test: improve type builder unit tests

packages/openapi-code-generator/package.json

@@ -58,7 +58,6 @@
     "@typespec/versioning": "0.77.0",
     "@typespec/xml": "0.77.0",
     "joi": "^18.0.2",
-    "piscina": "^5.1.4",
     "tsx": "^4.21.0"
   },
   "dependencies": {

packages/openapi-code-generator/src/core/input.ts

@@ -60,7 +60,11 @@ export type InputConfig = {
   enumExtensibility: "open" | "closed"
 }
 
-export class Input {
+export interface ISchemaProvider {
+  schema(maybeRef: MaybeIRModel): IRModel
+}
+
+export class Input implements ISchemaProvider {
   constructor(
     private loader: OpenapiLoader,
     readonly config: InputConfig,

packages/openapi-code-generator/src/test/ir-model.fixtures.test-utils.ts

@@ -4,11 +4,13 @@ import type {
   IRModelBoolean,
   IRModelIntersection,
   IRModelNever,
+  IRModelNull,
   IRModelNumeric,
   IRModelObject,
   IRModelRecord,
   IRModelString,
   IRModelUnion,
+  IRRef,
 } from "../core/openapi-types-normalized"
 
 const base = {
@@ -110,9 +112,20 @@ const extension = {
     default: undefined,
     "x-internal-preprocess": undefined,
   } satisfies IRModelUnion,
+  null: {
+    isIRModel: true,
+    type: "null",
+    nullable: false,
+  } satisfies IRModelNull,
 }
 
 export const irFixture = {
+  ref(path: string, file = ""): IRRef {
+    return {
+      $ref: `${file}#${path}`,
+      "x-internal-preprocess": undefined,
+    }
+  },
   any(partial: Partial<IRModelAny> = {}): IRModelAny {
     return {...base.any, ...partial}
   },
@@ -147,4 +160,7 @@ export const irFixture = {
   union(partial: Partial<IRModelUnion> = {}): IRModelUnion {
     return {...extension.union, ...partial}
   },
+  null(partial: Partial<IRModelNull> = {}): IRModelNull {
+    return {...extension.null, ...partial}
+  },
 }

packages/openapi-code-generator/src/test/typescript-compiler.test-utils.spec.ts

@@ -0,0 +1,34 @@
+import {describe, expect, it} from "@jest/globals"
+import {TestOutputTypeChecker} from "./typescript-compiler.test-utils"
+
+describe("test/typescript-compiler", () => {
+  const typechecker = new TestOutputTypeChecker()
+
+  it("should throw is provided code doesn't typecheck successfully", async () => {
+    expect(() =>
+      typechecker.typecheck([
+        {
+          filename: "unit-test.ts",
+          content: `
+          const x = "foo"
+          const y: number = x
+        `,
+        },
+      ]),
+    ).toThrow(/TS2322: Type 'string' is not assignable to type 'number'/)
+  })
+
+  it("should not throw if the provided code is valid", async () => {
+    expect(() =>
+      typechecker.typecheck([
+        {
+          filename: "unit-test.ts",
+          content: `
+            const x = "foo"
+            const y: string = x
+        `,
+        },
+      ]),
+    ).not.toThrow()
+  })
+})

packages/openapi-code-generator/src/test/typescript-compiler.test-utils.ts

@@ -0,0 +1,103 @@
+import fs from "node:fs"
+import path from "node:path"
+import util from "node:util"
+import ts from "typescript"
+
+export class TestOutputTypeChecker {
+  private files: Record<string, string> = {}
+  private readonly sourceFileCache: Record<string, ts.SourceFile | undefined> =
+    {}
+
+  private readonly compilerHost: ts.CompilerHost
+  private readonly options: ts.CompilerOptions = {
+    noEmit: true,
+    strict: true,
+    target: ts.ScriptTarget.ESNext,
+    module: ts.ModuleKind.CommonJS,
+    skipLibCheck: true,
+    types: [],
+  }
+  private program: ts.Program
+
+  constructor() {
+    const defaultHost = ts.createCompilerHost(this.options, true)
+
+    const compilerHost = {
+      ...defaultHost,
+      fileExists: (fileName: string) => {
+        return fileName in this.files
+      },
+      readFile: (fileName: string): string => {
+        const file = this.files[fileName]
+
+        if (file === undefined && fileName.startsWith("/")) {
+          return fs.readFileSync(fileName, "utf-8").toString()
+        }
+
+        if (file === undefined) {
+          throw new Error(`file '${fileName}' not found`)
+        }
+
+        return file
+      },
+      writeFile: () => {
+        /* noop */
+      },
+      getSourceFile: (fileName, languageVersion) => {
+        if (this.sourceFileCache[fileName]) {
+          return this.sourceFileCache[fileName]
+        }
+
+        const file = compilerHost.readFile(fileName)
+        const result = ts.createSourceFile(fileName, file, languageVersion)
+        this.sourceFileCache[fileName] = result
+
+        return result
+      },
+    } satisfies ts.CompilerHost
+
+    this.compilerHost = compilerHost
+    this.program = ts.createProgram({
+      rootNames: [],
+      options: this.options,
+      host: this.compilerHost,
+    })
+  }
+
+  typecheck(compilationUnits: {filename: string; content: string}[]) {
+    const rootNames: string[] = []
+
+    for (const filename in this.files) {
+      this.sourceFileCache[filename] = undefined
+    }
+
+    this.files = {}
+
+    for (const unit of compilationUnits) {
+      const filename = path.resolve(unit.filename)
+      this.files[filename] = unit.content
+      this.sourceFileCache[filename] = undefined
+      rootNames.push(filename)
+    }
+
+    this.program = ts.createProgram({
+      rootNames,
+      options: this.options,
+      host: this.compilerHost,
+      oldProgram: this.program,
+    })
+
+    const diagnostics = ts.getPreEmitDiagnostics(this.program)
+
+    if (diagnostics.length > 0) {
+      const formatted = ts.formatDiagnosticsWithColorAndContext(diagnostics, {
+        getCurrentDirectory: () => "",
+        getCanonicalFileName: (fileName) => fileName,
+        getNewLine: () => "\n",
+      })
+      throw new Error(
+        `TypeScript compilation failed:\n\n${util.stripVTControlCharacters(formatted)}`,
+      )
+    }
+  }
+}

