fix: Unknown type "undefined" when using generics without base type (#1978)

Author: arthurfiorette

src/NodeParser/ArrayNodeParser.ts

@@ -1,8 +1,9 @@
 import ts from "typescript";
-import { Context, NodeParser } from "../NodeParser.js";
-import { SubNodeParser } from "../SubNodeParser.js";
+import type { Context, NodeParser } from "../NodeParser.js";
+import type { SubNodeParser } from "../SubNodeParser.js";
+import { AnyType } from "../Type/AnyType.js";
 import { ArrayType } from "../Type/ArrayType.js";
-import { BaseType } from "../Type/BaseType.js";
+import type { BaseType } from "../Type/BaseType.js";
 
 export class ArrayNodeParser implements SubNodeParser {
     public constructor(protected childNodeParser: NodeParser) {}
@@ -13,6 +14,7 @@ export class ArrayNodeParser implements SubNodeParser {
 
     public createType(node: ts.ArrayTypeNode, context: Context): BaseType {
         const type = this.childNodeParser.createType(node.elementType, context);
-        return new ArrayType(type);
+        // Generics without `extends` or `defaults` cannot be resolved, so we fallback to `any`
+        return new ArrayType(type ?? new AnyType());
     }
 }

test/valid-data-other.test.ts

@@ -78,6 +78,7 @@ describe("valid-data-other", () => {
     it("array-min-items-2", assertValidSchema("array-min-items-2", "MyType"));
     it("array-min-max-items", assertValidSchema("array-min-max-items", "MyType"));
     it("array-min-max-items-optional", assertValidSchema("array-min-max-items-optional", "MyType"));
+    it("array-function-generics", assertValidSchema("array-function-generics", "*"));
     it("array-max-items-optional", assertValidSchema("array-max-items-optional", "MyType"));
     it("shorthand-array", assertValidSchema("shorthand-array", "MyType"));
 

test/valid-data/array-function-generics/main.ts

@@ -0,0 +1,4 @@
+export function arrayGenerics<T>(a: T[], b: T[]): T[] {
+    console.log(a, b);
+    return b;
+}

test/valid-data/array-function-generics/schema.json

@@ -0,0 +1,30 @@
+{
+  "$ref": "#/definitions/arrayGenerics",
+  "$schema": "http://json-schema.org/draft-07/schema#",
+  "definitions": {
+    "arrayGenerics": {
+      "$comment": "(a: T[], b: T[]) => T[]",
+      "type": "object",
+      "properties": {
+        "namedArgs": {
+          "type": "object",
+          "properties": {
+            "a": {
+              "type": "array",
+              "items": {}
+            },
+            "b": {
+              "type": "array",
+              "items": {}
+            }
+          },
+          "required": [
+            "a",
+            "b"
+          ],
+          "additionalProperties": false
+        }
+      }
+    }
+  }
+}