1 files changed, 91 insertions, 0 deletions
diff --git a/tests/ui/trim_split_whitespace.fixed b/tests/ui/trim_split_whitespace.fixed
new file mode 100644
index 00000000000..e4d352f7367
--- /dev/null
+++ b/tests/ui/trim_split_whitespace.fixed
@@ -0,0 +1,91 @@
+// run-rustfix
+#![warn(clippy::trim_split_whitespace)]
+#![allow(clippy::let_unit_value)]
+
+struct Custom;
+impl Custom {
+    fn trim(self) -> Self {
+        self
+    }
+    fn split_whitespace(self) {}
+}
+
+struct DerefStr(&'static str);
+impl std::ops::Deref for DerefStr {
+    type Target = str;
+    fn deref(&self) -> &Self::Target {
+        self.0
+    }
+}
+
+struct DerefStrAndCustom(&'static str);
+impl std::ops::Deref for DerefStrAndCustom {
+    type Target = str;
+    fn deref(&self) -> &Self::Target {
+        self.0
+    }
+}
+impl DerefStrAndCustom {
+    fn trim(self) -> Self {
+        self
+    }
+    fn split_whitespace(self) {}
+}
+
+struct DerefStrAndCustomSplit(&'static str);
+impl std::ops::Deref for DerefStrAndCustomSplit {
+    type Target = str;
+    fn deref(&self) -> &Self::Target {
+        self.0
+    }
+}
+impl DerefStrAndCustomSplit {
+    #[allow(dead_code)]
+    fn split_whitespace(self) {}
+}
+
+struct DerefStrAndCustomTrim(&'static str);
+impl std::ops::Deref for DerefStrAndCustomTrim {
+    type Target = str;
+    fn deref(&self) -> &Self::Target {
+        self.0
+    }
+}
+impl DerefStrAndCustomTrim {
+    fn trim(self) -> Self {
+        self
+    }
+}
+
+fn main() {
+    // &str
+    let _ = " A B C ".split_whitespace(); // should trigger lint
+    let _ = " A B C ".split_whitespace(); // should trigger lint
+    let _ = " A B C ".split_whitespace(); // should trigger lint
+
+    // String
+    let _ = (" A B C ").to_string().split_whitespace(); // should trigger lint
+    let _ = (" A B C ").to_string().split_whitespace(); // should trigger lint
+    let _ = (" A B C ").to_string().split_whitespace(); // should trigger lint
+
+    // Custom
+    let _ = Custom.trim().split_whitespace(); // should not trigger lint
+
+    // Deref<Target=str>
+    let s = DerefStr(" A B C ");
+    let _ = s.split_whitespace(); // should trigger lint
+
+    // Deref<Target=str> + custom impl
+    let s = DerefStrAndCustom(" A B C ");
+    let _ = s.trim().split_whitespace(); // should not trigger lint
+
+    // Deref<Target=str> + only custom split_ws() impl
+    let s = DerefStrAndCustomSplit(" A B C ");
+    let _ = s.split_whitespace(); // should trigger lint
+    // Expl: trim() is called on str (deref) and returns &str.
+    //       Thus split_ws() is called on str as well and the custom impl on S is unused
+
+    // Deref<Target=str> + only custom trim() impl
+    let s = DerefStrAndCustomTrim(" A B C ");
+    let _ = s.trim().split_whitespace(); // should not trigger lint
+}