Add tests and docs

This adds test to make sure correct behavior of lint
- The first test's option variable is not a temporary variable
- The second test does not make usage of `take()`
- The third test makes usage of `take()` and uses a temporary variable

Author: infrandomness

clippy_lints/src/methods/mod.rs

@@ -2169,11 +2169,13 @@ declare_clippy_lint! {
     ///
     /// ### Example
     /// ```rust
-    /// // example code where clippy issues a warning
+    /// let x = Some(3);
+    /// x.as_ref().take();
     /// ```
     /// Use instead:
     /// ```rust
-    /// // example code which does not raise clippy warning
+    /// let x = Some(3);
+    /// x.as_ref();
     /// ```
     #[clippy::version = "1.61.0"]
     pub NEEDLESS_OPTION_TAKE,

tests/ui/needless_option_take.rs

@@ -1,7 +1,15 @@
 // run-rustfix
 
 fn main() {
-    println!("Testing option_take_on_temporary");
+    println!("Testing non erroneous option_take_on_temporary");
+    let mut option = Some(1);
+    let _ = Box::new(move || option.take().unwrap());
+
+    println!("Testing non erroneous option_take_on_temporary");
+    let x = Some(3);
+    x.as_ref();
+
+    println!("Testing erroneous option_take_on_temporary");
     let x = Some(3);
     x.as_ref().take();
 }

tests/ui/option_take_on_temporary.fixed

@@ -1,7 +1,15 @@
 // run-rustfix
 
 fn main() {
-    println!("Testing option_take_on_temporary");
+    println!("Testing non erroneous option_take_on_temporary");
+    let mut option = Some(1);
+    let _ = Box::new(move || option.take().unwrap());
+
+    println!("Testing non erroneous option_take_on_temporary");
+    let x = Some(3);
+    x.as_ref();
+
+    println!("Testing erroneous option_take_on_temporary");
     let x = Some(3);
     x.as_ref();
 }