Added a lint as suggested in 6010 which recommends using contains()

instead of `find()` follows by `is_some()` on strings

Update clippy_lints/src/find_is_some_on_strs.rs
Co-authored-by: Takayuki Nakata <f.seasons017@gmail.com>

Update clippy_lints/src/methods/mod.rs
Co-authored-by: Philipp Krones <hello@philkrones.com>

tests/ui/methods.rs

@@ -168,8 +168,27 @@ fn search_is_some() {
                                    x < 0
                                }
                    ).is_some();
+    
+    let s1 = String::from("hello world");
+    let s2 = String::from("world");
+    // Check caller `find()` is a &`static str case
+    let _ = "hello world".find("world").is_some();
+    let _ = "hello world".find(&s2).is_some();
+    let _ = "hello world".find(&s2[2..]).is_some();
+    // Check caller of `find()` is a String case
+    let _ = s1.find("world").is_some();
+    let _ = s1.find(&s2).is_some();
+    let _ = s1.find(&s2[2..]).is_some();
+    //  Check caller of `find()` is a slice of String case
+    let _ = s1[2..].find("world").is_some();
+    let _ = s1[2..].find(&s2).is_some();
+    let _ = s1[2..].find(&s2[2..]).is_some();
 
-    // Check that we don't lint if the caller is not an `Iterator`.
+    // Check that we don't lint if `find()` is called with
+    // Pattern that is not a string
+    let _ = s1.find(|c: char| c == 'o' || c == 'l').is_some();
+
+    // Check that we don't lint if the caller is not an `Iterator` or string
     let foo = IteratorFalsePositives { foo: 0 };
     let _ = foo.find().is_some();
     let _ = foo.position().is_some();

tests/ui/methods.stderr

@@ -88,5 +88,3 @@ LL | |                                }
 LL | |                    ).is_some();
    | |______________________________^
 
-error: aborting due to 11 previous errors
-