1 files changed, 59 insertions, 0 deletions
diff --git a/dom/webgpu/tests/cts/checkout/src/common/util/types.ts b/dom/webgpu/tests/cts/checkout/src/common/util/types.ts
new file mode 100644
index 0000000000..dfd5e4b5ea
--- /dev/null
+++ b/dom/webgpu/tests/cts/checkout/src/common/util/types.ts
@@ -0,0 +1,59 @@
+/** Forces a type to resolve its type definitions, to make it readable/debuggable. */
+export type ResolveType<T> = T extends object
+  ? T extends infer O
+    ? { [K in keyof O]: ResolveType<O[K]> }
+    : never
+  : T;
+
+/** Returns the type `true` iff X and Y are exactly equal */
+export type TypeEqual<X, Y> = (<T>() => T extends X ? 1 : 2) extends <T>() => T extends Y ? 1 : 2
+  ? true
+  : false;
+
+/* eslint-disable-next-line @typescript-eslint/no-unused-vars */
+export function assertTypeTrue<T extends true>() {}
+
+/**
+ * Computes the intersection of a set of types, given the union of those types.
+ *
+ * From: https://stackoverflow.com/a/56375136
+ */
+export type UnionToIntersection<U> =
+  /* eslint-disable-next-line @typescript-eslint/no-explicit-any */
+  (U extends any ? (k: U) => void : never) extends (k: infer I) => void ? I : never;
+
+/** "Type asserts" that `X` is a subtype of `Y`. */
+type EnsureSubtype<X, Y> = X extends Y ? X : never;
+
+type TupleHeadOr<T, Default> = T extends readonly [infer H, ...(readonly unknown[])] ? H : Default;
+type TupleTailOr<T, Default> = T extends readonly [unknown, ...infer Tail] ? Tail : Default;
+type TypeOr<T, Default> = T extends undefined ? Default : T;
+
+/**
+ * Zips a key tuple type and a value tuple type together into an object.
+ *
+ * @template Keys Keys of the resulting object.
+ * @template Values Values of the resulting object. If a key corresponds to a `Values` member that
+ *   is undefined or past the end, it defaults to the corresponding `Defaults` member.
+ * @template Defaults Default values. If a key corresponds to a `Defaults` member that is past the
+ *   end, the default falls back to `undefined`.
+ */
+export type ZipKeysWithValues<
+  Keys extends readonly string[],
+  Values extends readonly unknown[],
+  Defaults extends readonly unknown[]
+> =
+  //
+  Keys extends readonly [infer KHead, ...infer KTail]
+    ? {
+        readonly [k in EnsureSubtype<KHead, string>]: TypeOr<
+          TupleHeadOr<Values, undefined>,
+          TupleHeadOr<Defaults, undefined>
+        >;
+      } &
+        ZipKeysWithValues<
+          EnsureSubtype<KTail, readonly string[]>,
+          TupleTailOr<Values, []>,
+          TupleTailOr<Defaults, []>
+        >
+    : {}; // K exhausted