2 files changed, 33 insertions, 1 deletions
diff --git a/tests/ui/collection_is_never_read.rs b/tests/ui/collection_is_never_read.rs
index 068a49486cf..ca20031bfbe 100644
--- a/tests/ui/collection_is_never_read.rs
+++ b/tests/ui/collection_is_never_read.rs
@@ -163,3 +163,23 @@ fn function_argument() {
     let x = vec![1, 2, 3]; // Ok
     foo(&x);
 }
+
+fn string() {
+    // Do lint (write without read)
+    let mut s = String::new();
+    s.push_str("Hello, World!");
+
+    // Do not lint (read without write)
+    let mut s = String::from("Hello, World!");
+    let _ = s.len();
+
+    // Do not lint (write and read)
+    let mut s = String::from("Hello, World!");
+    s.push_str("foo, bar");
+    let _ = s.len();
+
+    // Do lint the first line, but not the second
+    let mut s = String::from("Hello, World!");
+    let t = String::from("foo, bar");
+    s = t;
+}
diff --git a/tests/ui/collection_is_never_read.stderr b/tests/ui/collection_is_never_read.stderr
index 7654b74be3d..f5dea96116f 100644
--- a/tests/ui/collection_is_never_read.stderr
+++ b/tests/ui/collection_is_never_read.stderr
@@ -48,5 +48,17 @@ error: collection is never read
 LL |     let x = vec![1, 2, 3]; // WARNING
    |     ^^^^^^^^^^^^^^^^^^^^^^
 
-error: aborting due to 8 previous errors
+error: collection is never read
+  --> $DIR/collection_is_never_read.rs:169:5
+   |
+LL |     let mut s = String::new();
+   |     ^^^^^^^^^^^^^^^^^^^^^^^^^^
+
+error: collection is never read
+  --> $DIR/collection_is_never_read.rs:182:5
+   |
+LL |     let mut s = String::from("Hello, World!");
+   |     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+
+error: aborting due to 10 previous errors