Enable useTsconfigDeclarationDir if declarationDir

src/createRollupConfig.ts

@@ -153,6 +153,9 @@ export async function createRollupConfig(
           },
         },
         check: opts.transpileOnly === false,
+        useTsconfigDeclarationDir: Boolean(
+          tsconfigJSON?.compilerOptions?.declarationDir
+        ),
       }),
       babelPluginTsdx({
         exclude: 'node_modules/**',

test/fixtures/build-declarationDir/package.json

@@ -0,0 +1,7 @@
+{
+  "scripts": {
+    "build": "tsdx build"
+  },
+  "name": "build-declarationdir",
+  "license": "MIT"
+}

test/fixtures/build-declarationDir/src/foo.ts

@@ -0,0 +1 @@
+export const foo = () => 'bar';

test/fixtures/build-declarationDir/src/index.ts

@@ -0,0 +1,11 @@
+import './syntax/nullish-coalescing';
+import './syntax/optional-chaining';
+
+export { foo } from './foo';
+
+export const sum = (a: number, b: number) => {
+  if ('development' === process.env.NODE_ENV) {
+    console.log('fuck');
+  }
+  return a + b;
+};

test/fixtures/build-declarationDir/src/syntax/nullish-coalescing.ts

@@ -0,0 +1,5 @@
+// https://www.typescriptlang.org/docs/handbook/release-notes/typescript-3-7.html#nullish-coalescing
+
+const bar = () => {};
+const foo = false;
+export const x = foo ?? bar();

test/fixtures/build-declarationDir/src/syntax/optional-chaining.ts

@@ -0,0 +1,3 @@
+// https://www.typescriptlang.org/docs/handbook/release-notes/typescript-3-7.html#optional-chaining
+
+export const foo = (foo?: { bar: string }) => foo?.bar || 'bar';

test/fixtures/build-declarationDir/test/blah.test.ts

@@ -0,0 +1,7 @@
+import { sum } from '../src';
+
+describe('fuck', () => {
+  it('works', () => {
+    expect(sum(1, 1)).toEqual(2);
+  });
+});

test/fixtures/build-declarationDir/tsconfig.json

@@ -0,0 +1,28 @@
+{
+  "compilerOptions": {
+    "target": "es5",
+    "module": "ESNext",
+    "lib": ["dom", "esnext"],
+    "declaration": true,
+    "declarationDir": "typings",
+    "declarationMap": true,
+    "sourceMap": true,
+    "rootDir": "./src",
+    "strict": true,
+    "noImplicitAny": true,
+    "strictNullChecks": true,
+    "strictFunctionTypes": true,
+    "strictPropertyInitialization": true,
+    "noImplicitThis": true,
+    "alwaysStrict": true,
+    "noUnusedLocals": true,
+    "noUnusedParameters": true,
+    "noImplicitReturns": true,
+    "noFallthroughCasesInSwitch": true,
+    "moduleResolution": "node",
+    "baseUrl": ".",
+    "jsx": "react",
+    "esModuleInterop": true
+  },
+  "include": ["src", "types"]
+}

test/tests/tsdx-build.test.js

@@ -102,6 +102,27 @@ describe('tsdx build', () => {
     expect(code).toBe(0);
   });
 
+  it('should use the declarationDir when set in tsconfig', () => {
+    util.setupStageWithFixture(stageName, 'build-declarationDir');
+
+    const output = shell.exec('node ../dist/index.js build --format esm,cjs');
+
+    expect(shell.test('-f', 'dist/index.js')).toBeTruthy();
+    expect(
+      shell.test('-f', 'dist/build-declarationdir.cjs.development.js')
+    ).toBeTruthy();
+    expect(
+      shell.test('-f', 'dist/build-declarationdir.cjs.production.min.js')
+    ).toBeTruthy();
+    expect(shell.test('-f', 'dist/build-declarationdir.esm.js')).toBeTruthy();
+
+    expect(shell.test('-f', 'dist/index.d.ts')).toBeFalsy();
+    expect(shell.test('-f', 'typings/index.d.ts')).toBeTruthy();
+    expect(shell.test('-f', 'typings/index.d.ts.map')).toBeTruthy();
+
+    expect(output.code).toBe(0);
+  });
+
   afterEach(() => {
     util.teardownStage(stageName);
   });