fix: exclude never from union's types

src/__tests__/union-schema.test.ts

@@ -0,0 +1,31 @@
+import {expect, test} from 'vitest'
+
+import {literal} from '../creators/literal'
+import {never} from '../creators/never'
+import {number} from '../creators/number'
+import {object} from '../creators/object'
+import {string} from '../creators/string'
+import {union} from '../creators/union'
+
+test('typed object union excludes never types', () => {
+  const unionSchema = union([
+    object({
+      _type: literal('ok'),
+      name: string(),
+    }),
+    never(),
+  ])
+  const neverType = unionSchema.union.find(schema => {
+    // @ts-expect-error - should not be in type system
+    return schema.typeName === 'never'
+  })
+  expect(neverType).toBeUndefined()
+})
+test('primitive union excludes never types', () => {
+  const unionSchema = union([string(), number(), never()])
+  const neverType = unionSchema.union.find(schema => {
+    // @ts-expect-error - should not be in type system
+    return schema.typeName === 'never'
+  })
+  expect(neverType).toBeUndefined()
+})

src/__tests__/union.types.test-d.ts

@@ -1,4 +1,4 @@
-import {test} from 'vitest'
+import {expectTypeOf, test} from 'vitest'
 
 import {boolean} from '../creators/boolean'
 import {literal} from '../creators/literal'
@@ -7,6 +7,8 @@ import {number} from '../creators/number'
 import {object} from '../creators/object'
 import {string} from '../creators/string'
 import {union} from '../creators/union'
+import {type SanityNever, type SanityObjectUnion} from '../defs'
+import {type ElementType} from '../helpers/utilTypes'
 
 test('primitive unions', () => {
   union([string(), union([number(), boolean()])])
@@ -27,3 +29,9 @@ test('object union of object union', () => {
     union([object({_type: literal('baz'), foo: string()}), never()]),
   ])
 })
+
+test('union type excludes never type', () => {
+  expectTypeOf<ElementType<SanityObjectUnion['union']>>()
+    .extract<SanityNever>()
+    .toEqualTypeOf<never>()
+})

src/creators/union.ts

@@ -94,7 +94,10 @@ export function union<
         isPrimitiveUnionSchema(schema),
     )
   ) {
-    return defineType({typeName: 'primitiveUnion', union: unionTypes}) as any
+    return defineType({
+      typeName: 'primitiveUnion',
+      union: unionTypes.filter(schema => !isNeverSchema(schema)),
+    }) as any
   }
 
   if (
@@ -109,7 +112,7 @@ export function union<
   ) {
     return defineType({
       typeName: 'union',
-      union: unionTypes,
+      union: unionTypes.filter(schema => !isNeverSchema(schema)),
     }) as any
   }
 

src/defs.ts

@@ -84,7 +84,7 @@ export interface SanityObjectUnion<
   Output = OutputOf<Def>,
 > extends SanityType<Output> {
   typeName: 'union'
-  union: Def[]
+  union: Exclude<Def, SanityNever>[]
 }
 export interface SanityPrimitiveUnion<
   Def extends SanityPrimitive | SanityLiteral | SanityNever =
@@ -94,7 +94,7 @@ export interface SanityPrimitiveUnion<
   Output = OutputOf<Def>,
 > extends SanityType<Output> {
   typeName: 'primitiveUnion'
-  union: Def[]
+  union: Exclude<Def, SanityNever>[]
 }
 
 export type SanityObjectShape = {[key: string]: SanityAny}