssRefset_MRCMDomainDelta_INT_20210731.txt
1391422 2021-10-28 13:30 xSnomedCT_InternationalRF2_BETA_20210731T120000Z/Delta/Terminology/xsct2_Concept_Delta_INT_20210731.txt
6557571 2021-10-28 13:30 xSnomedCT_InternationalRF2_BETA_20210731T120000Z/Delta/Terminology/xsct2_Description_Delta-en_INT_20210731.txt
92 2021-10-28 13:30 xSnomedCT_InternationalRF2_BETA_20210731T120000Z/Delta/Terminology/xsct2_Identifier_Delta_INT_20210731.txt
3194948 2021-10-28 13:30 xSnomedCT_InternationalRF2_BETA_20210731T120000Z/Delta/Terminology/xsct2_RelationshipConcreteValues_Delta_INT_20210731.txt
24359872 2021-10-28 13:30 xSnomedCT_InternationalRF2_BETA_20210731T120000Z/Delta/Terminology/xsct2_Relationship_Delta_INT_20210731.txt
20108465 2021-10-28 13:30 xSnomedCT_InternationalRF2_BETA_20210731T120000Z/Delta/Terminology/xsct2_sRefset_OWLExpressionDelta_INT_20210731.txt
114 2021-10-28 13:30 xSnomedCT_InternationalRF2_BETA_20210731T120000Z/Delta/Terminology/xsct2_StatedRelationship_Delta_INT_20210731.txt
359929 2021-10-28 13:30 xSnomedCT_InternationalRF2_BETA_20210731T120000Z/Delta/Terminology/xsct2_TextDefinition_Delta-en_INT_20210731.txt
--------- -------
77791208 21 files
peterw@PGW-IHTSDO-3:~/code/delta-generator-tool/target$
Secondly, in terms on the individual files, we can examine the number of rows for each particular effective time, and then for the effective times that we expect to have received in the output, there should be the same number of rows for each effectiveTime. I'll check the Concept file as an example (using the unix 'cut' command to pull out just the 2nd column, the effectiveTime, in the file and then sorting and asking for a unique count of each value present):
peterw@PGW-IHTSDO-3:~/code/delta-generator-tool/target$ unzip -j ~/Backup/xSnomedCT_InternationalRF2_BETA_20210731T120000Z.zip "*Concep*Full*"
Archive: /home/peterw/Backup/xSnomedCT_InternationalRF2_BETA_20210731T120000Z.zip
inflating: xsct2_Concept_Full_INT_20210731.txt
peterw@PGW-IHTSDO-3:~/code/delta-generator-tool/target$ cat xsct2_Concept_Full_INT_20210731.txt | cut -f 2 | sort | uniq -c
<ignoring earlier releases...>
6628 20180131
21544 20180731
16311 20190131
10029 20190731
6036 20200131
7564 20200731
8972 20210131
13966 20210731
1 effectiveTime
Now, when the tool was run, I asked for rows after 20200731, so I expect to see 8972 + 13966 + 1 x header rows in my delta file produced:
peterw@PGW-IHTSDO-3:~/code/delta-generator-tool/target$ unzip -j xSnomedCT_InternationalRF2_BETA_20210731T120000Z.zip "*Concept*"
Archive: xSnomedCT_InternationalRF2_BETA_20210731T120000Z.zip
inflating: xsct2_Concept_Delta_INT_20210731.txt
peterw@PGW-IHTSDO-3:~/code/delta-generator-tool/target$ cat xsct2_Concept_Delta_INT_20210731.txt | cut -f 2 | sort | uniq -c
8972 20210131
13966 20210731
1 effectiveTime
peterw@PGW-IHTSDO-3:~/code/delta-generator-tool/target$
I could continue to check all the files present, and then individual rows produced for increased confidence.