fix(schema): infer patternProperties value type for any single pattern

packages/quicktype-core/src/input/JSONSchemaInput.ts

@@ -1139,14 +1139,22 @@ async function addTypesInSchema(
             }
 
             let additionalProperties = schema.additionalProperties;
-            // This is an incorrect hack to fix an issue with a Go->Schema generator:
+            // This is an incorrect hack to treat a single pattern property as
+            // additional properties:
             // https://github.com/quicktype/quicktype/issues/976
+            // https://github.com/quicktype/quicktype/issues/1464
             if (
                 additionalProperties === undefined &&
                 typeof schema.patternProperties === "object" &&
-                hasOwnProperty(schema.patternProperties, ".*")
+                schema.patternProperties !== null
             ) {
-                additionalProperties = schema.patternProperties[".*"];
+                const patterns = Object.getOwnPropertyNames(
+                    schema.patternProperties,
+                );
+                if (patterns.length === 1) {
+                    additionalProperties =
+                        schema.patternProperties[patterns[0]];
+                }
             }
 
             // Handle unevaluatedProperties if additionalProperties is not defined

test/inputs/schema/pattern-properties.1.fail.json

@@ -0,0 +1,3 @@
+{
+  "enabled": {}
+}

test/inputs/schema/pattern-properties.1.json

@@ -0,0 +1,3 @@
+{
+  "enabled": true
+}

test/inputs/schema/pattern-properties.schema

@@ -0,0 +1,9 @@
+{
+  "$schema": "http://json-schema.org/draft-04/schema#",
+  "type": "object",
+  "patternProperties": {
+    "^[a-zA-Z]\\w*$": {
+      "type": "boolean"
+    }
+  }
+}

test/languages.ts

@@ -56,6 +56,10 @@ const skipsUntypedUnions = [
 const skipsMapValueValidation = [
     "go-schema-pattern-properties.schema",
     "unevaluated-properties.schema",
+    // These languages deserialize a map without validating the value type
+    // (unchecked generic casts, raw map readers, or no runtime type checks),
+    // so the `{"enabled": {}}` fail sample round-trips instead of failing.
+    "pattern-properties.schema",
 ];
 
 // The generated deserializer for a top-level array of scalars uses a
@@ -263,6 +267,11 @@ export const JavaLanguage: Language = {
     skipSchema: [
         "integer-before-number.schema", // Python-specific union-order regression.
         "keyword-unions.schema", // generates classes with names that are case-insensitively equal
+        // A top-level map deserializes via a raw `Map.class` reader
+        // (javaTypeWithoutGenerics drops the value type), so map value
+        // types are not validated on parse and the fail sample does not
+        // fail. Nested typed maps are still validated elsewhere.
+        "pattern-properties.schema",
         // The generated converter deserializes a top-level array with a raw
         // `List`, so a mistyped element round-trips instead of failing.
         ...skipsArrayElementValidation,
@@ -1976,6 +1985,9 @@ export const PHPLanguage: Language = {
         "top-level-enum.schema",
         // The driver does not support top-level arrays.
         "union.schema",
+        // PHP has no type aliases, so a top-level map produces no named
+        // TopLevel class and the driver's TopLevel::from() call fails.
+        "pattern-properties.schema",
         "issue2680-top-level-array.schema",
     ],
     rendererOptions: {},