feat: never type (#8)

package.json

@@ -73,6 +73,7 @@
     "@vitest/coverage-v8": "^2.1.8",
     "cross-env": "^7.0.3",
     "eslint": "^9.16.0",
+    "fast-check": "^3.23.1",
     "prettier": "^3.4.1",
     "source-map-support": "^0.5.21",
     "tomer": "^6.1.1",

src/arbitrary.ts

@@ -9,6 +9,7 @@ export type Arbitrary = BaseArbitrary &
   (
     | NullArbitrary
     | UndefinedArbitrary
+    | NeverArbitrary
     | BooleanArbitrary
     | NumberArbitrary
     | BigIntArbitrary
@@ -33,6 +34,10 @@ export type UndefinedArbitrary = {
   type: `undefined`
 }
 
+export type NeverArbitrary = {
+  type: `never`
+}
+
 export type BooleanArbitrary = {
   type: `boolean`
 }

src/components.ts

@@ -37,7 +37,7 @@ const ArbitraryFile = ({
   sharedArbitraries: ReadonlySet<Arbitrary>
 }): Child =>
   ay.Output().children(ts.SourceFile({ path: `arbitraries.js` }).code`
-    import * as fc from 'fast-check'
+    import * as fc from 'fast-check';
 
     ${GlobalArbitraryNamespace({ namespace, sharedArbitraries })}
   `)
@@ -142,6 +142,8 @@ const ArbitraryDefinition = ({
       return NullArbitrary()
     case `undefined`:
       return UndefinedArbitrary()
+    case `never`:
+      return NeverArbitrary()
     case `boolean`:
       return BooleanArbitrary()
     case `number`:
@@ -169,6 +171,12 @@ const NullArbitrary = (): Child => code`fc.constant(null)`
 
 const UndefinedArbitrary = (): Child => code`fc.constant(undefined)`
 
+const NeverArbitrary = (): Child => code`
+  fc.constant(null).map(() => {
+    throw new Error('never');
+  })
+`
+
 const BooleanArbitrary = (): Child => code`fc.boolean()`
 
 const NumberArbitrary = ({

src/convert.ts

@@ -119,8 +119,9 @@ const convertIntrinsic = (intrinsic: IntrinsicType): Arbitrary => {
       return convertNull(intrinsic)
     case `void`:
       return convertVoid(intrinsic)
-    case `ErrorType`:
     case `never`:
+      return convertNever(intrinsic)
+    case `ErrorType`:
     case `unknown`:
       throw new Error(`Unhandled Intrinsic: ${intrinsic.name}`)
   }
@@ -132,6 +133,9 @@ const convertNull = ($null: IntrinsicType): Arbitrary =>
 const convertVoid = ($void: IntrinsicType): Arbitrary =>
   memoize({ type: `undefined`, name: $void.name })
 
+const convertNever = (never: IntrinsicType): Arbitrary =>
+  memoize({ type: `never`, name: never.name })
+
 const convertScalar = (
   program: Program,
   scalar: Scalar,
@@ -306,6 +310,8 @@ const getArbitraryKey = (arbitrary: Arbitrary): ArbitraryKey => {
       return keyalesce([arbitrary.type, arbitrary.name])
     case `undefined`:
       return keyalesce([arbitrary.type, arbitrary.name])
+    case `never`:
+      return keyalesce([arbitrary.type, arbitrary.name])
     case `boolean`:
       return keyalesce([arbitrary.type, arbitrary.name])
     case `number`:
@@ -424,6 +430,7 @@ const getDirectArbitraryDependencies = (
   switch (arbitrary.type) {
     case `null`:
     case `undefined`:
+    case `never`:
     case `boolean`:
     case `number`:
     case `bigint`:

test/index.ts

@@ -78,6 +78,14 @@ test.each([
       }
     `,
   },
+  {
+    name: `never`,
+    code: `
+      model M {
+        property: never
+      }
+    `,
+  },
   {
     name: `boolean`,
     code: `

test/snapshots/boolean.js

@@ -1,3 +1,3 @@
-import * as fc from 'fast-check'
+import * as fc from 'fast-check';
 
 export const Boolean = fc.boolean();

test/snapshots/bytes.js

@@ -1,3 +1,3 @@
-import * as fc from 'fast-check'
+import * as fc from 'fast-check';
 
 export const Bytes = fc.uint8Array();

test/snapshots/decimal.js

@@ -1,4 +1,4 @@
-import * as fc from 'fast-check'
+import * as fc from 'fast-check';
 
