Fix not applicable on and for replace_method_eager_lazy

Supports:

- and <-> and_then
- then_some <-> then

Example
---
```rust
fn foo() {
    let foo = Some("foo");
    return foo.and$0(Some("bar"));
}
```

**Before this PR**

Assist not applicable

**After this PR**

```rust
fn foo() {
    let foo = Some("foo");
    return foo.and_then(|| Some("bar"));
}
```

Author: A4-Tacks

crates/ide-assists/src/handlers/replace_method_eager_lazy.rs

@@ -35,10 +35,7 @@ pub(crate) fn replace_with_lazy_method(acc: &mut Assists, ctx: &AssistContext<'_
     let (_, receiver_ty) = callable.receiver_param(ctx.sema.db)?;
     let n_params = callable.n_params() + 1;
 
-    let method_name_lazy = format!(
-        "{method_name}{}",
-        if method_name.text().ends_with("or") { "_else" } else { "_with" }
-    );
+    let method_name_lazy = lazy_method_name(&method_name.text());
 
     receiver_ty.iterate_method_candidates_with_traits(
         ctx.sema.db,
@@ -71,6 +68,18 @@ pub(crate) fn replace_with_lazy_method(acc: &mut Assists, ctx: &AssistContext<'_
     )
 }
 
+fn lazy_method_name(name: &str) -> String {
+    if ends_is(name, "or") {
+        format!("{name}_else")
+    } else if ends_is(name, "and") {
+        format!("{name}_then")
+    } else if ends_is(name, "then_some") {
+        name.strip_suffix("_some").unwrap().to_owned()
+    } else {
+        format!("{name}_with")
+    }
+}
+
 fn into_closure(param: &Expr) -> Expr {
     (|| {
         if let ast::Expr::CallExpr(call) = param {
@@ -118,9 +127,7 @@ pub(crate) fn replace_with_eager_method(acc: &mut Assists, ctx: &AssistContext<'
     }
 
     let method_name_text = method_name.text();
-    let method_name_eager = method_name_text
-        .strip_suffix("_else")
-        .or_else(|| method_name_text.strip_suffix("_with"))?;
+    let method_name_eager = eager_method_name(&method_name_text)?;
 
     receiver_ty.iterate_method_candidates_with_traits(
         ctx.sema.db,
@@ -158,6 +165,20 @@ fn into_call(param: &Expr) -> Expr {
     .unwrap_or_else(|| make::expr_call(param.clone(), make::arg_list(Vec::new())).into())
 }
 
+fn eager_method_name(name: &str) -> Option<&str> {
+    if name == "then" {
+        return Some("then_some");
+    }
+
+    name.strip_suffix("_else")
+        .or_else(|| name.strip_suffix("_then"))
+        .or_else(|| name.strip_suffix("_with"))
+}
+
+fn ends_is(name: &str, end: &str) -> bool {
+    name.strip_suffix(end).is_some_and(|s| s.is_empty() || s.ends_with('_'))
+}
+
 #[cfg(test)]
 mod tests {
     use crate::tests::check_assist;
@@ -296,6 +317,86 @@ fn foo() {
     let foo = Some("foo");
     return foo.map_or(42, |v| v.len());
 }
+"#,
+        )
+    }
+
+    #[test]
+    fn replace_and_with_and_then() {
+        check_assist(
+            replace_with_lazy_method,
+            r#"
+//- minicore: option, fn
+fn foo() {
+    let foo = Some("foo");
+    return foo.and$0(Some("bar"));
+}
+"#,
+            r#"
+fn foo() {
+    let foo = Some("foo");
+    return foo.and_then(|| Some("bar"));
+}
+"#,
+        )
+    }
+
+    #[test]
+    fn replace_and_then_with_and() {
+        check_assist(
+            replace_with_eager_method,
+            r#"
+//- minicore: option, fn
+fn foo() {
+    let foo = Some("foo");
+    return foo.and_then$0(|| Some("bar"));
+}
+"#,
+            r#"
+fn foo() {
+    let foo = Some("foo");
+    return foo.and(Some("bar"));
+}
+"#,
+        )
+    }
+
+    #[test]
+    fn replace_then_some_with_then() {
+        check_assist(
+            replace_with_lazy_method,
+            r#"
+//- minicore: option, fn, bool_impl
+fn foo() {
+    let foo = true;
+    let x = foo.then_some$0(2);
+}
+"#,
+            r#"
+fn foo() {
+    let foo = true;
+    let x = foo.then(|| 2);
+}
+"#,
+        )
+    }
+
+    #[test]
+    fn replace_then_with_then_some() {
+        check_assist(
+            replace_with_eager_method,
+            r#"
+//- minicore: option, fn, bool_impl
+fn foo() {
+    let foo = true;
+    let x = foo.then$0(|| 2);
+}
+"#,
+            r#"
+fn foo() {
+    let foo = true;
+    let x = foo.then_some(2);
+}
 "#,
         )
     }

crates/test-utils/src/minicore.rs

@@ -1954,6 +1954,10 @@ pub mod num {
 // region:bool_impl
 #[lang = "bool"]
 impl bool {
+    pub fn then_some<T>(self, t: T) -> Option<T> {
+        if self { Some(t) } else { None }
+    }
+
     pub fn then<T, F: FnOnce() -> T>(self, f: F) -> Option<T> {
         if self { Some(f()) } else { None }
     }