projen · mergify · Nov 11, 2020 · Nov 8, 2020 · Nov 8, 2020 · Nov 8, 2020
diff --git a/API.md b/API.md
@@ -7,6 +7,7 @@ Name|Description
 [AwsCdkConstructLibrary](#projen-awscdkconstructlibrary)|AWS CDK construct library project.
 [AwsCdkTypeScriptApp](#projen-awscdktypescriptapp)|AWS CDK app in TypeScript.
 [Component](#projen-component)|Represents a project component.
+[CompositeProject](#projen-compositeproject)|Creates a composite project.
 [ConstructLibrary](#projen-constructlibrary)|A multi-language library for CDK constructs.
 [ConstructLibraryAws](#projen-constructlibraryaws)|*No description*
 [ConstructLibraryCdk8s](#projen-constructlibrarycdk8s)|CDK8s construct library project.
@@ -55,6 +56,8 @@ Name|Description
 [AwsCdkConstructLibraryOptions](#projen-awscdkconstructlibraryoptions)|Options for the construct-lib-aws project.
 [AwsCdkTypeScriptAppOptions](#projen-awscdktypescriptappoptions)|*No description*
 [Catalog](#projen-catalog)|*No description*
+[CompositeProjectChild](#projen-compositeprojectchild)|Declares a sub-project of the composite project.
+[CompositeProjectOptions](#projen-compositeprojectoptions)|Options for `CompositeProject`.
 [ConstructLibraryAwsOptions](#projen-constructlibraryawsoptions)|*No description*
 [ConstructLibraryCdk8sOptions](#projen-constructlibrarycdk8soptions)|*No description*
 [ConstructLibraryOptions](#projen-constructlibraryoptions)|*No description*
@@ -527,6 +530,44 @@ synthesize(_outdir: string): void
 
 
 
+## class CompositeProject 🔹 <a id="projen-compositeproject"></a>
+
+Creates a composite project.
+
+__Extends__: [Project](#projen-project)
+
+### Initializer
+
+
+
+
+```ts
+new CompositeProject(options?: CompositeProjectOptions)
+```
+
+* **options** (<code>[CompositeProjectOptions](#projen-compositeprojectoptions)</code>)  *No description*
+  * **projects** (<code>Array<[CompositeProjectChild](#projen-compositeprojectchild)></code>)  Declaratively define sub-projects by their sub paths. __*Optional*__
+
+
+### Methods
+
+
+#### addProject(subPath, project)🔹 <a id="projen-compositeproject-addproject"></a>
+
+Adds a project as a sub-project at a sub path.
+
+```ts
+addProject(subPath: string, project: Project): void
+```
+
+* **subPath** (<code>string</code>)  *No description*
+* **project** (<code>[Project](#projen-project)</code>)  *No description*
+
+
+
+
+
+
 ## class ConstructLibrary 🔹 <a id="projen-constructlibrary"></a>
 
 A multi-language library for CDK constructs.
@@ -3711,6 +3752,33 @@ Name | Type | Description
 
 
 
+## struct CompositeProjectChild 🔹 <a id="projen-compositeprojectchild"></a>
+
+
+Declares a sub-project of the composite project.
+
+
+
+Name | Type | Description 
+-----|------|-------------
+**path**🔹 | <code>string</code> | Project subpath.
+**project**🔹 | <code>[Project](#projen-project)</code> | Projen project to synthesize in `path`.
+
+
+
+## struct CompositeProjectOptions 🔹 <a id="projen-compositeprojectoptions"></a>
+
+
+Options for `CompositeProject`.
+
+
+
+Name | Type | Description 
+-----|------|-------------
+**projects**?🔹 | <code>Array<[CompositeProjectChild](#projen-compositeprojectchild)></code> | Declaratively define sub-projects by their sub paths.<br/>__*Optional*__
+
+
+
 ## struct ConstructLibraryAwsOptions ⚠️ <a id="projen-constructlibraryawsoptions"></a>
 
