fix(types): onMutateResult is always defined in onSuccess callback (#9677)

* fix(types): onMutateResult is always defined in onSuccess callback
this is guaranteed because if onMutate fails or rejects, onSuccess is never called. if onMutate is not present, the type will be unknown
* chore: fix tests

Author: TkDodo

packages/angular-query-experimental/src/__tests__/mutation-options.test-d.ts

@@ -67,9 +67,7 @@ describe('mutationOptions', () => {
 return{name: 'onMutateResult'}
 },
 onSuccess: (_data,_variables,onMutateResult)=>{
-expectTypeOf(onMutateResult).toEqualTypeOf<
-{name: string}|undefined
->()
+expectTypeOf(onMutateResult).toEqualTypeOf<{name: string}>()
 },
 })
 })

packages/query-core/src/__tests__/mutation.test-d.tsx

@@ -0,0 +1,96 @@
+import{describe,expectTypeOf,it}from'vitest'
+import{QueryClient}from'../queryClient'
+import{MutationObserver}from'../mutationObserver'
+
+describe('mutation',()=>{
+describe('onMutate',()=>{
+it('should have onMutateResult undefined if undefined is explicitly returned',()=>{
+newMutationObserver(newQueryClient(),{
+mutationFn: (variables: number)=>{
+returnPromise.resolve(String(variables))
+},
+onMutate: ()=>{
+returnundefined
+},
+onSuccess: (data,variables,onMutateResult)=>{
+expectTypeOf(data).toEqualTypeOf<string>()
+expectTypeOf(variables).toEqualTypeOf<number>()
+expectTypeOf(onMutateResult).toEqualTypeOf<undefined>()
+},
+onError: (_data,_variables,onMutateResult)=>{
+expectTypeOf(onMutateResult).toEqualTypeOf<undefined>()
+},
+onSettled: (_data,_error,_variables,onMutateResult)=>{
+expectTypeOf(onMutateResult).toEqualTypeOf<undefined>()
+},
+})
+})
+
+it('should have unknown onMutateResult if onMutate is left out',()=>{
+newMutationObserver(newQueryClient(),{
+mutationFn: (variables: number)=>{
+returnPromise.resolve(String(variables))
+},
+onSuccess: (_data,_variables,onMutateResult)=>{
+expectTypeOf(onMutateResult).toEqualTypeOf<unknown>()
+},
+onError: (_data,_variables,onMutateResult)=>{
+expectTypeOf(onMutateResult).toEqualTypeOf<unknown>()
+},
+onSettled: (_data,_error,_variables,onMutateResult)=>{
+expectTypeOf(onMutateResult).toEqualTypeOf<unknown>()
+},
+})
+})
+
+it('should infer onMutateResult',()=>{
+newMutationObserver(newQueryClient(),{
+mutationFn: (variables: number)=>{
+returnPromise.resolve(String(variables))
+},
+onMutate: ()=>{
+returnPromise.resolve({foo: 'bar'})
+},
+onSuccess: (_data,_variables,onMutateResult)=>{
+expectTypeOf(onMutateResult).toEqualTypeOf<{foo: string}>()
+},
+onError: (_data,_variables,onMutateResult)=>{
+expectTypeOf(onMutateResult).toEqualTypeOf<
+{foo: string}|undefined
+>()
+},
+onSettled: (_data,_error,_variables,onMutateResult)=>{
+expectTypeOf(onMutateResult).toEqualTypeOf<
+{foo: string}|undefined
+>()
+},
+})
+})
+
+it('should include undefined in the union if explicitly returned',()=>{
+newMutationObserver(newQueryClient(),{
+mutationFn: (variables: number)=>{
+returnPromise.resolve(String(variables))
+},
+onMutate: ()=>{
+returnMath.random()>0.5 ? {foo: 'bar'} : undefined
+},
+onSuccess: (_data,_variables,onMutateResult)=>{
+expectTypeOf(onMutateResult).toEqualTypeOf<
+{foo: string}|undefined
+>()
+},
+onError: (_data,_variables,onMutateResult)=>{
+expectTypeOf(onMutateResult).toEqualTypeOf<
+{foo: string}|undefined
+>()
+},
+onSettled: (_data,_error,_variables,onMutateResult)=>{
+expectTypeOf(onMutateResult).toEqualTypeOf<
+{foo: string}|undefined
+>()
+},
+})
+})
+})
+})

packages/query-core/src/mutation.ts

@@ -244,7 +244,7 @@ export class Mutation<
 awaitthis.options.onSuccess?.(
 data,
 variables,
-this.state.context,
+this.state.context!,
 mutationFnContext,
 )
 

packages/query-core/src/types.ts

@@ -1113,11 +1113,11 @@ export interface MutationOptions<
 onMutate?: (
 variables: TVariables,
 context: MutationFunctionContext,
-)=>Promise<TOnMutateResult|undefined>|TOnMutateResult|undefined
+)=>Promise<TOnMutateResult>|TOnMutateResult
 onSuccess?: (
 data: TData,
 variables: TVariables,
-onMutateResult: TOnMutateResult|undefined,
+onMutateResult: TOnMutateResult,
 context: MutationFunctionContext,
 )=>Promise<unknown>|unknown
 onError?: (

packages/react-query/src/__tests__/mutationOptions.test-d.tsx

@@ -63,9 +63,7 @@ describe('mutationOptions', () => {
 return{name: 'onMutateResult'}
 },
 onSuccess: (_data,_variables,onMutateResult)=>{
-expectTypeOf(onMutateResult).toEqualTypeOf<
-{name: string}|undefined
->()
+expectTypeOf(onMutateResult).toEqualTypeOf<{name: string}>()
 },
 })
 })