feat: null intrinsic

src/arbitrary.ts

@@ -75,3 +75,7 @@ export type StringArbitrary = {
 export type BooleanArbitrary = {
   type: `boolean`
 }
+
+export type NullArbitrary = {
+  type: `null`
+}

src/components.ts

@@ -158,6 +158,8 @@ const ArbitraryDefinition = ({
       return StringArbitrary({ arbitrary })
     case `boolean`:
       return BooleanArbitrary()
+    case `null`:
+      return NullArbitrary()
   }
 }
 
@@ -297,6 +299,8 @@ const StringArbitrary = ({
 
 const BooleanArbitrary = (): Child => code`fc.boolean()`
 
+const NullArbitrary = (): Child => code`fc.constant(null)`
+
 const Options = ({
   properties,
   emitEmpty = false,

src/convert.ts

@@ -7,6 +7,7 @@ import {
 } from '@typespec/compiler'
 import type {
   Enum,
+  IntrinsicType,
   Model,
   Namespace,
   Numeric,
@@ -101,6 +102,8 @@ const convertType = (
       return convertEnum(type, options)
     case `Scalar`:
       return convertScalar(program, type, options)
+    case `Intrinsic`:
+      return convertIntrinsic(type)
   }
 
   throw new Error(`Unhandled type: ${type.kind}`)
@@ -250,6 +253,21 @@ const convertString = (
 const convertBoolean = (boolean: Scalar): Arbitrary =>
   memoize({ type: `boolean`, name: boolean.name })
 
+const convertIntrinsic = (intrinsic: IntrinsicType): Arbitrary => {
+  switch (intrinsic.name) {
+    case `null`:
+      return convertNull(intrinsic)
+    case `ErrorType`:
+    case `void`:
+    case `never`:
+    case `unknown`:
+      throw new Error(`Unhandled Intrinsic: ${intrinsic.name}`)
+  }
+}
+
+const convertNull = ($null: IntrinsicType): Arbitrary =>
+  memoize({ type: `null`, name: $null.name })
+
 const getConstraints = (program: Program, type: Type): Constraints =>
   pipe(
     entries({
@@ -324,6 +342,8 @@ const getArbitraryKey = (arbitrary: Arbitrary): ArbitraryKey => {
       ])
     case `boolean`:
       return keyalesce([arbitrary.type, arbitrary.name])
+    case `null`:
+      return keyalesce([arbitrary.type, arbitrary.name])
   }
 }
 
@@ -410,6 +430,7 @@ const getDirectArbitraryDependencies = (
     case `bytes`:
     case `string`:
     case `boolean`:
+    case `null`:
       return new Set()
   }
 }

test/index.ts

@@ -311,6 +311,14 @@ test.each([
       scalar Boolean extends boolean;
     `,
   },
+  {
+    name: `null`,
+    code: `
+      model M {
+        property: null
+      }
+    `,
+  },
 
   // Models
   {

test/snapshots/null.js

@@ -0,0 +1,5 @@
+import * as fc from 'fast-check'
+
+export const M = fc.record({
+  property: fc.constant(null),
+});