-output=$(test_emacs '(notmuch-search "*") (notmuch-test-wait) (princ (buffer-string))' | sed -e s', *, ,g' -e 's/xxx*/[BLOB]/g')
-test_expect_equal "$output" "$expected"
+test_emacs '(notmuch-search "*")
+ (notmuch-test-wait)
+ (test-output)'
+sed -i -e s', *, ,g' -e 's/xxx*/[BLOB]/g' OUTPUT
+test_expect_equal_file OUTPUT EXPECTED