feat(question): add #30655 - string enum to union

type-challenges · Nov 3, 2023 · 0399690 · 0399690
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diff --git a/questions/30655-medium-string-enum-to-union/README.md b/questions/30655-medium-string-enum-to-union/README.md
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+Transform a string enum to union type.
+
+Example:
+```ts
+enum A {
+ a = 'aa',
+ b = 'bb',
+ c = 'cc'
+}
+
+type Result = EnumToUnion<A>; // expected to be "aa" | "bb" | "cc"
+```
diff --git a/questions/30655-medium-string-enum-to-union/info.yml b/questions/30655-medium-string-enum-to-union/info.yml
@@ -0,0 +1,7 @@
+difficulty: medium
+title: string enum to union
+tags: union, enum, string
+author:
+ github: lovetingyuan
+ name: tingyuan
+
diff --git a/questions/30655-medium-string-enum-to-union/template.ts b/questions/30655-medium-string-enum-to-union/template.ts
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+enum YourEnum {}
+type EnumToUnion = any; // write your anwser here.
+type UnionType = EnumToUnion<YourEnum>; // should be a string union.
diff --git a/questions/30655-medium-string-enum-to-union/test-cases.ts b/questions/30655-medium-string-enum-to-union/test-cases.ts
@@ -0,0 +1,23 @@
+import type { Equal, Expect } from '@type-challenges/utils'
+import { ExpectFalse, NotEqual } from '@type-challenges/utils'
+
+enum A {
+ a = 'aa',
+ b = 'bb',
+ c = 'cc'
+}
+
+enum B {
+ a = 'aa',
+}
+
+enum C {
+ a, b
+}
+
+type cases = [
+ Expect<Equal<EnumToUnion<A>, 'aa' | 'bb' | 'cc'>>,
+ Expect<Equal<EnumToUnion<B>, 'aa'>>,
+ // @ts-expect-error
+ EnumToUnion<C>,
+]