Highlight binary expressions on operator hover

Return the enclosing binary expression range with operator hover responses so
editors highlight the complete operation instead of only showing hover content.

Author: Sano007

pyrefly/lib/lsp/wasm/hover.rs

@@ -1488,8 +1488,8 @@ pub fn get_hover_with_verbosity(
         return keyword_hover;
     };
 
-    // `a and b and c` is a single flat BoolOp, so hovering any operator in the
-    // chain highlights the whole expression. `not` highlights its unary expression.
+    // Operators highlight their enclosing expression. `a and b and c` is a single flat
+    // BoolOp, so hovering any operator in the chain highlights the whole expression.
     let range = ast
         .as_deref()
         .zip(module_info.as_ref())
@@ -1501,6 +1501,7 @@ pub fn get_hover_with_verbosity(
                     AnyNodeRef::ExprBoolOp(bool_op) => {
                         Some(module_info.to_lsp_range(bool_op.range()))
                     }
+                    AnyNodeRef::ExprBinOp(bin_op) => Some(module_info.to_lsp_range(bin_op.range())),
                     AnyNodeRef::ExprUnaryOp(unary_op) if unary_op.op == UnaryOp::Not => {
                         Some(module_info.to_lsp_range(unary_op.range()))
                     }

pyrefly/lib/test/lsp/hover.rs

@@ -2606,6 +2606,32 @@ y = 1 or 2
     );
 }
 
+#[test]
+fn hover_over_binary_operator_highlights_binary_expression() {
+    let code = r#"
+x = 1 | 2
+#     ^
+"#;
+    let mut test_env = TestEnv::new();
+    test_env.add("main", code);
+    let (state, handle) = test_env
+        .with_default_require_level(Require::Exports)
+        .to_state();
+    let handle = handle("main");
+    let position = extract_cursors_for_test(code)[0];
+    let range = match get_hover(&state.transaction(), &handle, position, false) {
+        Some(hover) => hover.range,
+        None => panic!("Expected hover result for binary operator"),
+    };
+    assert_eq!(
+        range,
+        Some(Range {
+            start: Position::new(1, 4),
+            end: Position::new(1, 9),
+        })
+    );
+}
+
 #[test]
 fn hover_over_not_operator_highlights_unary_expression() {
     let code = r#"