# compute the probability by integration
# compute the probability by integration
integrate(df, lower = 1, upper = 10, df1 = 4, df2 = 5)$value
test_function("integrate", args = c("f", "lower", "upper", "df1", "df2"))
test_output_contains("integrate(df, lower = 1, upper = 10, df1 = 4, df2 = 5)$value")