 

diff --git a/README.md b/README.md
@@ -43,6 +43,7 @@ list):
 * [awscdk-app-ts](https://github.com/projen/projen/blob/master/API.md#projen-awscdktypescriptapp) - AWS CDK app in TypeScript.
 * [awscdk-construct](https://github.com/projen/projen/blob/master/API.md#projen-awscdkconstructlibrary) - AWS CDK construct library project.
 * [cdk8s-construct](https://github.com/projen/projen/blob/master/API.md#projen-constructlibrarycdk8s) - CDK8s construct library project.
+* [composite](https://github.com/projen/projen/blob/master/API.md#projen-compositeproject) - Creates a composite project.
 * [jsii](https://github.com/projen/projen/blob/master/API.md#projen-jsiiproject) - Multi-language jsii library project.
 * [nextjs](https://github.com/projen/projen/blob/master/API.md#projen-nextjsproject) - Next.js project without TypeScript.
 * [nextjs-ts](https://github.com/projen/projen/blob/master/API.md#projen-nextjstypescriptproject) - Next.js project with TypeScript.

diff --git a/src/composite-project.ts b/src/composite-project.ts
@@ -0,0 +1,86 @@
+import * as path from 'path';
+import { Component } from './component';
+import { Project } from './project';
+
+/**
+ * Options for `CompositeProject`.
+ */
+export interface CompositeProjectOptions {
+  /**
+   * Declaratively define sub-projects by their sub paths.
+   * @example
+   * [
+   *   {
+   *     path: path.join('packages', 'foo'),
+   *     project: new NodeProject({ name: 'foo' }),
+   *   },
+   *   ...
+   * ]
+   */
+  readonly projects?: CompositeProjectChild[];
+}
+
+/**
+ * Declares a sub-project of the composite project.
+ */
+export interface CompositeProjectChild {
+  /**
+   * Project subpath.
+   */
+  readonly path: string;
+
+  /**
+   * Projen project to synthesize in `path`.
+   */
+  readonly project: Project;
+}
+
+/**
+ * Creates a composite project.
+ */
+export class CompositeProject extends Project {
+  // Tracks which sub paths have already been added.
+  private readonly projects: Record<string, ProjectComponent>;
+
+  constructor(options?: CompositeProjectOptions) {
+    super();
+
+    this.projects = {};
+
+    // Add declaratively defined subprojects.
+    for (const subProject of options?.projects ?? []) {
+      this.addProject(subProject.path, subProject.project);
+    }
+  }
+
+  /**
+   * Adds a project as a sub-project at a sub path.
+   * @param subPath
+   * @param project
+   */
+  addProject(subPath: string, project: Project) {
+    if (this.projects[subPath]) {
+      throw new Error(`Cannot add project as the sub path ${subPath} is already in use`);
+    }
+
+    this.projects[subPath] = new ProjectComponent(this, {
+      path: subPath,
+      project: project,
+    });
+  }
+}
+
+/**
+ * Represent a project as a component in another project.
+ * @experimental
+ */
+class ProjectComponent extends Component {
+  constructor(project: Project, private readonly options: CompositeProjectChild) {
+    super(project);
+  }
+
+  synthesize(outdir: string) {
+    // Synths the project into a subdir given by `path`
+    this.options.project.synth(path.join(outdir, this.options.path));
+  }
+}
diff --git a/src/index.ts b/src/index.ts
@@ -2,6 +2,7 @@ export * from './awscdk-app-ts';
 export * from './awscdk-construct';
 export * from './cdk8s-construct';
 export * from './component';
+export * from './composite-project';
 export * from './construct-lib';
 export * from './dependabot';
 export * from './docker-compose';

