tests: Preserve data dir from failed linearizability tests

[serathius]

cc @ahrtr

[codecov-commenter]

Codecov Report

Merging #14714 (c81849c) into main (f482f7b) will decrease coverage by 0.11%.
The diff coverage is n/a.

@@            Coverage Diff             @@
##             main   #14714      +/-   ##
==========================================
- Coverage   75.56%   75.44%   -0.12%     
==========================================
  Files         457      457              
  Lines       37308    37308              
==========================================
- Hits        28191    28148      -43     
- Misses       7351     7381      +30     
- Partials     1766     1779      +13     

Flag	Coverage Δ
all	75.44% <ø> (-0.12%)	⬇️

Flags with carried forward coverage won't be shown. Click here to find out more.

Impacted Files	Coverage Δ
client/pkg/v3/tlsutil/tlsutil.go	83.33% <0.00%> (-8.34%)	⬇️
client/v3/leasing/util.go	91.66% <0.00%> (-6.67%)	⬇️
server/lease/lease.go	94.87% <0.00%> (-5.13%)	⬇️
server/etcdserver/txn/util.go	75.47% <0.00%> (-3.78%)	⬇️
server/etcdserver/api/v3rpc/util.go	70.96% <0.00%> (-3.23%)	⬇️
client/v3/leasing/txn.go	88.09% <0.00%> (-3.18%)	⬇️
server/etcdserver/api/v3rpc/interceptor.go	73.43% <0.00%> (-3.13%)	⬇️
client/v3/concurrency/election.go	79.68% <0.00%> (-2.35%)	⬇️
server/etcdserver/api/v3rpc/auth.go	79.34% <0.00%> (-2.18%)	⬇️
api/etcdserverpb/raft_internal_stringer.go	81.72% <0.00%> (-2.16%)	⬇️
... and 14 more

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[ahrtr]

t.Error(err) means that the test will continue to execute .

Suggested change

	t.Error(err)
	t.Fatal(err)

[serathius]

Will still want to report model not linearizable even if writing report will not work.

[ahrtr]

Please consider to use github.com/stretchr/testify to simplify the checking on test results.

[serathius]

Please consider to use github.com/stretchr/testify to simplify the checking on test results.

Sure, maybe as a followup PR. I would want to first understand how looks testify addoption throughout other tests.

[ahrtr]

LGTM