1 files changed, 134 insertions, 0 deletions
diff --git a/src/tools/clippy/tests/ui/seek_to_start_instead_of_rewind.rs b/src/tools/clippy/tests/ui/seek_to_start_instead_of_rewind.rs
new file mode 100644
index 000000000..c5bc57cc3
--- /dev/null
+++ b/src/tools/clippy/tests/ui/seek_to_start_instead_of_rewind.rs
@@ -0,0 +1,134 @@
+// run-rustfix
+#![allow(unused)]
+#![warn(clippy::seek_to_start_instead_of_rewind)]
+
+use std::fs::OpenOptions;
+use std::io::{Read, Seek, SeekFrom, Write};
+
+struct StructWithSeekMethod {}
+
+impl StructWithSeekMethod {
+    fn seek(&mut self, from: SeekFrom) {}
+}
+
+trait MySeekTrait {
+    fn seek(&mut self, from: SeekFrom) {}
+}
+
+struct StructWithSeekTrait {}
+impl MySeekTrait for StructWithSeekTrait {}
+
+// This should NOT trigger clippy warning because
+// StructWithSeekMethod does not implement std::io::Seek;
+fn seek_to_start_false_method(t: &mut StructWithSeekMethod) {
+    t.seek(SeekFrom::Start(0));
+}
+
+// This should NOT trigger clippy warning because
+// StructWithSeekMethod does not implement std::io::Seek;
+fn seek_to_start_method_owned_false<T>(mut t: StructWithSeekMethod) {
+    t.seek(SeekFrom::Start(0));
+}
+
+// This should NOT trigger clippy warning because
+// StructWithSeekMethod does not implement std::io::Seek;
+fn seek_to_start_false_trait(t: &mut StructWithSeekTrait) {
+    t.seek(SeekFrom::Start(0));
+}
+
+// This should NOT trigger clippy warning because
+// StructWithSeekMethod does not implement std::io::Seek;
+fn seek_to_start_false_trait_owned<T>(mut t: StructWithSeekTrait) {
+    t.seek(SeekFrom::Start(0));
+}
+
+// This should NOT trigger clippy warning because
+// StructWithSeekMethod does not implement std::io::Seek;
+fn seek_to_start_false_trait_bound<T: MySeekTrait>(t: &mut T) {
+    t.seek(SeekFrom::Start(0));
+}
+
+// This should trigger clippy warning
+fn seek_to_start<T: Seek>(t: &mut T) {
+    t.seek(SeekFrom::Start(0));
+}
+
+// This should trigger clippy warning
+fn owned_seek_to_start<T: Seek>(mut t: T) {
+    t.seek(SeekFrom::Start(0));
+}
+
+// This should NOT trigger clippy warning because
+// it does not seek to start
+fn seek_to_5<T: Seek>(t: &mut T) {
+    t.seek(SeekFrom::Start(5));
+}
+
+// This should NOT trigger clippy warning because
+// it does not seek to start
+fn seek_to_end<T: Seek>(t: &mut T) {
+    t.seek(SeekFrom::End(0));
+}
+
+fn main() {
+    let mut f = OpenOptions::new()
+        .write(true)
+        .read(true)
+        .create(true)
+        .open("foo.txt")
+        .unwrap();
+
+    let mut my_struct_trait = StructWithSeekTrait {};
+    seek_to_start_false_trait_bound(&mut my_struct_trait);
+
+    let hello = "Hello!\n";
+    write!(f, "{hello}").unwrap();
+    seek_to_5(&mut f);
+    seek_to_end(&mut f);
+    seek_to_start(&mut f);
+
+    let mut buf = String::new();
+    f.read_to_string(&mut buf).unwrap();
+
+    assert_eq!(&buf, hello);
+}
+
+#[clippy::msrv = "1.54"]
+fn msrv_1_54() {
+    let mut f = OpenOptions::new()
+        .write(true)
+        .read(true)
+        .create(true)
+        .open("foo.txt")
+        .unwrap();
+
+    let hello = "Hello!\n";
+    write!(f, "{hello}").unwrap();
+
+    f.seek(SeekFrom::Start(0));
+
+    let mut buf = String::new();
+    f.read_to_string(&mut buf).unwrap();
+
+    assert_eq!(&buf, hello);
+}
+
+#[clippy::msrv = "1.55"]
+fn msrv_1_55() {
+    let mut f = OpenOptions::new()
+        .write(true)
+        .read(true)
+        .create(true)
+        .open("foo.txt")
+        .unwrap();
+
+    let hello = "Hello!\n";
+    write!(f, "{hello}").unwrap();
+
+    f.seek(SeekFrom::Start(0));
+
+    let mut buf = String::new();
+    f.read_to_string(&mut buf).unwrap();
+
+    assert_eq!(&buf, hello);
+}