Merge 55078b6 into d057e1d

i18next · May 14, 2024 · 74255b2 · 74255b2
2 parents d057e1d + 55078b6
commit 74255b2
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Showing 2 changed files with 76 additions and 11 deletions.
diff --git a/test/typescript/custom-types/t.test.ts b/test/typescript/custom-types/t.test.ts
@@ -156,11 +156,22 @@ describe('t', () => {
 
     it('should accept a default context key as a valid `t` function key', () => {
       expectTypeOf(t('beverage')).toMatchTypeOf('cold water');
+
+      expectTypeOf(t('beverage', { context: undefined })).toMatchTypeOf('cold water');
     });
 
     it('should throw error when no `context` is provided using and the context key has no default value ', () => {
       // @ts-expect-error dessert has no default value, it needs a context
       expectTypeOf(t('dessert')).toMatchTypeOf('error');
+
+      // @ts-expect-error dessert has no default value, it needs a context
+      expectTypeOf(t('dessert', { context: undefined })).toMatchTypeOf('error');
+
+      // TODO: edge case which is not correctly detected currently
+      // expectTypeOf(
+      //   // @ts-expect-error no default context so it must give a type error
+      //   t('dessert', { context: undefined as 'cake' | undefined }),
+      // ).toMatchTypeOf<never>();
     });
 
     it('should work with enum as a context value', () => {
@@ -174,18 +185,50 @@ describe('t', () => {
       expectTypeOf(t('dessert', { context: ctx })).toMatchTypeOf<string>();
     });
 
-    it('should trow error with string union with missing context value', () => {
+    it('should throw error with string union with missing context value', () => {
       enum DessertMissingValue {
-        COOKIE = 'cookie',
         CAKE = 'cake',
         MUFFIN = 'muffin',
         ANOTHER = 'another',
       }
 
-      const ctxMissingValue = DessertMissingValue.ANOTHER;
+      const getRandomDessert = (): DessertMissingValue =>
+        Math.random() < 0.5 ? DessertMissingValue.CAKE : DessertMissingValue.ANOTHER;
+
+      const ctxRandomValue: DessertMissingValue = getRandomDessert();
 
       // @ts-expect-error Dessert.ANOTHER is not mapped so it must give a type error
-      expectTypeOf(t('dessert', { context: ctxMissingValue })).toMatchTypeOf<string>();
+      expectTypeOf(t('dessert', { context: ctxRandomValue })).toMatchTypeOf<string>();
+
+      // @ts-expect-error Dessert.ANOTHER is not mapped so it must give a type error
+      expectTypeOf(t('dessert', { context: DessertMissingValue.ANOTHER })).toMatchTypeOf<string>();
+
+      expectTypeOf(
+        // @ts-expect-error 'another' is not mapped so it must give a type error
+        t('dessert', { context: 'cake' as 'cake' | 'another' }),
+      ).toEqualTypeOf<'a nice cake'>();
+    });
+
+    it('should not throw error with string union with undefined context value if it has a default context', () => {
+      enum BeverageValue {
+        BEER = 'beer',
+        WATER = 'water',
+      }
+
+      const getRandomBeverage = (): BeverageValue | undefined =>
+        Math.random() < 0.5 ? BeverageValue.BEER : undefined;
+
+      const ctxRandomValue = getRandomBeverage();
+
+      expectTypeOf(
+        t('beverage', { context: ctxRandomValue }),
+      ).toMatchTypeOf<'a classic beverage'>();
+
+      expectTypeOf(
+        t('beverage', { context: 'beer' as 'beer' | 'water' | undefined }),
+      ).toEqualTypeOf<'a classic beverage'>();
+
+      expectTypeOf(t('beverage', { context: undefined })).toEqualTypeOf<'a classic beverage'>();
     });
 
     it('should work with string union as a context value', () => {
@@ -195,12 +238,12 @@ describe('t', () => {
     });
 
     // @see https://github.com/i18next/i18next/issues/2172
-    // it('should trow error with string union with missing context value', () => {
-    //   expectTypeOf(
-    //     // @ts-expect-error
-    //     t('dessert', { context: 'muffin' as 'muffin' | 'cake' | 'pippo' }),
-    //   ).toMatchTypeOf<string>();
-    // });
+    it('should throw error with string union with missing context value', () => {
+      expectTypeOf(
+        // @ts-expect-error
+        t('dessert', { context: 'muffin' as 'muffin' | 'cake' | 'pippo' }),
+      ).toMatchTypeOf<string>();
+    });
   });
 
   describe('context + explicit namespace', () => {

diff --git a/typescript/t.d.ts b/typescript/t.d.ts
@@ -205,6 +205,23 @@ export type KeyWithContext<Key, TOpt extends TOptions> = TOpt['context'] extends
   ? `${Key & string}${_ContextSeparator}${TOpt['context']}`
   : Key;
 
+type ContextOfKey<
+  Ns extends Namespace,
+  Key,
+  TOpt extends TOptions,
+  Keys extends $Dictionary = KeysByTOptions<TOpt>,
+  ActualNS extends Namespace = NsByTOptions<Ns, TOpt>,
+  ActualKeys = Keys[$FirstNamespace<ActualNS>],
+> = $IsResourcesDefined extends true
+  ? Key extends `${infer Nsp}${_NsSeparator}${infer RestKey}`
+    ? Nsp extends Namespace
+      ? ContextOfKey<Nsp, RestKey, TOpt>
+      : never
+    : ActualKeys extends `${Key extends string ? Key : never}${_ContextSeparator}${infer Context}`
+    ? Context
+    : never
+  : string;
+
 export type TFunctionReturn<
   Ns extends Namespace,
   Key,
@@ -264,7 +281,12 @@ export interface TFunction<Ns extends Namespace = DefaultNamespace, KPrefix = un
     const ActualOptions extends TOpt & InterpolationMap<Ret> = TOpt & InterpolationMap<Ret>,
   >(
     ...args:
-      | [key: Key | Key[], options?: ActualOptions]
+      | [
+          key: Key | Key[],
+          options?: Omit<ActualOptions, 'context'> & {
+            context?: ContextOfKey<Ns, Key, TOpt>;
+          },
+        ]
       | [key: string | string[], options: TOpt & $Dictionary & { defaultValue: string }]
       | [key: string | string[], defaultValue: string, options?: TOpt & $Dictionary]
   ): TFunctionReturnOptionalDetails<Ret, TOpt>;