fix(types): do not erase component type constraint

Author: mcous

src/__tests__/render.test-d.ts

@@ -18,6 +18,14 @@ describe('types', () => {
     await rerender({ count: 0 })
   })
 
+  test('non-components are rejected', () => {
+    // eslint-disable-next-line @typescript-eslint/no-extraneous-class
+    class NotComponent {}
+
+    // @ts-expect-error: component should be a Svelte component
+    subject.render(NotComponent)
+  })
+
   test('invalid prop types are rejected', () => {
     // @ts-expect-error: name should be a string
     subject.render(Component, { name: 42 })

src/component-types.d.ts

@@ -1,17 +1,23 @@
 /* eslint-disable @typescript-eslint/no-explicit-any, @typescript-eslint/no-redundant-type-constituents */
-import type * as Svelte from 'svelte'
+import type {
+  Component as ModernComponent,
+  ComponentConstructorOptions as LegacyConstructorOptions,
+  ComponentProps,
+  mount,
+  SvelteComponent as LegacyComponent,
+} from 'svelte'
 
-type IS_MODERN_SVELTE = Svelte.Component extends (...args: any[]) => any
+type IS_MODERN_SVELTE = ModernComponent extends (...args: any[]) => any
   ? true
   : false
 
 /** A compiled, imported Svelte component. */
 export type Component<
-  P extends Record<string, any>,
-  E extends Record<string, any>,
+  P extends Record<string, any> = any,
+  E extends Record<string, any> = any,
 > = IS_MODERN_SVELTE extends true
-  ? Svelte.Component<P, E> | Svelte.SvelteComponent<P>
-  : Svelte.SvelteComponent<P>
+  ? ModernComponent<P, E> | LegacyComponent<P>
+  : LegacyComponent<P>
 
 /**
  * The type of an imported, compiled Svelte component.
@@ -24,17 +30,17 @@ export type ComponentType<C> = IS_MODERN_SVELTE extends true
   : new (...args: any[]) => C
 
 /** The props of a component. */
-export type Props<C extends Component<any, any>> = Svelte.ComponentProps<C>
+export type Props<C extends Component> = ComponentProps<C>
 
 /**
  * The exported fields of a component.
  *
  * In Svelte 5, this is the set of variables marked as `export`'d.
  * In Svelte 4, this is simply the instance of the component class.
  */
-export type Exports<C> = C extends Svelte.SvelteComponent
+export type Exports<C> = C extends LegacyComponent
   ? C
-  : C extends Svelte.Component<any, infer E>
+  : C extends ModernComponent<any, infer E>
     ? E
     : never
 
@@ -43,7 +49,6 @@ export type Exports<C> = C extends Svelte.SvelteComponent
  *
  * In Svelte 4, these are the options passed to the component constructor.
  */
-export type MountOptions<C extends Component<any, any>> =
-  IS_MODERN_SVELTE extends true
-    ? Parameters<typeof Svelte.mount<Props<C>, Exports<C>>>[1]
-    : Svelte.ComponentConstructorOptions<Props<C>>
+export type MountOptions<C extends Component> = IS_MODERN_SVELTE extends true
+  ? Parameters<typeof mount<Props<C>, Exports<C>>>[1]
+  : LegacyConstructorOptions<Props<C>>