From ed0d93d5401b0b13d1aae2c6c7cd0d451d6ec5a0 Mon Sep 17 00:00:00 2001
From: Michael Chirico <michaelchirico4@gmail.com>
Date: Thu, 2 May 2024 22:25:54 -0700
Subject: [PATCH] lint-test-literal

---
 .ci/linters/dt_test_literal_linter.R | 10 ++++++++++
 inst/tests/tests.Rraw                |  2 +-
 2 files changed, 11 insertions(+), 1 deletion(-)
 create mode 100644 .ci/linters/dt_test_literal_linter.R

diff --git a/.ci/linters/dt_test_literal_linter.R b/.ci/linters/dt_test_literal_linter.R
new file mode 100644
index 000000000..fa07d068a
--- /dev/null
+++ b/.ci/linters/dt_test_literal_linter.R
@@ -0,0 +1,10 @@
+# Avoid test(SYMBOL) and test(SYMBOL+...) except in rare cases.
+#   in the latter case, prefer test(NUMBER+expr).
+dt_test_literal_linter <- lintr::make_linter_from_xpath(
+  "
+    //SYMBOL_FUNCTION_CALL[text() = 'test']
+      /parent::expr
+      /following-sibling::expr[1][SYMBOL or expr[1]/SYMBOL]
+  ",
+  "Prefer test's 'num' argument to start with a numeric literal except in rare cases, e.g. test(123, ...) or test(123+x/6, ...)"
+)
diff --git a/inst/tests/tests.Rraw b/inst/tests/tests.Rraw
index 68f12bd2b..7bc8b2ad8 100644
--- a/inst/tests/tests.Rraw
+++ b/inst/tests/tests.Rraw
@@ -9769,7 +9769,7 @@ nqjoin_test <- function(x, y, k=1L, test_no, mult="all") {
     ans1 = nq(x, y, thiscols, thisops, 0L, mult=mult)
     ans2 = check(x, y, thiscols, thisops, mult=mult)
     test_no = test_no + .001
-    test(test_no, ans1, ans2)
+    test(test_no, ans1, ans2) # nolint: dt_test_literal_linter.
   }
   gc()  # no longer needed but left in place just in case, no harm
 }