 export const Decimal = fc.double();
 

test/snapshots/decimal128.js

@@ -1,4 +1,4 @@
-import * as fc from 'fast-check'
+import * as fc from 'fast-check';
 
 export const Decimal128 = fc.double();
 

test/snapshots/empty.js

@@ -1,2 +1,2 @@
-import * as fc from 'fast-check'
+import * as fc from 'fast-check';
 

test/snapshots/file-model.js

@@ -1,4 +1,4 @@
-import * as fc from 'fast-check'
+import * as fc from 'fast-check';
 
 export const Pet = fc.record({
 

test/snapshots/file-namespace.js

@@ -1,4 +1,4 @@
-import * as fc from 'fast-check'
+import * as fc from 'fast-check';
 
 export const PetStore = {
 

test/snapshots/float32.js

@@ -1,4 +1,4 @@
-import * as fc from 'fast-check'
+import * as fc from 'fast-check';
 
 export const Float32 = fc.float();
 

test/snapshots/float64.js

@@ -1,4 +1,4 @@
-import * as fc from 'fast-check'
+import * as fc from 'fast-check';
 
 export const Float64 = fc.double();
 

test/snapshots/int16.js

@@ -1,4 +1,4 @@
-import * as fc from 'fast-check'
+import * as fc from 'fast-check';
 
 export const Int16 = fc.integer({
   min: -32768,

test/snapshots/int32.js

@@ -1,4 +1,4 @@
-import * as fc from 'fast-check'
+import * as fc from 'fast-check';
 
 export const Int32 = fc.integer();
 

test/snapshots/int64.js

@@ -1,4 +1,4 @@
-import * as fc from 'fast-check'
+import * as fc from 'fast-check';
 
 export const Int64 = fc.bigInt({
   min: -9223372036854775808n,

test/snapshots/int8.js

@@ -1,4 +1,4 @@
-import * as fc from 'fast-check'
+import * as fc from 'fast-check';
 
 export const Int8 = fc.integer({
   min: -128,

test/snapshots/integer.js

@@ -1,4 +1,4 @@
-import * as fc from 'fast-check'
+import * as fc from 'fast-check';
 
 export const Integer = fc.bigInt();
 

test/snapshots/model-and-namespace.js

@@ -1,4 +1,4 @@
-import * as fc from 'fast-check'
+import * as fc from 'fast-check';
 
 export const PetStore = {
 

test/snapshots/model-in-namespace.js

@@ -1,4 +1,4 @@
-import * as fc from 'fast-check'
+import * as fc from 'fast-check';
 
 export const PetStore = {
   Pet: fc.record({

test/snapshots/model.js

@@ -1,4 +1,4 @@
-import * as fc from 'fast-check'
+import * as fc from 'fast-check';
 
 export const Dog = fc.record({
   name: fc.string({

test/snapshots/namespace-in-file-namespace.js

@@ -1,4 +1,4 @@
-import * as fc from 'fast-check'
+import * as fc from 'fast-check';
 
 export const PetStore = {
   Pets: {

test/snapshots/namespace.js

@@ -1,4 +1,4 @@
-import * as fc from 'fast-check'
+import * as fc from 'fast-check';
 
 export const PetStore = {
 

test/snapshots/never.js

@@ -0,0 +1,7 @@
+import * as fc from 'fast-check';
+
+export const M = fc.record({
+  property: fc.constant(null).map(() => {
+    throw new Error('never');
+  }),
+});

test/snapshots/null.js

@@ -1,4 +1,4 @@
-import * as fc from 'fast-check'
+import * as fc from 'fast-check';
 
 export const M = fc.record({
   property: fc.constant(null),

test/snapshots/numeric.js

@@ -1,4 +1,4 @@
-import * as fc from 'fast-check'
+import * as fc from 'fast-check';
 
 export const Numeric = fc.double();
 

test/snapshots/safeint.js

@@ -1,4 +1,4 @@
-import * as fc from 'fast-check'
+import * as fc from 'fast-check';
 
 export const SafeInt = fc.maxSafeInteger();
 

test/snapshots/string.js

@@ -1,4 +1,4 @@
-import * as fc from 'fast-check'
+import * as fc from 'fast-check';
 
 export const String = fc.string();
 

test/snapshots/void.js

@@ -1,4 +1,4 @@
-import * as fc from 'fast-check'
+import * as fc from 'fast-check';
 
 export const M = fc.record({
   property: fc.constant(undefined),