Write the correct test'

internal/datastore/proxy/schemacaching/standardcaching_test.go

@@ -531,20 +531,19 @@ func TestInvalidEntriesInCache(t *testing.T) {
 
 	headRevision, err := ds.HeadRevision(ctx)
 	require.NoError(err)
-	var dsReader definitionCachingReader
-	dsReader = ds.SnapshotReader(headRevision)
-
-	// Lookup an invalid name
-	readerReturningNil := func(ctx context.Context, names []string) ([]datastore.RevisionedNamespace, error) {
-			return []datastore.RevisionedNamespace{{nil, nil}}, nil
-		}
-	found, err := listAndCache(ctx, &dsReader, namespaceCacheKeyPrefix, []string{invalidNamespace}, readerReturningNil, estimatedNamespaceDefinitionSize)
-	require.Empty(found)
-	require.NoError(err)
+	dsReader := ds.SnapshotReader(headRevision)
+
+	namespace, _, err := dsReader.ReadNamespaceByName(ctx, invalidNamespace)
+	require.Nil(namespace)
+	// NOTE: we're expecting this to error, because the namespace doesn't exist.
+	// However, the act of calling it sets the cache value to nil, which means that
+	// subsequent calls to the cache return that nil value. That's what needed to
+	// be filtered out of the list call.
+	require.Error(err)
 
 	// Look it up again - in the bug that this captures,
 	// it was populated into the cache and came back out.
-	found, err = dsReader.LookupNamespacesWithNames()
+	found, err := dsReader.LookupNamespacesWithNames(ctx, []string{invalidNamespace})
 	require.Empty(found)
 	require.NoError(err)
 }