diff --git a/test/__snapshots__/inventory.test.ts.snap b/test/__snapshots__/inventory.test.ts.snap
@@ -2994,6 +2994,28 @@ jest typescript tests and only if all tests pass, run the compiler.",
     "pjid": "cdk8s-construct",
     "typename": "ConstructLibraryCdk8s",
   },
+  Object {
+    "docs": "Creates a composite project.",
+    "docsurl": "https://github.com/projen/projen/blob/master/API.md#projen-compositeproject",
+    "fqn": "projen.CompositeProject",
+    "moduleName": "projen",
+    "options": Array [
+      Object {
+        "deprecated": false,
+        "docs": "Declaratively define sub-projects by their sub paths.",
+        "name": "projects",
+        "optional": true,
+        "parent": "CompositeProjectOptions",
+        "path": Array [
+          "projects",
+        ],
+        "switch": "projects",
+        "type": "unknown",
+      },
+    ],
+    "pjid": "composite",
+    "typename": "CompositeProject",
+  },
   Object {
     "docs": "Multi-language jsii library project.",
     "docsurl": "https://github.com/projen/projen/blob/master/API.md#projen-jsiiproject",

diff --git a/test/__snapshots__/new.test.ts.snap b/test/__snapshots__/new.test.ts.snap
@@ -272,6 +272,18 @@ project.synth();
 "
 `;
 
+exports[`projen new composite 1`] = `
+"const { CompositeProject } = require('projen');
+
+const project = new CompositeProject({
+  /* CompositeProjectOptions */
+  // projects: undefined,  /* Declaratively define sub-projects by their sub paths. */
+});
+
+project.synth();
+"
+`;
+
 exports[`projen new jsii 1`] = `
 "const { JsiiProject } = require('projen');
 

diff --git a/test/composite-project.test.ts b/test/composite-project.test.ts
@@ -0,0 +1,66 @@
+import * as path from 'path';
+import * as fs from 'fs-extra';
+import { NodeProject, Project, CompositeProject } from '../src';
+import * as logging from '../src/logging';
+
+logging.disable();
+
+let tempDir: string;
+beforeEach(() => {
+  tempDir = fs.mkdtempSync(path.join(__dirname, 'tmp.subdir'));
+});
+
+afterEach(() => {
+  if (tempDir) {
+    fs.removeSync(tempDir);
+  }
+});
+
+test('composing projects declaratively', () => {
+  const comp = new CompositeProject({
+    projects: [
+      {
+        path: path.join('packages', 'foo'),
+        project: new Project(),
+      },
+    ],
+  });
+
+  comp.synth(tempDir);
+
+  // THEN
+  expect(fs.existsSync(path.join(tempDir, 'packages', 'foo', '.gitignore'))).toBeTruthy();
+});
+
+test('composing projects synthesizes to subdirs', () => {
+  // GIVEN
+  const comp = new CompositeProject();
+
+  // WHEN
+  comp.addProject(path.join('packages', 'foo'), new NodeProject({ name: 'foo' }));
+  comp.addProject(path.join('packages', 'bar'), new NodeProject({ name: 'bar' }));
+
+  comp.synth(tempDir);
+
+  // THEN
+  expect(fs.pathExistsSync(path.join(tempDir, 'README.md')));
+  expect(fs.readJSONSync(path.join(tempDir, 'packages', 'foo', 'package.json')))
+    .toEqual(expect.objectContaining({
+      name: 'foo',
+    }));
+  expect(fs.readJSONSync(path.join(tempDir, 'packages', 'bar', 'package.json')))
+    .toEqual(expect.objectContaining({
+      name: 'bar',
+    }));
+});
+
+test('errors when paths overlap', () => {
+  // GIVEN
+  const comp = new CompositeProject();
+  comp.addProject(path.join('packages', 'foo'), new NodeProject({ name: 'foo' }));
+
+  // WHEN/THEN
+  expect(() => {
+    comp.addProject(path.join('packages', 'foo'), new NodeProject({ name: 'bar' }));
+  }).toThrowError(/foo.*already in use/i);
+});