packages/openapi-code-generator/src/typescript/client/abstract-client-builder.ts

@@ -3,7 +3,7 @@ import type {IROperation} from "../../core/openapi-types-normalized"
 import {CompilationUnit, type ICompilable} from "../common/compilation-units"
 import type {ImportBuilder} from "../common/import-builder"
 import type {SchemaBuilder} from "../common/schema-builders/schema-builder"
-import type {TypeBuilder} from "../common/type-builder"
+import type {TypeBuilder} from "../common/type-builder/type-builder"
 import {union} from "../common/type-utils"
 import {ClientOperationBuilder} from "./client-operation-builder"
 import {ClientServersBuilder} from "./client-servers-builder"

packages/openapi-code-generator/src/typescript/client/client-operation-builder.ts

@@ -8,7 +8,7 @@ import type {
 import {extractPlaceholders} from "../../core/openapi-utils"
 import {camelCase, isDefined} from "../../core/utils"
 import type {SchemaBuilder} from "../common/schema-builders/schema-builder"
-import type {TypeBuilder} from "../common/type-builder"
+import type {TypeBuilder} from "../common/type-builder/type-builder"
 import {object, quotedStringLiteral} from "../common/type-utils"
 import {
   combineParams,

packages/openapi-code-generator/src/typescript/client/typescript-angular/typescript-angular.generator.ts

@@ -2,7 +2,7 @@ import {titleCase} from "../../../core/utils"
 import type {OpenapiTypescriptGeneratorConfig} from "../../../templates.types"
 import {ImportBuilder} from "../../common/import-builder"
 import {schemaBuilderFactory} from "../../common/schema-builders/schema-builder"
-import {TypeBuilder} from "../../common/type-builder"
+import {TypeBuilder} from "../../common/type-builder/type-builder"
 import {AngularModuleBuilder} from "./angular-module-builder"
 import {AngularServiceBuilder} from "./angular-service-builder"
 
@@ -17,7 +17,7 @@ export async function generateTypescriptAngular(
   const moduleImports = new ImportBuilder(importBuilderConfig)
   const serviceImports = new ImportBuilder(importBuilderConfig)
 
-  const rootTypeBuilder = await TypeBuilder.fromInput(
+  const rootTypeBuilder = await TypeBuilder.fromSchemaProvider(
     "./models.ts",
     input,
     config.compilerOptions,

packages/openapi-code-generator/src/typescript/client/typescript-axios/typescript-axios.generator.ts

@@ -2,7 +2,7 @@ import {titleCase} from "../../../core/utils"
 import type {OpenapiTypescriptGeneratorConfig} from "../../../templates.types"
 import {ImportBuilder} from "../../common/import-builder"
 import {schemaBuilderFactory} from "../../common/schema-builders/schema-builder"
-import {TypeBuilder} from "../../common/type-builder"
+import {TypeBuilder} from "../../common/type-builder/type-builder"
 import {TypescriptAxiosClientBuilder} from "./typescript-axios-client-builder"
 
 export async function generateTypescriptAxios(
@@ -15,7 +15,7 @@ export async function generateTypescriptAxios(
   const schemaBuilderImports = new ImportBuilder(importBuilderConfig)
   const clientImports = new ImportBuilder(importBuilderConfig)
 
-  const rootTypeBuilder = await TypeBuilder.fromInput(
+  const rootTypeBuilder = await TypeBuilder.fromSchemaProvider(
     "./models.ts",
     input,
     config.compilerOptions,