Add unit test for s3

DESCRIPTION

@@ -22,7 +22,8 @@ Suggests:
     BiocStyle,
     covr,
     knitr,
-    tinytest
+    tinytest,
+    mockery
 VignetteBuilder: knitr
 SystemRequirements: GNU make
 biocViews: DataImport

inst/tinytest/test_roundtrip.R

@@ -92,3 +92,4 @@ expect_silent(
     )
 )
 expect_identical(read_zarr_array(path), x)
+

inst/tinytest/test_s3.R

@@ -0,0 +1,15 @@
+path <- "https://www.test.com/bucket/file1"
+s3_client <- Rarr:::.create_s3_client(path)
+
+if(require(mockery)) {
+
+  ## This ensures .get_credentials always returns an error, even if the 
+  ## host machine has credentials available
+  stub(where = Rarr:::.create_s3_client, 
+       what = '.get_credentials',
+       how = function(...) stop(), 
+       depth = 2)
+
+  ## we expect an "anonymous" credential if nothing is found  
+  expect_true(s3_client$.internal$config$credentials$anonymous)
+}