add i18n compiletime checks

Author: garronej

src/lib/i18n.tsx

@@ -86,9 +86,6 @@ type NonFunctionMessageKey<FrMessages extends Record<string, string | ((params:
 type FunctionMessageKey<FrMessages extends Record<string, string | ((params: any) => string)>> =
     Exclude<keyof FrMessages, NonFunctionMessageKey<FrMessages>>;
 
-type X = NonFunctionMessageKey<{ foo: string; bar: (params: { x: number }) => string }>;
-type Y = FunctionMessageKey<{ foo: string; bar: (params: { x: number }) => string }>;
-
 export function createComponentI18nApi<
     ComponentName extends string,
     FrMessages extends Record<string, string | ((params: any) => string)>

test/types/i18n.ts

@@ -0,0 +1,29 @@
+import { createComponentI18nApi } from "../../src/lib/i18n";
+import { assert } from "tsafe/assert";
+import type { Equals } from "tsafe";
+
+const { useTranslation, addSomeDsfrComponentTranslations } = createComponentI18nApi({
+    "componentName": "SomeDsfrComponent",
+    "frMessages": {
+        /* spell-checker: disable */
+
+        "do something": ({ what }: { what: string }) => `Faire ${what}`,
+        "the good": "le bien"
+        /* spell-checker: enable */
+    }
+});
+
+addSomeDsfrComponentTranslations({
+    "lang": "en",
+    "messages": {
+        "do something": ({ what }) => {
+            assert<Equals<typeof what, string>>();
+            return `Do ${what}`;
+        },
+        "the good": "the good"
+    }
+});
+
+const { t } = useTranslation();
+
+t("do something", { "what": t("the good") });