add tests

tests/testthat/test-03-combine.R

@@ -0,0 +1,23 @@
+x <- combine_docs("resolution")
+
+test_that("gets resolutions only", {
+  expect_equal(unique(x$type), "resolution")
+})
+
+
+test_that("output has 6 columns", {
+  expect_equal(ncol(x), 6)
+})
+
+
+x <- combine_iatf(res = 9:12)
+
+test_that("resolutions 9 to 12 are retrieved", {
+  expect_equal(unique(x$id), 9:12)
+})
+
+test_that("source is iatf", {
+  expect_equal(unique(x$source), "IATF")
+})
+
+