Fix completion record for variable declarations (babel#13596)

packages/babel-traverse/src/path/family.ts

@@ -193,11 +193,19 @@ function getStatementListCompletion(
     }
   } else if (paths.length) {
     // When we are in a context where `break` must not exist, we can skip linear
-    // search on statement lists and assume that the last statement determines
-    // the completion
-    completions = completions.concat(
-      _getCompletionRecords(paths[paths.length - 1], context),
-    );
+    // search on statement lists and assume that the last
+    // non-variable-declaration statement determines the completion.
+    for (let i = paths.length - 1; i >= 0; i--) {
+      const pathCompletions = _getCompletionRecords(paths[i], context);
+      if (
+        pathCompletions.length > 1 ||
+        (pathCompletions.length === 1 &&
+          !pathCompletions[0].path.isVariableDeclaration())
+      ) {
+        completions = completions.concat(pathCompletions);
+        break;
+      }
+    }
   }
   return completions;
 }

packages/babel-traverse/test/family.js

@@ -109,6 +109,44 @@ describe("path/family", function () {
       expect(consequentHasScope).toBe(true);
     });
   });
+  describe("getCompletionRecords", function () {
+    it("should skip variable declarations", function () {
+      const ast = parse("'foo' + 'bar'; var a = 10; let b = 20; const c = 30;");
+      let records = [];
+      traverse(ast, {
+        Program(path) {
+          records = path.getCompletionRecords();
+        },
+      });
+      expect(records).toHaveLength(1);
+      expect(records[0].node.type).toBe("ExpressionStatement");
+      expect(records[0].node.expression.type).toBe("BinaryExpression");
+    });
+
+    it("should skip variable declarations in a BlockStatement", function () {
+      const ast = parse("'foo' + 'bar'; { var a = 10; }");
+      let records = [];
+      traverse(ast, {
+        Program(path) {
+          records = path.getCompletionRecords();
+        },
+      });
+      expect(records).toHaveLength(1);
+      expect(records[0].node.type).toBe("ExpressionStatement");
+      expect(records[0].node.expression.type).toBe("BinaryExpression");
+    });
+
+    it("should be empty if there are only variable declarations", function () {
+      const ast = parse("var a = 10; let b = 20; const c = 30;");
+      let records = [];
+      traverse(ast, {
+        Program(path) {
+          records = path.getCompletionRecords();
+        },
+      });
+      expect(records).toHaveLength(0);
+    });
+  });
 });
 
 function hop(o, key) {