Seeded mock and assert with return (#32)

.changeset/grumpy-ants-know.md

@@ -0,0 +1,5 @@
+---
+"@nrfcloud/ts-json-schema-transformer": minor
+---
+
+seeded mock

README.md

@@ -141,15 +141,20 @@ Generates an AJV validator function for the given type.
 The generic type parameter is the type you want to generate a validator for, and the single input to the function.
 This function call is replaced by the generated validator at compile time.
 
-#### `getMockObject<T>(): T`
+#### `getMockObject<T, Seed>(): T`
 
 Generate a mock object for the given type.
 Should support all formats as well as other constraints.
+You can optionally specify a seed for the random number generator as the second parameter.
 
 #### `assertValid<T>(obj: unknown): asserts obj is T`
 
 Validates that a given object satisfies the constraints defined in the given generic type parameter's schema. The method will throw an error if validation fails. This function call is replaced a wrapped validator method at compile time.
 
+#### `assert<T>(obj: unknown): T`
+
+Very similar to `assertValid` but returns the passed object instead of narrowing the type.
+
 ### JSDoc Tags
 
 You can add JSDoc tags to your interfaces and types to add additional schema information.
@@ -394,6 +399,10 @@ Note that not all options are exposed, though more could be added in the future.
 
         // Whether properties should be sorted (stable)
         "sortProps": true,
+
+        // Explicitly set the seed used for mock data generation.
+        // You can disable seeding by setting this false
+        "seed": "this is a seed"
       }
     ]
   }

package.json

@@ -62,6 +62,7 @@
     "@types/jest": "^29.5.11",
     "@types/json-schema": "^7.0.15",
     "@types/node": "^18.19.3",
+    "@types/seedrandom": "^3.0.8",
     "dprint": "^0.35.4",
     "husky": "^8.0.3",
     "jest": "^29.7.0",
@@ -84,7 +85,8 @@
     "@apidevtools/json-schema-ref-parser": "^11.7.0",
     "ajv": "^8.12.0",
     "esbuild": "^0.23.0",
-    "json-schema-faker": "npm:@jfconley/json-schema-faker@0.5.0-rcv.48",
+    "json-schema-faker": "^0.5.6",
+    "seedrandom": "^3.0.5",
     "ts-json-schema-generator": "^2.4.0-next.2"
   }
 }

src/index.ts

@@ -20,7 +20,7 @@ export function getValidator<T>(): ValidateFunction<T> {
  * Get a mock object for the provided type
  * @transformer ts-json-schema-transformer
  */
-export function getMockObject<T>(): T {
+export function getMockObject<T, const S extends string = "none">(): IfEquals<S, string, never, T> {
   throw new Error("Not implemented. Did you forget to run the transformer?");
 }
 
@@ -32,6 +32,14 @@ export function assertValid<T = never, U extends T = T>(_obj: unknown): asserts
   throw new Error("Not implemented. Did you forget to run the transformer?");
 }
 
+/**
+ * Assert that an object is valid and returns the object back
+ * @transformer ts-json-schema-transformer
+ */
+export function assert<T = never, U extends T = T>(_obj: unknown): U {
+  throw new Error("Not implemented. Did you forget to run the transformer?");
+}
+
 export class ValidationError extends Error {
 }
 
@@ -46,3 +54,8 @@ export function validationAssertion(validator: ValidateFunction<unknown>, obj: u
   }
   return obj;
 }
+
+type Exact<T, U> = IfEquals<T, U, T, never>;
+type IfEquals<T, U, Y = unknown, N = never> = (<G>() => G extends T ? 1 : 2) extends (<G>() => G extends U ? 1 : 2) ? Y
+  : N;
+type NotAny<T> = 0 extends (1 & T) ? never : T;

src/project.ts

@@ -7,6 +7,9 @@ export interface IProject {
   options: {
     schema: SchemaConfig;
     validation: AJVOptions;
+    mock: {
+      seed: string | false;
+    };
   };
   checker: ts.TypeChecker;
   schemaGenerator: SchemaGenerator;
@@ -23,6 +26,8 @@ export type SchemaConfig = Pick<
   "sortProps" | "expose" | "jsDoc" | "strictTuples" | "encodeRefs" | "additionalProperties"
 >;
 
+export const DEFAULT_SEED = "emerson";
+
 export const AJV_DEFAULTS = {
   useDefaults: true,
   coerceTypes: false,
@@ -48,4 +53,6 @@ export const SCHEMA_DEFAULTS = {
   functions: "fail",
 } as const satisfies Config;
 
-export type IOptions = AJVOptions & SchemaConfig;
+export type IOptions = AJVOptions & SchemaConfig & {
+  seed?: string | false;
+};