Non-modular templates (#2368)

* Support non-modular templates

* Update docs

* Add tests

* Add fixtures

* Create eight-rules-drop.md

.changeset/eight-rules-drop.md

@@ -0,0 +1,5 @@
+---
+"modular-scripts": minor
+---
+
+Support non-modular templates

__fixtures__/templates/modular-template-non-modular/CHANGELOG.md

@@ -0,0 +1 @@
+# Test File

__fixtures__/templates/modular-template-non-modular/README.md

@@ -0,0 +1 @@
+# This is a README placeholder for this template fixture

__fixtures__/templates/modular-template-non-modular/package.json

@@ -0,0 +1,14 @@
+{
+  "name": "modular-template-non-modular",
+  "version": "1.1.0",
+  "exports": {
+    "./package.json": "./package.json"
+  },
+  "modular": {
+    "type": "template"
+  },
+  "license": "Apache-2.0",
+  "files": [
+    "src"
+  ]
+}

__fixtures__/templates/modular-template-non-modular/src/index.ts

@@ -0,0 +1 @@
+console.log('I am a non-modular template');

docs/how-to/create-template.md

@@ -15,7 +15,9 @@ To convert the package into a template, make the following changes to the
 package's package.json:
 
 - Change `modular.type` field to `"template"`
-- Add `modular.templateType` with the desired target package type
+- Optionally add `modular.templateType` with the desired target package type. If
+  `modular.templateType` is not present, the target package will not have a
+  `modular` field in its `packages.json`.
 
 Example configuration for a template that generates `esm-view`s.
 

docs/package-types/template.md

@@ -96,6 +96,12 @@ is passed to `modular add`:
 }
 ```
 
+## Templates for non-Modular packages
+
+If `modular.templateType` is not set in the template package, the target package
+will not have a `modular` field at all. This is useful to create non-Modular
+templates which have their own configuration and scripts.
+
 ## Template contents and interpolation
 
 All the files contained in the template package (optionally filtered by the

packages/modular-scripts/src/__tests__/addPackage.test.ts

@@ -25,6 +25,10 @@ const noFilterTemplatePath = path.join(
   templatesPath,
   'modular-template-no-filter',
 );
+const nonModularTemplatePath = path.join(
+  templatesPath,
+  'modular-template-non-modular',
+);
 
 // Temporary test context paths set by createTempModularRepoWithTemplate()
 let tempModularRepo: string;
@@ -182,6 +186,28 @@ describe('When adding a module from a template without a files filter', () => {
   });
 });
 
+describe('When adding a module from a template with a target non-modular workspace', () => {
+  let newModulePath: string;
+  beforeAll(async () => {
+    createTempModularRepoWithTemplate(nonModularTemplatePath);
+    setupMocks(tempModularRepo);
+    newModulePath = path.join(tempPackagesPath, 'non-modular-workspace');
+    await addPackageForTests('non-modular-workspace', 'non-modular');
+  });
+
+  it('generates the package.json', async () => {
+    // Expect name to be as set by command, and type as set by template
+    expect(await fs.readJSON(path.join(newModulePath, 'package.json')))
+      .toMatchInlineSnapshot(`
+        {
+          "name": "non-modular-workspace",
+          "private": false,
+          "version": "1.0.0",
+        }
+      `);
+  });
+});
+
 describe('When adding a module from a template with a files filter', () => {
   let newModulePath: string;
   beforeAll(async () => {

packages/modular-scripts/src/addPackage.ts

@@ -197,14 +197,18 @@ async function addPackage({
   }
 
   const modularTemplateType = modularTemplatePackageJson?.modular
-    ?.templateType as string;
+    ?.templateType as string | undefined;
+
   if (
-    !['app', 'esm-view', 'view', 'source', 'package'].includes(
-      modularTemplateType,
+    !(
+      modularTemplateType === undefined ||
+      ['app', 'esm-view', 'view', 'source', 'package'].includes(
+        modularTemplateType,
+      )
     )
   ) {
     throw new Error(
-      `${templateName} has modular type: ${modularTemplateType}, which does not exist, please use update this template`,
+      `${templateName} has modular type: ${modularTemplateType}, which does not exist, please update this template`,
     );
   }
 
@@ -243,9 +247,11 @@ async function addPackage({
     {
       name,
       private: modularTemplateType === 'app',
-      modular: {
-        type: modularTemplateType,
-      },
+      modular: modularTemplateType
+        ? {
+            type: modularTemplateType,
+          }
+        : undefined,
       main: modularTemplatePackageJson?.main,
       dependencies: modularTemplatePackageJson?.dependencies,
       version: '1.0.0',