Restore 100% test coverage #1171

Job	Run time
Ruby 2.7 (Windows)	3m 37s
Rubocop	32s
Ruby 3.3	4m 29s
Legacy Ruby Builds (2.1.9)	2m 9s
Ruby 3.2	3m 57s
Ruby 2.6 (Windows)	4m 43s
Legacy Ruby Builds (2.0)	2m 9s
Ruby 3.1	3m 52s
Ruby 2.5 (Windows)	2m 54s
Legacy Ruby Builds (1.9.3)	2m 23s
Ruby 3.0	4m 10s
Ruby 2.4 (Windows)	3m 17s
Legacy Ruby Builds (1.9.2)	5m 13s
Ruby 2.7	5m 21s
Legacy Ruby Builds (1.8.7)	1m 26s
Ruby 2.3 (Windows)	3m 25s
Ruby 2.6	5m 21s
Ruby 2.5	5m 18s
Ruby 2.2 (Windows)	3m 45s
Ruby 2.4	3m 52s
Legacy Ruby Builds (REE)	2m 39s
Ruby 2.3	3m 47s
Ruby 2.2	3m 58s
Legacy Ruby Builds (JRuby 1.7)	9m 49s
Ruby ruby-head	41s
Legacy Ruby Builds (JRuby 1.7 1.8 mode)	9m 34s
Ruby jruby-9.2.13.0	2m 49s
Legacy Ruby Builds (JRuby 9.1.17.0)	9m 49s
Ruby 2.7 with diff-lcs 1.3	5m 17s
Ruby 2.7 with diff-lcs 1.4.3	5m 36s
	2h 5m 52s

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