fix(lsp): ensure insert_text is passed back on completions (#9951)

Fixes #9920

cli/lsp/language_server.rs

@@ -3025,6 +3025,68 @@ mod tests {
     harness.run().await;
   }
 
+  #[tokio::test]
+  async fn test_completions_optional() {
+    let mut harness = LspTestHarness::new(vec![
+      ("initialize_request.json", LspResponse::RequestAny),
+      ("initialized_notification.json", LspResponse::None),
+      (
+        "did_open_notification_completion_optional.json",
+        LspResponse::None,
+      ),
+      (
+        "completion_request_optional.json",
+        LspResponse::Request(
+          2,
+          json!({
+            "isIncomplete": false,
+            "items": [
+              {
+                "label": "b?",
+                "kind": 5,
+                "sortText": "1",
+                "filterText": "b",
+                "insertText": "b",
+                "data": {
+                  "tsc": {
+                    "specifier": "file:///a/file.ts",
+                    "position": 79,
+                    "name": "b",
+                    "useCodeSnippet": false
+                  }
+                }
+              }
+            ]
+          }),
+        ),
+      ),
+      (
+        "completion_resolve_request_optional.json",
+        LspResponse::Request(
+          4,
+          json!({
+            "label": "b?",
+            "kind": 5,
+            "detail": "(property) A.b?: string | undefined",
+            "documentation": {
+              "kind": "markdown",
+              "value": ""
+            },
+            "sortText": "1",
+            "filterText": "b",
+            "insertText": "b"
+          }),
+        ),
+      ),
+      (
+        "shutdown_request.json",
+        LspResponse::Request(3, json!(null)),
+      ),
+      ("exit_notification.json", LspResponse::None),
+    ]);
+    harness.run().await;
+  }
+
   #[derive(Deserialize)]
   struct PerformanceAverages {
     averages: Vec<PerformanceAverage>,

cli/lsp/tsc.rs

@@ -1188,10 +1188,10 @@ impl CompletionEntry {
     }
 
     let text_edit =
-      if let (Some(text_span), Some(new_text)) = (range, insert_text) {
+      if let (Some(text_span), Some(new_text)) = (range, &insert_text) {
         let range = text_span.to_range(line_index);
         let insert_replace_edit = lsp::InsertReplaceEdit {
-          new_text,
+          new_text: new_text.clone(),
           insert: range,
           replace: range,
         };
@@ -1216,6 +1216,7 @@ impl CompletionEntry {
       preselect,
       text_edit,
       filter_text,
+      insert_text,
       detail,
       tags,
       data: Some(json!({

cli/tests/lsp/completion_request_optional.json

@@ -0,0 +1,18 @@
+{
+  "jsonrpc": "2.0",
+  "id": 2,
+  "method": "textDocument/completion",
+  "params": {
+    "textDocument": {
+      "uri": "file:///a/file.ts"
+    },
+    "position": {
+      "line": 8,
+      "character": 4
+    },
+    "context": {
+      "triggerKind": 2,
+      "triggerCharacter": "."
+    }
+  }
+}

cli/tests/lsp/completion_resolve_request_optional.json

@@ -0,0 +1,20 @@
+{
+  "jsonrpc": "2.0",
+  "id": 4,
+  "method": "completionItem/resolve",
+  "params": {
+    "label": "b?",
+    "kind": 5,
+    "sortText": "1",
+    "filterText": "b",
+    "insertText": "b",
+    "data": {
+      "tsc": {
+        "specifier": "file:///a/file.ts",
+        "position": 79,
+        "name": "b",
+        "useCodeSnippet": false
+      }
+    }
+  }
+}

cli/tests/lsp/did_open_notification_completion_optional.json

@@ -0,0 +1,12 @@
+{
+  "jsonrpc": "2.0",
+  "method": "textDocument/didOpen",
+  "params": {
+    "textDocument": {
+      "uri": "file:///a/file.ts",
+      "languageId": "typescript",
+      "version": 1,
+      "text": "interface A {\n  b?: string;\n}\n\nconst o: A = {};\n\nfunction c(s: string) {}\n\nc(o.)"
+    }
+  }
+}