adding test patterns

Author: kyoto7250

tests/ui/bytes_count_to_len.rs

@@ -1,15 +1,34 @@
+// run-rustfix
 #![warn(clippy::bytes_count_to_len)]
+use std::fs::File;
+use std::io::Read;
 
 fn main() {
-    let s1 = String::from("world");
+    // should fix, because type is String
+    let _ = String::from("foo").bytes().count();
 
-    //test warning against a string literal
-    "hello".bytes().count();
+    let s1 = String::from("foo");
+    let _ = s1.bytes().count();
 
-    //test warning against a string variable
-    s1.bytes().count();
+    // should fix, because type is &str
+    let _ = "foo".bytes().count();
 
-    //make sure using count() normally doesn't trigger warning
+    let s2 = "foo";
+    let _ = s2.bytes().count();
+
+    // make sure using count() normally doesn't trigger warning
     let vector = [0, 1, 2];
-    let size = vector.iter().count();
+    let _ = vector.iter().count();
+
+    // should not fix, because type is slice.
+    let _ = &[1, 2, 3].bytes().count();
+
+    let bytes: &[u8] = &[1, 2, 3];
+    bytes.bytes().count();
+
+    // should not fix, because type is File.
+    let _ = File::open("foobar").unwrap().bytes().count();
+
+    let f = File::open("foobar").unwrap();
+    let _ = f.bytes().count();
 }