feat(typescript-types): Make Assign assignable to Generics by removing optionals

packages/typescript-types/test/assign.tst.ts

@@ -11,21 +11,21 @@ interface OptionsWithRequired {
 interface DefaultValues {
 	tag: 'Max Mustermann'
 	age: 17
-	relations: []
+	relations: Array<OptionsWithRequired>
 }
 
 expect<Assign<OptionsWithRequired, DefaultValues, { name: 'Another Name' }>>().type.toBe<{
 	name: 'Another Name'
 	tag: 'Max Mustermann'
 	age: 17
-	relations: []
+	relations: Array<OptionsWithRequired>
 }>()
 
 expect<Assign<OptionsWithRequired, DefaultValues, { name: 'Another Name'; age: 18 }>>().type.toBe<{
 	name: 'Another Name'
 	tag: 'Max Mustermann'
 	age: 18
-	relations: []
+	relations: Array<OptionsWithRequired>
 }>()
 
 interface Options {
@@ -39,8 +39,14 @@ expect<Assign<Options, DefaultValues, {}>>().type.toBe<{
 }>()
 
 interface SpecifiedOptions extends Options {}
-
 expect<Assign<Options, DefaultValues, SpecifiedOptions>>().type.toBe<{
 	tag: 'Max Mustermann'
 	age: 17
 }>()
+
+type SomethingRequiringAllOptions<Opts extends Required<Options>> = Opts
+type SomethingProvidingDefaultOptions<Opts extends Options = {}> = SomethingRequiringAllOptions<
+	Assign<Options, DefaultValues, Opts>
+>
+
+expect<SomethingProvidingDefaultOptions<{ age: 5 }>>().type.toBe<{ tag: 'Max Mustermann'; age: 5 }>()

packages/typescript-types/test/is-undefined.tst.ts

@@ -0,0 +1,11 @@
+import type { IsUndefined } from '@/is-undefined.js'
+import { expect } from 'tstyche'
+
+expect<IsUndefined<undefined>>().type.toBe<true>()
+
+expect<IsUndefined<1>>().type.toBe<false>()
+expect<IsUndefined<'somestring'>>().type.toBe<false>()
+expect<IsUndefined<null>>().type.toBe<false>()
+expect<IsUndefined<unknown>>().type.toBe<false>()
+expect<IsUndefined<any>>().type.toBe<false>()
+expect<IsUndefined<never>>().type.toBe<false>()

packages/typescript-types/test/pick-assignable.tst.ts

@@ -0,0 +1,21 @@
+import type { PickAssignable } from '@/pick-assignable.js'
+import { expect } from 'tstyche'
+
+interface Example {
+	name: string
+	age: number
+}
+
+expect<PickAssignable<Example, 'name' | 'age'>>().type.toBe<Example>()
+expect<PickAssignable<Example, any>>().type.toBe<Example>()
+
+expect<PickAssignable<Example, 'name'>>().type.toBe<{ name: string }>()
+
+expect<PickAssignable<Example, 'nonexisting'>>().type.toBe<{}>()
+expect<PickAssignable<Example, never>>().type.toBe<{}>()
+
+expect<PickAssignable<unknown, 'age'>>().type.toBe<{}>()
+expect<PickAssignable<any, 'age'>>().type.toBe<{}>()
+
+expect<PickAssignable<undefined, 'age'>>().type.toBe<{}>()
+expect<PickAssignable<never, 'age'>>().type.toBe<{}>()