diff --git a/tests/testthat/test-cache-as.R b/tests/testthat/test-cache-as.R
new file mode 100644
index 0000000..2a15b75
--- /dev/null
+++ b/tests/testthat/test-cache-as.R
@@ -0,0 +1,92 @@
+test_that("cacheAsFileName appends .rds where it is missing", {
+  expect_equal(RKorAPClient:::cacheAsFileName("analysis"), "analysis.rds")
+  expect_equal(RKorAPClient:::cacheAsFileName("analysis.rds"), "analysis.rds")
+  expect_equal(RKorAPClient:::cacheAsFileName("analysis.RDS"), "analysis.RDS")
+})
+
+test_that("a cache file is written and read back, without contacting the server", {
+  skip_if_offline()
+  kco <- KorAPConnection(accessToken = NULL, verbose = FALSE)
+  dir <- file.path(tempdir(), "cacheAsTest")
+  dir.create(dir, showWarnings = FALSE)
+  on.exit(unlink(dir, recursive = TRUE), add = TRUE)
+
+  # every query function that takes cacheAs, so that one added later without a
+  # cache file of its own does not go unnoticed
+  queries <- list(
+    "frequencyQuery" = function(f) frequencyQuery(kco, "Ameisenplage", cacheAs = f),
+    "corpusStats" = function(f) corpusStats(kco, vc = "pubDate since 2020", as.df = TRUE, cacheAs = f),
+    "collocationScoreQuery" = function(f) collocationScoreQuery(kco, "Grund", "triftiger", cacheAs = f),
+    "textMetadata" = function(f) textMetadata(kco, "WPD17/L79/98721", cacheAs = f)
+  )
+
+  for (name in names(queries)) {
+    query <- queries[[name]]
+    file <- file.path(dir, name)
+
+    fresh <- query(file)
+    expect_true(file.exists(paste0(file, ".rds")), info = name)
+
+    fromCache <- local({
+      testthat::local_mocked_bindings(
+        apiCall = function(...) stop("server must not be contacted"),
+        .package = "RKorAPClient"
+      )
+      query(file)
+    })
+    expect_equal(fromCache, fresh, info = name)
+
+    # what produced the result lives in the file only, not in the value
+    expect_null(attr(fromCache, RKorAPClient:::cacheAsAttribute), info = name)
+    expect_equal(
+      attr(readRDS(paste0(file, ".rds")), RKorAPClient:::cacheAsAttribute)$scoreVersion,
+      RKorAPClient:::cacheAsScoreVersion,
+      info = name
+    )
+  }
+})
+
+test_that("a cache file written before the scores were corrected is refused", {
+  skip_if_offline()
+  kco <- KorAPConnection(accessToken = NULL, verbose = FALSE)
+  file <- tempfile(fileext = ".rds")
+  on.exit(unlink(file), add = TRUE)
+
+  frequencyQuery(kco, "Ameisenplage", cacheAs = file)
+  aged <- readRDS(file)
+  record <- attr(aged, RKorAPClient:::cacheAsAttribute)
+  # as a file from before the corrections has it: an older score generation, and
+  # an older version to go with it
+  record$scoreVersion <- "1.3.0"
+  record$packageVersion <- "1.3.0"
+  attr(aged, RKorAPClient:::cacheAsAttribute) <- record
+  saveRDS(aged, file)
+
+  expect_warning(frequencyQuery(kco, "Ameisenplage", cacheAs = file), "1\\.3\\.0")
+  # and the refused file is replaced by a current one, so the warning comes once
+  expect_silent(frequencyQuery(kco, "Ameisenplage", cacheAs = file))
+})
+
+test_that("a query that differs is recomputed rather than read back", {
+  skip_if_offline()
+  kco <- KorAPConnection(accessToken = NULL, verbose = FALSE)
+  file <- tempfile(fileext = ".rds")
+  on.exit(unlink(file), add = TRUE)
+
+  frequencyQuery(kco, "Ameisenplage", cacheAs = file)
+  expect_warning(frequencyQuery(kco, "Heuschreckenplage", cacheAs = file), "query")
+})
+
+test_that("verbosity is not part of what a cache file records", {
+  skip_if_offline()
+  kco <- KorAPConnection(accessToken = NULL, verbose = FALSE)
+  file <- tempfile(fileext = ".rds")
+  on.exit(unlink(file), add = TRUE)
+
+  corpusStats(kco, vc = "pubDate since 2020", as.df = TRUE, cacheAs = file)
+  # how loud a query is does not change what it returns, so it must not make
+  # the file be thrown away
+  expect_silent(
+    corpusStats(kco, vc = "pubDate since 2020", as.df = TRUE, verbose = TRUE, cacheAs = file)
+  )
+})