test_summarize: a function of two arguments (continuous variable and grouping variable), used to compare continuous variable. Must return a list of two components: p.value and method. See test_summarize_auto or test_summarize_linear_contrasts for some examples of such functions.
test_tabular: a function of two arguments (two categorical variables), used to test association between two categorical variables. Must return a list of two components: p.value and method. See test_tabular_auto for example.
test_correlation: a function of three arguments (two continuous variables plus the correlation method), used to test association between two continuous variables. Like cor.test, it must return a list of at least estimate, p.value, and method, with also conf.int optionally. See test_correlation_auto for example.
test_survival: a function of one argument (the formula surv~by), used to compare survival estimations. Must return a list of two components: p.value and method. See test_survival_logrank for example.
test_display: function used to display the test result. See display_test.
plim: number of digits for the p value.
show_method: whether to display the test name (logical).