From e08a36bf180ca8646473748ade3b12c212ec847a Mon Sep 17 00:00:00 2001
From: sosukesuzuki <aosukeke@gmail.com>
Date: Thu, 12 Nov 2020 17:07:36 +0900
Subject: [PATCH] Set default value to asserts property of TsTypePredicate node

---
 packages/babel-parser/src/plugins/typescript/index.js       | 1 +
 packages/babel-parser/src/types.js                          | 2 +-
 .../fixtures/typescript/class/predicate-types/output.json   | 6 ++++--
 3 files changed, 6 insertions(+), 3 deletions(-)

diff --git a/packages/babel-parser/src/plugins/typescript/index.js b/packages/babel-parser/src/plugins/typescript/index.js
index 3717fa09af8a..bde1d3d19992 100644
--- a/packages/babel-parser/src/plugins/typescript/index.js
+++ b/packages/babel-parser/src/plugins/typescript/index.js
@@ -357,6 +357,7 @@ export default (superClass: Class<Parser>): Class<Parser> =>
       const node: N.TsTypePredicate = this.startNodeAtNode(lhs);
       node.parameterName = lhs;
       node.typeAnnotation = this.tsParseTypeAnnotation(/* eatColon */ false);
+      node.asserts = false;
       return this.finishNode(node, "TSTypePredicate");
     }
 
diff --git a/packages/babel-parser/src/types.js b/packages/babel-parser/src/types.js
index 0587b30afe82..d5a28729d41b 100644
--- a/packages/babel-parser/src/types.js
+++ b/packages/babel-parser/src/types.js
@@ -1262,7 +1262,7 @@ export type TsTypePredicate = TsTypeBase & {
   type: "TSTypePredicate",
   parameterName: Identifier | TsThisType,
   typeAnnotation: TsTypeAnnotation,
-  asserts?: boolean,
+  asserts: boolean,
 };
 
 // `typeof` operator
diff --git a/packages/babel-parser/test/fixtures/typescript/class/predicate-types/output.json b/packages/babel-parser/test/fixtures/typescript/class/predicate-types/output.json
index 22a3ca661e86..e8045b7a6708 100644
--- a/packages/babel-parser/test/fixtures/typescript/class/predicate-types/output.json
+++ b/packages/babel-parser/test/fixtures/typescript/class/predicate-types/output.json
@@ -52,7 +52,8 @@
                       "type": "TSStringKeyword",
                       "start":31,"end":37,"loc":{"start":{"line":2,"column":19},"end":{"line":2,"column":25}}
                     }
-                  }
+                  },
+                  "asserts": false
                 }
               },
               "body": {
@@ -92,7 +93,8 @@
                         "type": "TSStringKeyword",
                         "start":66,"end":72,"loc":{"start":{"line":4,"column":22},"end":{"line":4,"column":28}}
                       }
-                    }
+                    },
+                    "asserts": false
                   }
                 },
                 "id": null,