Made tests more explanatory, and added test checking for correlations themselves.

Author: kenmawer

tests/testthat/test-correlation.R

@@ -1,6 +1,6 @@
 library(tibble)
 
-test_that("epi_cor throws an error for a non-epi df for its first argument",{
+test_that("epi_cor throws an error for a non-epi_df for its first argument",{
   expect_error(epi_cor(1:10,1,1))
   expect_error(epi_cor(data.frame(x=1:10),1,1))
 })
@@ -10,17 +10,24 @@ test_that("epi_cor requires two var arguments, var1 and var2",{
   expect_error(epi_cor(archive_cases_dv_subset$DT,var1=1))
 })
 
-test_that("epi_cor functions as it should",{
+test_that("epi_cor functions as intended",{
   expect_equal(epi_cor(x = jhu_csse_daily_subset, 
                var1 = case_rate_7d_av, 
                var2 = death_rate_7d_av, 
                cor_by = geo_value, 
                dt1 = -2)[1],
                tibble(geo_value = unique(jhu_csse_daily_subset$geo_value))
   )
+  
+  edf <- as_epi_df(data.frame(geo_value=rep("asdf",20),
+                              time_value=as.Date("2020-01-01") + 1:20,
+                              pos=1:20,
+                              neg=-(1:20)))
+  expect_equal(epi_cor(edf, pos, pos)[[2]],1)
+  expect_equal(epi_cor(edf, pos, neg)[[2]],-1)
 })
 
-test_that("shift works as it should",{
+test_that("shift works as intended",{
   expect_identical(shift(1:100,1),dplyr::lead(1:100))
   expect_identical(shift(1:100,0),1:100)
   expect_identical(shift(1:100,-1),dplyr::lag(1:100))