1 files changed, 124 insertions, 0 deletions
diff --git a/dom/webgpu/tests/cts/checkout/src/common/internal/params_utils.ts b/dom/webgpu/tests/cts/checkout/src/common/internal/params_utils.ts
new file mode 100644
index 0000000000..07d2f836f1
--- /dev/null
+++ b/dom/webgpu/tests/cts/checkout/src/common/internal/params_utils.ts
@@ -0,0 +1,124 @@
+import { TestParams } from '../framework/fixture.js';
+import { ResolveType, UnionToIntersection } from '../util/types.js';
+import { assert } from '../util/util.js';
+
+import { comparePublicParamsPaths, Ordering } from './query/compare.js';
+import { kWildcard, kParamSeparator, kParamKVSeparator } from './query/separators.js';
+
+export type JSONWithUndefined =
+  | undefined
+  | null
+  | number
+  | string
+  | boolean
+  | readonly JSONWithUndefined[]
+  // Ideally this would recurse into JSONWithUndefined, but it breaks code.
+  | { readonly [k: string]: unknown };
+export interface TestParamsRW {
+  [k: string]: JSONWithUndefined;
+}
+export type TestParamsIterable = Iterable<TestParams>;
+
+export function paramKeyIsPublic(key: string): boolean {
+  return !key.startsWith('_');
+}
+
+export function extractPublicParams(params: TestParams): TestParams {
+  const publicParams: TestParamsRW = {};
+  for (const k of Object.keys(params)) {
+    if (paramKeyIsPublic(k)) {
+      publicParams[k] = params[k];
+    }
+  }
+  return publicParams;
+}
+
+export const badParamValueChars = new RegExp(
+  '[' + kParamKVSeparator + kParamSeparator + kWildcard + ']'
+);
+
+export function publicParamsEquals(x: TestParams, y: TestParams): boolean {
+  return comparePublicParamsPaths(x, y) === Ordering.Equal;
+}
+
+export type KeyOfNeverable<T> = T extends never ? never : keyof T;
+export type AllKeysFromUnion<T> = keyof T | KeyOfNeverable<UnionToIntersection<T>>;
+export type KeyOfOr<T, K, Default> = K extends keyof T ? T[K] : Default;
+
+/**
+ * Flatten a union of interfaces into a single interface encoding the same type.
+ *
+ * Flattens a union in such a way that:
+ * `{ a: number, b?: undefined } | { b: string, a?: undefined }`
+ * (which is the value type of `[{ a: 1 }, { b: 1 }]`)
+ * becomes `{ a: number | undefined, b: string | undefined }`.
+ *
+ * And also works for `{ a: number } | { b: string }` which maps to the same.
+ */
+export type FlattenUnionOfInterfaces<T> = {
+  [K in AllKeysFromUnion<T>]: KeyOfOr<
+    T,
+    // If T always has K, just take T[K] (union of C[K] for each component C of T):
+    K,
+    // Otherwise, take the union of C[K] for each component C of T, PLUS undefined:
+    undefined | KeyOfOr<UnionToIntersection<T>, K, void>
+  >;
+};
+
+/* eslint-disable-next-line @typescript-eslint/no-unused-vars */
+function typeAssert<T extends 'pass'>() {}
+{
+  type Test<T, U> = [T] extends [U]
+    ? [U] extends [T]
+      ? 'pass'
+      : { actual: ResolveType<T>; expected: U }
+    : { actual: ResolveType<T>; expected: U };
+
+  type T01 = { a: number } | { b: string };
+  type T02 = { a: number } | { b?: string };
+  type T03 = { a: number } | { a?: number };
+  type T04 = { a: number } | { a: string };
+  type T05 = { a: number } | { a?: string };
+
+  type T11 = { a: number; b?: undefined } | { a?: undefined; b: string };
+
+  type T21 = { a: number; b?: undefined } | { b: string };
+  type T22 = { a: number; b?: undefined } | { b?: string };
+  type T23 = { a: number; b?: undefined } | { a?: number };
+  type T24 = { a: number; b?: undefined } | { a: string };
+  type T25 = { a: number; b?: undefined } | { a?: string };
+  type T26 = { a: number; b?: undefined } | { a: undefined };
+  type T27 = { a: number; b?: undefined } | { a: undefined; b: undefined };
+
+  /* prettier-ignore */ {
+    typeAssert<Test<FlattenUnionOfInterfaces<T01>, { a: number | undefined; b: string | undefined }>>();
+    typeAssert<Test<FlattenUnionOfInterfaces<T02>, { a: number | undefined; b: string | undefined }>>();
+    typeAssert<Test<FlattenUnionOfInterfaces<T03>, { a: number | undefined }>>();
+    typeAssert<Test<FlattenUnionOfInterfaces<T04>, { a: number | string }>>();
+    typeAssert<Test<FlattenUnionOfInterfaces<T05>, { a: number | string | undefined }>>();
+
+    typeAssert<Test<FlattenUnionOfInterfaces<T11>, { a: number | undefined; b: string | undefined }>>();
+
+    typeAssert<Test<FlattenUnionOfInterfaces<T22>, { a: number | undefined; b: string | undefined }>>();
+    typeAssert<Test<FlattenUnionOfInterfaces<T23>, { a: number | undefined; b: undefined }>>();
+    typeAssert<Test<FlattenUnionOfInterfaces<T24>, { a: number | string; b: undefined }>>();
+    typeAssert<Test<FlattenUnionOfInterfaces<T25>, { a: number | string | undefined; b: undefined }>>();
+    typeAssert<Test<FlattenUnionOfInterfaces<T27>, { a: number | undefined; b: undefined }>>();
+
+    // Unexpected test results - hopefully okay to ignore these
+    typeAssert<Test<FlattenUnionOfInterfaces<T21>, { b: string | undefined }>>();
+    typeAssert<Test<FlattenUnionOfInterfaces<T26>, { a: number | undefined }>>();
+  }
+}
+
+export type Merged<A, B> = MergedFromFlat<A, FlattenUnionOfInterfaces<B>>;
+export type MergedFromFlat<A, B> = {
+  [K in keyof A | keyof B]: K extends keyof B ? B[K] : K extends keyof A ? A[K] : never;
+};
+
+export function mergeParams<A extends {}, B extends {}>(a: A, b: B): Merged<A, B> {
+  for (const key of Object.keys(a)) {
+    assert(!(key in b), 'Duplicate key: ' + key);
+  }
+  return { ...a, ...b } as Merged<A, B>;
+}