Issue #19857 has been updated by mame (Yusuke Endoh). Thanks. In your case of `ERB.new`, the `test` function does not actually use its arguments. Consider a more realistic example: ``` def test(value = nil) template = ERB.new(File.read(path).gsub("VALUE") { value || "default" }) template.result(binding) end ``` In this case, if we ever pass a multi-line string to `test`, automatic merging of the coverage results would bring trouble. I think it is safer to take only the coverage of the first or last version of code when trying to compile with the same pathname, instead of automatically merging them. ---------------------------------------- Bug #19857: Eval coverage is reset after each `eval`. https://bugs.ruby-lang.org/issues/19857#change-104478 * Author: ioquatix (Samuel Williams) * Status: Open * Priority: Normal * Assignee: ioquatix (Samuel Williams) * Backport: 3.0: DONTNEED, 3.1: DONTNEED, 3.2: REQUIRED ---------------------------------------- It seems like `eval` based coverage is reset every time eval is invoked. ```ruby #!/usr/bin/env ruby require 'coverage' def measure(flag) c = Class.new c.class_eval(<<~RUBY, "foo.rb", 1) def foo(flag) if flag puts "foo" else puts "bar" end end RUBY return c.new.foo(flag) end Coverage.start(lines: true, eval: true) # Depending on the order of these two operations, different coverage is calculated, because the evaluation of the code is considered different, even if the content/path is the same. measure(false) measure(true) p Coverage.result ``` Further investigation is required. -- https://bugs.ruby-lang.org/