Closes # 2581 enhance test coverage: derive_var_trtemfl() (#2617)

* # 2581 enhance test coverage: derive_var_trtemfl()

- Test # 10, fix typo
- Test # 11, new test to increase coverage

* # 2581 coverage derive_var_trtemfl, Test #11 add

* git checkout 49a2b19d1 -- admiral.Rproj;  should (1) replace admiral.Rproj as it was in commit 49a2b19d1 and (2) make commit, so older history is not changed

tests/testthat/_snaps/derive_var_trtemfl.md

@@ -34,10 +34,10 @@
       ! `intensity` argument was specified but not `initial_intensity`
       Either both or none of them must be specified.
 
-# derive_var_trtemfl Test 11: error if `group_var` without `subject_keys`
+# derive_var_trtemfl Test 11: error if `group_var` specified without `subject_keys`
 
     Code
-      derive_var_trtemfl(adae, group_var = AEGRPID, subject_keys = NULL)
+      derive_var_trtemfl(adae2, group_var = AEGRPID, subject_keys = NULL)
     Condition
       Error in `derive_var_trtemfl()`:
       ! `group_var` argument was specified but not `subject_keys`

tests/testthat/test-derive_var_trtemfl.R

@@ -205,11 +205,11 @@ test_that("derive_var_trtemfl Test 10: error if `intensity` without `initial_int
   )
 })
 
-## Test 11: error if `group_var` are specified without `subject_keys` ----
-test_that("derive_var_trtemfl Test 11: error if `group_var` without `subject_keys`", {
+## Test 11: error if `group_var` specified without `subject_keys` ----
+test_that("derive_var_trtemfl Test 11: error if `group_var` specified without `subject_keys`", {
   expect_snapshot(
     derive_var_trtemfl(
-      adae,
+      adae2,
       group_var = AEGRPID,
       subject_keys = NULL
     ),