[CQ] [linter] unify test package dependency creation

As previously implemented, we were creating a new package config builder if we wanted a dependency on `package:reflective_test_loader` which would clobber any previously contributed dependencies. Beside being confusing, this means that you can't have tests that require `package:reflective_test_loader` and any other dependency (such as, for example, `package:meta`).

This fixes that.


Change-Id: Ia16b6c66f6a93a01f8dfa67c871877692414e03b
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/412801
Auto-Submit: Phil Quitslund <[email protected]>
Reviewed-by: Brian Wilkerson <[email protected]>
Commit-Queue: Phil Quitslund <[email protected]>

Author: pq

pkg/linter/test/rule_test_support.dart

@@ -177,6 +177,8 @@ class PubPackageResolutionTest extends _ContextResolutionTest {
 
   bool get addMetaPackageDep => false;
 
+  bool get addReflectiveTestLoaderPackageDep => false;
+
   bool get dumpAstOnFailures => true;
 
   List<String> get experiments => experimentsForTests;
@@ -199,25 +201,6 @@ class PubPackageResolutionTest extends _ContextResolutionTest {
   @override
   List<String> get _collectionIncludedPaths => [workspaceRootPath];
 
-  void addReflectiveTestLoaderDep() {
-    // TODO(pq): consider mopcing this into `writeTestPackageConfig`
-    var testReflectiveLoaderPath = '$workspaceRootPath/test_reflective_loader';
-    var packageConfigBuilder = PackageConfigFileBuilder();
-    packageConfigBuilder.add(
-      name: 'test_reflective_loader',
-      rootPath: testReflectiveLoaderPath,
-    );
-    writeTestPackageConfig(packageConfigBuilder);
-    newFile('$testReflectiveLoaderPath/lib/test_reflective_loader.dart', r'''
-library test_reflective_loader;
-
-const Object reflectiveTest = _ReflectiveTest();
-class _ReflectiveTest {
-  const _ReflectiveTest();
-}
-''');
-  }
-
   /// Asserts that the number of diagnostics reported in [content] matches the
   /// number of [expectedDiagnostics] and that they have the expected error
   /// descriptions and locations.
@@ -349,6 +332,23 @@ class _ReflectiveTest {
       configCopy.add(name: 'meta', rootPath: metaPath);
     }
 
+    if (addReflectiveTestLoaderPackageDep) {
+      var testReflectiveLoaderPath =
+          '$workspaceRootPath/test_reflective_loader';
+      newFile('$testReflectiveLoaderPath/lib/test_reflective_loader.dart', r'''
+library test_reflective_loader;
+
+const Object reflectiveTest = _ReflectiveTest();
+class _ReflectiveTest {
+  const _ReflectiveTest();
+}
+''');
+      configCopy.add(
+        name: 'test_reflective_loader',
+        rootPath: testReflectiveLoaderPath,
+      );
+    }
+
     var path = '$testPackageRootPath/.dart_tool/package_config.json';
     writePackageConfig(path, configCopy);
   }

pkg/linter/test/rules/strict_top_level_inference_test.dart

@@ -15,6 +15,9 @@ void main() {
 
 @reflectiveTest
 class StrictTopLevelInferenceTest extends LintRuleTest {
+  @override
+  bool get addReflectiveTestLoaderPackageDep => true;
+
   @override
   List<ErrorCode> get ignoredErrorCodes => [
     WarningCode.UNUSED_ELEMENT,
@@ -684,7 +687,6 @@ void f() {
   }
 
   test_reflectiveTest_nonTest() async {
-    addReflectiveTestLoaderDep();
     await assertDiagnostics(
       r'''
 import 'package:test_reflective_loader/test_reflective_loader.dart';
@@ -699,7 +701,6 @@ class ReflectiveTest {
   }
 
   test_reflectiveTest_soloTest() async {
-    addReflectiveTestLoaderDep();
     await assertNoDiagnostics(r'''
 import 'package:test_reflective_loader/test_reflective_loader.dart';
 
@@ -711,7 +712,6 @@ class ReflectiveTest {
   }
 
   test_reflectiveTest_test() async {
-    addReflectiveTestLoaderDep();
     await assertNoDiagnostics(r'''
 import 'package:test_reflective_loader/test_reflective_loader.dart';
 

pkg/linter/test/rules/unreachable_from_main_test.dart

@@ -17,6 +17,9 @@ class UnreachableFromMainTest extends LintRuleTest {
   @override
   bool get addMetaPackageDep => true;
 
+  @override
+  bool get addReflectiveTestLoaderPackageDep => true;
+
   @override
   String get lintRule => LintNames.unreachable_from_main;
 
@@ -798,7 +801,6 @@ class C {
   }
 
   test_constructor_reachableViaTestReflectiveLoader() async {
-    addReflectiveTestLoaderDep();
     await assertNoDiagnostics(r'''
 import 'package:test_reflective_loader/test_reflective_loader.dart';