Add support for build_extensions configuration of builders producing multiple files (#647)

Allow lists or single strings in the options.

Author: d-markey

source_gen/CHANGELOG.md

@@ -1,3 +1,8 @@
+## 1.3.0
+
+* Add support for `build_extensions` configuration of builders producing multiple files. Eg:
+  `build_extensions: { '.dart': ['.stub.dart', '.web.dart', '.vm.dart'] }`
+
 ## 1.2.7
 
 * Update the value of the pubspec `repository` field.

source_gen/lib/src/utils.dart

@@ -176,7 +176,11 @@ Map<String, List<String>> validatedBuildExtensionsFrom(
   Map<String, List<String>> defaultExtensions,
 ) {
   final extensionsOption = optionsMap?.remove('build_extensions');
-  if (extensionsOption == null) return defaultExtensions;
+  if (extensionsOption == null) {
+    // defaultExtensions are provided by the builder author, not the end user.
+    // It should be safe to skip validation.
+    return defaultExtensions;
+  }
 
   if (extensionsOption is! Map) {
     throw ArgumentError(
@@ -195,15 +199,19 @@ Map<String, List<String>> validatedBuildExtensionsFrom(
       );
     }
 
-    final output = entry.value;
-    if (output is! String || !output.endsWith('.dart')) {
-      throw ArgumentError(
-        'Invalid output extension `$output`. It should be a '
-        'string ending with `.dart`',
-      );
+    final output = (entry.value is List) ? entry.value as List : [entry.value];
+
+    for (var i = 0; i < output.length; i++) {
+      final o = output[i];
+      if (o is! String || (i == 0 && !o.endsWith('.dart'))) {
+        throw ArgumentError(
+          'Invalid output extension `${entry.value}`. It should be a string '
+          'or a list of strings with the first ending with `.dart`',
+        );
+      }
     }
 
-    result[input] = [output];
+    result[input] = output.cast<String>().toList();
   }
 
   if (result.isEmpty) {

source_gen/pubspec.yaml

@@ -1,5 +1,5 @@
 name: source_gen
-version: 1.2.7
+version: 1.3.0
 description: >-
   Source code generation builders and utilities for the Dart build system
 repository: https://github.com/dart-lang/source_gen/tree/master/source_gen

source_gen/test/utils_test.dart

@@ -46,14 +46,42 @@ void main() {
 
   group('validatedBuildExtensionsFrom', () {
     test('no option given -> return defaultBuildExtension ', () {
-      final buildEtension = validatedBuildExtensionsFrom({}, {
+      final buildExtension = validatedBuildExtensionsFrom({}, {
         '.dart': ['.foo.dart'],
       });
-      expect(buildEtension, {
+      expect(buildExtension, {
         '.dart': ['.foo.dart'],
       });
     });
 
+    test('allows multiple output extensions', () {
+      final buildExtensions = validatedBuildExtensionsFrom(
+        {
+          'build_extensions': {
+            '.dart': ['.g.dart', '.h.dart']
+          }
+        },
+        {},
+      );
+      expect(buildExtensions, {
+        '.dart': ['.g.dart', '.h.dart'],
+      });
+    });
+
+    test('allows multiple output extensions of various types ', () {
+      final buildExtensions = validatedBuildExtensionsFrom(
+        {
+          'build_extensions': {
+            '.dart': ['.g.dart', '.swagger.json']
+          }
+        },
+        {},
+      );
+      expect(buildExtensions, {
+        '.dart': ['.g.dart', '.swagger.json'],
+      });
+    });
+
     test("disallows options that aren't a map", () {
       expect(
         () => validatedBuildExtensionsFrom({'build_extensions': 'foo'}, {}),
@@ -104,8 +132,28 @@ void main() {
           isArgumentError.having(
             (e) => e.message,
             'message',
-            'Invalid output extension `.out`. It should be a string ending '
-                'with `.dart`',
+            'Invalid output extension `.out`. It should be a string or a list '
+                'of strings with the first ending with `.dart`',
+          ),
+        ),
+      );
+
+      expect(
+        () => validatedBuildExtensionsFrom(
+          {
+            'build_extensions': {
+              '.dart': ['.out', '.g.dart']
+            }
+          },
+          {},
+        ),
+        throwsA(
+          isArgumentError.having(
+            (e) => e.message,
+            'message',
+            'Invalid output extension `[.out, .g.dart]`. It should be a '
+                'string or a list of strings with the first ending with '
+                '`.dart`',
           ),
         ),
       );