fix: correctly generate anyOf on unions with string and boolean constant

Author: pixunil

src/TypeFormatter/LiteralUnionTypeFormatter.ts

@@ -55,12 +55,18 @@ export class LiteralUnionTypeFormatter implements SubTypeFormatter {
             appendTypeValues(type, typeValues);
         }
 
-        const schema = {
-            type: toEnumType(Array.from(typeNames)),
-            enum: Array.from(typeValues),
-        };
-
-        return preserveLiterals ? { anyOf: [{ type: "string" }, schema] } : schema;
+        const schema =
+            typeNames.size === 1 && typeValues.size === 1
+                ? {
+                      type: toEnumType(Array.from(typeNames)),
+                      const: Array.from(typeValues)[0],
+                  }
+                : {
+                      type: toEnumType(Array.from(typeNames)),
+                      enum: Array.from(typeValues),
+                  };
+
+        return hasString ? { anyOf: [{ type: "string" }, schema] } : schema;
     }
 
     public getChildren(): BaseType[] {

test/valid-data/type-union/main.ts

@@ -6,6 +6,9 @@ type MyType4 = "s" | 1;
 type MyType5 = "s" | 1[];
 type MyType6 = ("s" | 1)[];
 
+type MyType7 = string | true;
+type MyType8 = "s" | true;
+
 export interface TypeUnion {
     var1: MyType1;
     var2: MyType2;
@@ -14,4 +17,7 @@ export interface TypeUnion {
     var4: MyType4;
     var5: MyType5;
     var6: MyType6;
+
+    var7: MyType7;
+    var8: MyType8;
 }

test/valid-data/type-union/schema.json

@@ -70,6 +70,27 @@
             ]
           },
           "type": "array"
+        },
+        "var7": {
+          "anyOf": [
+            {
+              "type": "string"
+            },
+            {
+              "const": true,
+              "type": "boolean"
+            }
+          ]
+        },
+        "var8": {
+          "enum": [
+            "s",
+            true
+          ],
+          "type": [
+            "string",
+            "boolean"
+          ]
         }
       },
       "required": [
@@ -78,7 +99,9 @@
         "var3",
         "var4",
         "var5",
-        "var6"
+        "var6",
+        "var7",
+        "var8"
       ],
       "type": "object"
     }