require non-empty strings for test description

NEWS.md

@@ -1,5 +1,8 @@
 # testthat (development version)
 
+* `test_that()` now emits an error if `expect_snapshot()` is invoked within
+  a `test_that()` case with an empty description (#1980; @kevinushey).
+
 # testthat 3.2.1
 
 * Fix incorrect format string detected by latest R-devel. Fix thanks to 

R/snapshot-reporter.R

@@ -46,6 +46,7 @@ SnapshotReporter <- R6::R6Class("SnapshotReporter",
                              tolerance = testthat_tolerance(),
                              variant = NULL,
                              trace_env = NULL) {
+      check_string(self$test, allow_empty = FALSE)
       i <- self$new_snaps$append(self$test, variant, save(value))
 
       old_raw <- self$old_snaps$get(self$test, variant, i)

tests/testthat/test-snapshot.R

@@ -162,3 +162,11 @@ test_that("hint is informative", {
     cat(snapshot_accept_hint("foo", "bar.R", reset_output = FALSE))
   })
 })
+
+test_that("expect_snapshot requires a non-empty test label", {
+
+  test_that("", {
+    expect_error(expect_snapshot(1 + 1))
+  })
+
+})