test: add cfg_not_test tests

tests/ui/cfg_not_test.rs

@@ -0,0 +1,32 @@
+#![allow(unused)]
+#![warn(clippy::cfg_not_test)]
+
+fn important_check() {}
+
+fn main() {
+    // Statement
+    #[cfg(not(test))]
+    let answer = 42;
+
+    // Expression
+    #[cfg(not(test))]
+    important_check();
+
+    // Make sure only not(test) are checked, not other attributes
+    #[cfg(not(foo))]
+    important_check();
+}
+
+#[cfg(not(not(test)))]
+struct CfgNotTest;
+
+// Deeply nested `not(test)`
+#[cfg(not(test))]
+fn foo() {}
+#[cfg(all(debug_assertions, not(test)))]
+fn bar() {}
+#[cfg(not(any(not(debug_assertions), test)))]
+fn baz() {}
+
+#[cfg(test)]
+mod tests {}

tests/ui/cfg_not_test.stderr

@@ -0,0 +1,45 @@
+error: code is excluded from test builds
+  --> tests/ui/cfg_not_test.rs:8:5
+   |
+LL |     #[cfg(not(test))]
+   |     ^^^^^^^^^^^^^^^^^
+   |
+   = help: consider not excluding any code from test builds
+   = note: this could increase code coverage despite not actually being tested
+   = note: `-D clippy::cfg-not-test` implied by `-D warnings`
+   = help: to override `-D warnings` add `#[allow(clippy::cfg_not_test)]`
+
+error: code is excluded from test builds
+  --> tests/ui/cfg_not_test.rs:12:5
+   |
+LL |     #[cfg(not(test))]
+   |     ^^^^^^^^^^^^^^^^^
+   |
+   = help: consider not excluding any code from test builds
+
+error: code is excluded from test builds
+  --> tests/ui/cfg_not_test.rs:24:1
+   |
+LL | #[cfg(not(test))]
+   | ^^^^^^^^^^^^^^^^^
+   |
+   = help: consider not excluding any code from test builds
+
+error: code is excluded from test builds
+  --> tests/ui/cfg_not_test.rs:26:1
+   |
+LL | #[cfg(all(debug_assertions, not(test)))]
+   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+   |
+   = help: consider not excluding any code from test builds
+
+error: code is excluded from test builds
+  --> tests/ui/cfg_not_test.rs:28:1
+   |
+LL | #[cfg(not(any(not(debug_assertions), test)))]
+   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+   |
+   = help: consider not excluding any code from test builds
+
+error: aborting due to 5 previous errors
+