Table 4.

Test smells included in our study, their definition, and the independent variables for each smell under investigation

Test smell	Definition	Metric	Description	Structural/textual
Eager test	A test method involving many methods of the object being tested.	NMC	Number of method calls	Structural
		TMC	Test method cohesion, i.e., the average textual similarity between all the pairs methods called by a test method	Textual
		TS	Textual scattering, i.e., the extent to which the text within the method body is conceptually scattered	Textual
		NRF	Number of references to files	Structural
Mystery guest	A test that uses external resources (e.g., databases or files).	NRDB	Number of references to database	Structural
Resource optimism	A test that uses external resources without checking the state of these.	ERNC	State of external resources, which are not files, not checked	Structural
		FRNC	State of file resources not checked	Structural
		PR	Pair redundancy is the ratio between the items covered by a test and those covered by another one	Structural
Test redundancy	A test that could be removed without impacting the test suite.	SR	Suite redundancy is the ratio between the items covered by a test compared and those covered by all other tests in the test suite	Structural