2 files changed, 129 insertions, 0 deletions

diff --git a/crates/assists/src/handlers/replace_string_with_char.rs b/crates/assists/src/handlers/replace_string_with_char.rs
new file mode 100644
index 000000000..3dc19431c
--- /dev/null
+++ b/crates/assists/src/handlers/replace_string_with_char.rs
@@ -0,0 +1,127 @@
+use std::borrow::Cow;
+
+use syntax::{
+    ast::{self, HasQuotes, HasStringValue},
+    AstToken,
+    SyntaxKind::{RAW_STRING, STRING},
+    TextRange, TextSize,
+};
+use test_utils::mark;
+
+use crate::{AssistContext, AssistId, AssistKind, Assists};
+
+// Assist: replace_string_with_char
+//
+// Replace string with char
+//
+// ```
+// fn main() {
+//     find("{<|>");
+// }
+// ```
+// ->
+// ```
+// fn main() {
+//     find('{');
+// }
+// ```
+pub(crate) fn replace_string_with_char(acc: &mut Assists, ctx: &AssistContext) -> Option<()> {
+    let token = ctx.find_token_at_offset(STRING).and_then(ast::String::cast)?;
+    let value = token.value()?;
+    let target = token.syntax().text_range();
+    if value.len() > 1 || value.is_empty() {
+        return None;
+    }
+
+    acc.add(
+        AssistId("replace_string_with_char", AssistKind::RefactorRewrite),
+        "Replace string with char",
+        target,
+        |edit| {
+            edit.replace(token.syntax().text_range(), format!("'{}'", value));
+        },
+    )
+}
+
+#[cfg(test)]
+mod tests {
+    use crate::tests::{check_assist, check_assist_not_applicable, check_assist_target};
+
+    use super::*;
+
+    #[test]
+    fn replace_string_with_char_target() {
+        check_assist_target(
+            replace_string_with_char,
+            r#"
+            fn f() {
+                let s = "<|>c";
+            }
+            "#,
+            r#""c""#,
+        );
+    }
+
+    #[test]
+    fn replace_string_with_char_assist() {
+        check_assist(
+            replace_string_with_char,
+            r#"
+    fn f() {
+        let s = "<|>c";
+    }
+    "#,
+            r##"
+    fn f() {
+        let s = 'c';
+    }
+    "##,
+        )
+    }
+
+    #[test]
+    fn replace_string_with_char_assist_not_applicable() {
+        check_assist_not_applicable(
+            replace_string_with_char,
+            r#"
+    fn f() {
+        let s = "<|>test";
+    }
+    "#,
+        )
+    }
+
+    #[test]
+    fn replace_string_with_char_works_inside_macros() {
+        check_assist(
+            replace_string_with_char,
+            r#"
+                fn f() {
+                    format!(<|>"x", 92)
+                }
+                "#,
+            r##"
+                fn f() {
+                    format!('x', 92)
+                }
+                "##,
+        )
+    }
+
+    #[test]
+    fn replace_string_with_char_works_func_args() {
+        check_assist(
+            replace_string_with_char,
+            r#"
+                fn f() {
+                    find(<|>"x");
+                }
+                "#,
+            r##"
+                fn f() {
+                    find('x');
+                }
+                "##,
+        )
+    }
+}
diff --git a/crates/assists/src/lib.rs b/crates/assists/src/lib.rs
index a2bec818c..2a98cccc0 100644
--- a/crates/assists/src/lib.rs
+++ b/crates/assists/src/lib.rs
@@ -159,6 +159,7 @@ mod handlers {
     mod replace_impl_trait_with_generic;
     mod replace_let_with_if_let;
     mod replace_qualified_name_with_use;
+    mod replace_string_with_char;
     mod replace_unwrap_with_match;
     mod split_import;
     mod unwrap_block;
@@ -208,6 +209,7 @@ mod handlers {
             replace_impl_trait_with_generic::replace_impl_trait_with_generic,
             replace_let_with_if_let::replace_let_with_if_let,
             replace_qualified_name_with_use::replace_qualified_name_with_use,
+            replace_string_with_char::replace_string_with_char,
             replace_unwrap_with_match::replace_unwrap_with_match,
             split_import::split_import,
             unwrap_block::unwrap_block,