test: branding example

mmkal · Oct 9, 2020 · 61489a1 · 61489a1
1 parent d1d85ab
commit 61489a1
Showing 1 changed file with 29 additions and 6 deletions.
diff --git a/packages/typegen/test/index.test.ts b/packages/typegen/test/index.test.ts
@@ -6,11 +6,31 @@ import {join} from 'path'
 import {tmpdir} from 'os'
 import {expectTypeOf} from 'expect-type'
 
+type Brands = {
+  CountInfo: {
+    a_count: 'count'
+  }
+}
+
+type Branded<T, TypeName, Field> = TypeName extends keyof Brands
+  ? Field extends keyof Brands[TypeName]
+    ? T & {_brand: Brands[TypeName][Field]}
+    : T
+  : T
+
+type OrigKnownTypes = typeof knownTypes
+
+type WrappedKnownTypes = {
+  [TypeName in keyof OrigKnownTypes]: {
+    [Field in keyof OrigKnownTypes[TypeName]]: Branded<OrigKnownTypes[TypeName][Field], TypeName, Field>
+  }
+}
+
 describe('type generator', () => {
   const writeTypes = join(__dirname, 'generated/main')
   const {sql, poolConfig} = setupTypeGen({
     reset: true,
-    knownTypes,
+    knownTypes: knownTypes as WrappedKnownTypes,
     writeTypes,
   })
   const connectionString = `postgresql://postgres:postgres@localhost:5433/postgres`
@@ -47,11 +67,14 @@ describe('type generator', () => {
     await slonik.query(sql.Foo`select * from foo`) // make sure duplicate doesn't create two types.
 
     const countInfo = await slonik.one(sql.CountInfo`
-      select count(*) as a_count, a as a_value
-      from foo
-      group by a
-    `)
-    expectTypeOf(countInfo).toEqualTypeOf<{a_count: number; a_value: string}>()
+  select count(*) as a_count, a as a_value
+  from foo
+  group by a
+`)
+    expectTypeOf(countInfo).toEqualTypeOf<{
+      a_count: number & {_brand: 'count'}
+      a_value: string
+    }>()
 
     const generatedFiles = readdirSync(writeTypes)
     generatedFiles.forEach(f => {