Add type assertions

src/libs/actions/OnyxDerived.ts

@@ -4,9 +4,11 @@ import OnyxUtils from 'react-native-onyx/dist/OnyxUtils';
 import type {NonEmptyTuple, ValueOf} from 'type-fest';
 import {isThread} from '@libs/ReportUtils';
 import CONST from '@src/CONST';
-import type {GetOnyxTypeForKey, OnyxDerivedValuesMapping, OnyxKey} from '@src/ONYXKEYS';
+import type {GetOnyxTypeForKey, OnyxDerivedKey, OnyxDerivedValuesMapping, OnyxKey} from '@src/ONYXKEYS';
 import ONYXKEYS from '@src/ONYXKEYS';
+import type AssertTypesEqual from '@src/types/utils/AssertTypesEqual';
 import ObjectUtils from '@src/types/utils/ObjectUtils';
+import type SymmetricDifference from '@src/types/utils/SymmetricDifference';
 
 /**
  * A derived value configuration describes:
@@ -82,6 +84,9 @@ function getOnyxValues<Keys extends readonly OnyxKey[]>(keys: Keys): Promise<{[I
     return Promise.all(keys.map((key) => OnyxUtils.get(key))) as Promise<{[Index in keyof Keys]: GetOnyxTypeForKey<Keys[Index]>}>;
 }
 
+/**
+ * Initialize all Onyx derived values, store them in Onyx, and setup listeners to update them when dependencies change.
+ */
 function init() {
     for (const [key, {compute, dependencies}] of ObjectUtils.typedEntries(ONYX_DERIVED_VALUES)) {
         // Create an array to hold the current values for each dependency.
@@ -136,3 +141,28 @@ function init() {
 }
 
 export default init;
+
+// Note: we can't use `as const satisfies...` for ONYX_DERIVED_VALUES without losing type specificity.
+// So these type assertions are here to help enforce that ONYX_DERIVED_VALUES has all the keys and the correct types,
+// according to the type definitions for derived keys in ONYXKEYS.ts.
+type MismatchedDerivedKeysError =
+    `Error: ONYX_DERIVED_VALUES does not match ONYXKEYS.DERIVED or OnyxDerivedValuesMapping. The following keys are present in one or the other, but not both: ${SymmetricDifference<
+        keyof typeof ONYX_DERIVED_VALUES,
+        OnyxDerivedKey
+    >}`;
+// eslint-disable-next-line @typescript-eslint/no-unused-vars
+type KeyAssertion = AssertTypesEqual<keyof typeof ONYX_DERIVED_VALUES, OnyxDerivedKey, MismatchedDerivedKeysError>;
+
+type ExpectedDerivedValueComputeReturnTypes = {
+    [Key in keyof OnyxDerivedValuesMapping]: OnyxEntry<OnyxDerivedValuesMapping[Key]>;
+};
+type ActualDerivedValueComputeReturnTypes = {
+    [Key in keyof typeof ONYX_DERIVED_VALUES]: ReturnType<(typeof ONYX_DERIVED_VALUES)[Key]['compute']>;
+};
+type MismatchedDerivedValues = {
+    [Key in keyof ExpectedDerivedValueComputeReturnTypes]: ExpectedDerivedValueComputeReturnTypes[Key] extends ActualDerivedValueComputeReturnTypes[Key] ? never : Key;
+}[keyof ExpectedDerivedValueComputeReturnTypes];
+type MismatchedDerivedValuesError =
+    `Error: ONYX_DERIVED_VALUES does not match OnyxDerivedValuesMapping. The following configs have compute functions that do not return the correct type according to OnyxDerivedValuesMapping: ${MismatchedDerivedValues}`;
+// eslint-disable-next-line @typescript-eslint/no-unused-vars
+type ComputeReturnTypeAssertion = AssertTypesEqual<MismatchedDerivedValues, never, MismatchedDerivedValuesError>;

src/types/utils/SymmetricDifference.ts

@@ -0,0 +1,3 @@
+type SymmetricDifference<A, B> = Exclude<A, B> | Exclude<B, A>;
+
+export default SymmetricDifference;