Run pub tests against older versions of barback.

sdk/lib/_internal/pub/test/transformer/exclusion/works_on_transformer_group_test.dart

Index: sdk/lib/_internal/pub/test/transformer/exclusion/works_on_transformer_group_test.dart
diff --git a/sdk/lib/_internal/pub/test/transformer/exclusion/works_on_transformer_group_test.dart b/sdk/lib/_internal/pub/test/transformer/exclusion/works_on_transformer_group_test.dart
index d18fd56dd413b3cc9156e7539b19491a240a2a80..27fd71cbe70f577b9ed6cd0c47c4cf39ef8fa14a 100644
--- a/sdk/lib/_internal/pub/test/transformer/exclusion/works_on_transformer_group_test.dart
+++ b/sdk/lib/_internal/pub/test/transformer/exclusion/works_on_transformer_group_test.dart
@@ -22,36 +22,38 @@ class RewriteGroup implements TransformerGroup {
 
 main() {
   initConfig();
-  integration("works on a transformer group", () {
-    d.dir(appPath, [
-      d.pubspec({
-        "name": "myapp",
-        "transformers": [
-          {
-            "myapp/src/group": {
-              "\$include": ["web/a.txt", "web/b.txt"],
-              "\$exclude": "web/a.txt"
+  withBarbackVersions("any", () {
+    integration("works on a transformer group", () {
+      d.dir(appPath, [
+        d.pubspec({
+          "name": "myapp",
+          "transformers": [
+            {
+              "myapp/src/group": {
+                "\$include": ["web/a.txt", "web/b.txt"],
+                "\$exclude": "web/a.txt"
+              }
             }
-          }
-        ]
-      }),
-      d.dir("lib", [d.dir("src", [
-        d.file("transformer.dart", REWRITE_TRANSFORMER),
-        d.file("group.dart", GROUP)
-      ])]),
-      d.dir("web", [
-        d.file("a.txt", "a.txt"),
-        d.file("b.txt", "b.txt"),
-        d.file("c.txt", "c.txt")
-      ])
-    ]).create();
-
-    createLockFile('myapp', pkg: ['barback']);
-
-    pubServe();
-    requestShould404("a.out");
-    requestShouldSucceed("b.out", "b.txt.out");
-    requestShould404("c.out");
-    endPubServe();
+          ]
+        }),
+        d.dir("lib", [d.dir("src", [
+          d.file("transformer.dart", REWRITE_TRANSFORMER),
+          d.file("group.dart", GROUP)
+        ])]),
+        d.dir("web", [
+          d.file("a.txt", "a.txt"),
+          d.file("b.txt", "b.txt"),
+          d.file("c.txt", "c.txt")
+        ])
+      ]).create();
+
+      createLockFile('myapp', pkg: ['barback']);
+
+      pubServe();
+      requestShould404("a.out");
+      requestShouldSucceed("b.out", "b.txt.out");
+      requestShould404("c.out");
+      endPubServe();
+    });
   });
 }