Add test coverage for getIdentity() with no identity present #821

Job	Run time
testsuite / testsuite-linux (8.4, highest, false)	1m 21s
testsuite / testsuite-linux (8.3, highest, false)	31s
cs-stan / Coding Standard & Static Analysis	30s
testsuite / testsuite-linux (8.2, lowest, false)	35s
testsuite / testsuite-linux (8.2, highest, false)	32s
testsuite / testsuite-linux (8.5, highest, false)	1m 15s
	4m 44s

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