Fix nullable + enum (#1644)

Author: drwpow

packages/openapi-typescript/examples/github-api-export-type-immutable.ts

@@ -114,7 +114,11 @@ export function transformSchemaObjectWithComposition(
       options.ctx.injectFooter.push(enumType);
       return ts.factory.createTypeReferenceNode(enumType.name);
     }
-    return tsUnion(schemaObject.enum.map(tsLiteral));
+    const enumType = schemaObject.enum.map(tsLiteral);
+    if ((Array.isArray(schemaObject.type) && schemaObject.type.includes("null")) || schemaObject.nullable) {
+      enumType.push(NULL);
+    }
+    return tsUnion(enumType);
   }
 
   /**

packages/openapi-typescript/examples/github-api-immutable.ts

@@ -38,7 +38,7 @@ describe("composition", () => {
           type: ["string", "null"],
           enum: ["blue", "green", "yellow"],
         },
-        want: '"blue" | "green" | "yellow"',
+        want: '"blue" | "green" | "yellow" | null',
         // options: DEFAULT_OPTIONS,
       },
     ],
@@ -49,7 +49,7 @@ describe("composition", () => {
           type: ["string", "null"],
           enum: ["", "blue", "green", "yellow"],
         },
-        want: '"" | "blue" | "green" | "yellow"',
+        want: '"" | "blue" | "green" | "yellow" | null',
         // options: DEFAULT_OPTIONS,
       },
     ],

packages/openapi-typescript/examples/github-api.ts

@@ -77,6 +77,20 @@ describe("transformSchemaObject > string", () => {
         // options: DEFAULT_OPTIONS,
       },
     ],
+    [
+      "enum + nullable",
+      {
+        given: { type: ["string", "null"], enum: ["A", "B", "C"] },
+        want: '"A" | "B" | "C" | null',
+      },
+    ],
+    [
+      "enum + nullable (deprecated syntax)",
+      {
+        given: { type: "string", enum: ["A", "B", "C"], nullable: true },
+        want: '"A" | "B" | "C" | null',
+      },
+    ],
   ];
 
   for (const [testName, { given, want, options = DEFAULT_OPTIONS, ci }] of tests) {