feat(macro): make select macro choices strictly typed

Author: MikaelSiidorow

packages/core/macro/__typetests__/index.test-d.tsx

@@ -266,7 +266,9 @@ expectType<string>(
 //// Select
 ///////////////////
 
-const gender = "male"
+type Gender = "male" | "female" | "other"
+const gender = "male" as Gender // make the type less specific on purpose
+
 expectType<string>(
   select(gender, {
     // todo: here is inconsistency between jsx macro and js.
@@ -280,6 +282,36 @@ expectType<string>(
   })
 )
 
+expectType<string>(
+  // @ts-expect-error: missing required property and other is not supplied
+  select(gender, {
+    male: "he",
+  })
+)
+
+expectType<string>(
+  // missing required property is okay, if other is supplied as fallback
+  select(gender, {
+    male: "he",
+    other: "they",
+  })
+)
+
+expectType<string>(
+  select(gender, {
+    // @ts-expect-error extra properties are not allowed
+    incorrect: "",
+  })
+)
+
+expectType<string>(
+  select(gender, {
+    // @ts-expect-error extra properties are not allowed even with other fallback
+    incorrect: "",
+    other: "they",
+  })
+)
+
 expectType<string>(
   // @ts-expect-error value could be strings only
   select(5, {

packages/core/macro/index.d.ts

@@ -154,12 +154,21 @@ export function selectOrdinal(
   options: ChoiceOptions
 ): string
 
-type SelectOptions = {
+type SelectOptionsExhaustive<T extends string = string> = {
+  [key in T]: string
+}
+
+type SelectOptionsNonExhaustive<T extends string = string> = {
   /** Catch-all option */
   other: string
-  [matches: string]: string
+} & {
+  [key in T]?: string
 }
 
+type SelectOptions<T extends string = string> =
+  | SelectOptionsExhaustive<T>
+  | SelectOptionsNonExhaustive<T>
+
 /**
  * Selects a translation based on a value
  *
@@ -180,9 +189,9 @@ type SelectOptions = {
  * @param value The key of choices to use
  * @param choices
  */
-export function select(
-  value: string | LabeledExpression<string>,
-  choices: SelectOptions
+export function select<T extends string = string>(
+  value: T | LabeledExpression<T>,
+  choices: SelectOptions<T>
 ): string
 
 /**