Make enum mocking deterministic

CruGlobal · Oct 30, 2024 · 7cb19b0 · 7cb19b0
1 parent 785b8b0
commit 7cb19b0
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Showing 4 changed files with 12 additions and 8 deletions.
diff --git a/src/__tests__/lib.test.ts b/src/__tests__/lib.test.ts
@@ -3,6 +3,8 @@ import { GraphQLError } from "graphql";
 import schema from "./schema";
 import schemaAST from "./schema-ast.json";
 
+const seed = 'seed';
+
 describe("Automocking", () => {
   describe("Guardrails", () => {
     test("it throws without a valid schema", () => {
@@ -89,10 +91,15 @@ describe("Automocking", () => {
           returnEnum
         }
       `;
-      const resp: any = ergonomock(schema, testQuery);
+      const resp: any = ergonomock(schema, testQuery, { seed });
       expect(resp.data).toMatchObject({
         returnEnum: expect.toBeOneOf(["A", "B", "C"]),
       });
+
+      for (let i = 0; i < 10; ++i) {
+        const resp2 = ergonomock(schema, testQuery, { seed });
+        expect(resp).toEqual(resp2);
+      }
     });
 
     test("can automock unions", () => {

diff --git a/src/mock.ts b/src/mock.ts
@@ -19,7 +19,6 @@ import {
   buildASTSchema,
 } from "graphql";
 import random from "./utils/random";
-import getRandomElement from "./utils/getRandomElement";
 import forEachFieldInQuery from "./utils/forEachFieldInQuery";
 
 const defaultMockMap: Map<string, GraphQLFieldResolver<any, any>> = new Map();
@@ -117,7 +116,7 @@ export function ergonomock(
       if (fieldType instanceof GraphQLUnionType || fieldType instanceof GraphQLInterfaceType) {
         let implementationType;
         const possibleTypes = schema.getPossibleTypes(fieldType);
-        implementationType = getRandomElement(possibleTypes);
+        implementationType = random.item(possibleTypes);
         return Object.assign(
           { __typename: implementationType },
           mockResolverFunction(implementationType)(root, args, context, info)
@@ -130,7 +129,7 @@ export function ergonomock(
 
       // Default mock for enums
       if (fieldType instanceof GraphQLEnumType) {
-        return getRandomElement(fieldType.getValues()).value;
+        return random.item(fieldType.getValues()).value;
       }
 
       // Automock object types

diff --git a/src/utils/getRandomElement.ts b/src/utils/getRandomElement.ts
diff --git a/src/utils/random.ts b/src/utils/random.ts
@@ -252,6 +252,8 @@ const random = {
   // max is exclusive, min is inclusive
   float: (max: number = 100, min: number = 1) => rng() * (max - min) + min,
 
+  item: <T>(array: readonly T[]): T => array[random.integer(array.length, 0)],
+
   // max and min are inclusive
   list: (maxLength: number = 4, minLength: number = 1) => [
     ...Array(random.integer(maxLength + 1, minLength))