Run pub tests against older versions of barback.

sdk/lib/_internal/pub/test/build/outputs_error_to_json_test.dart

Index: sdk/lib/_internal/pub/test/build/outputs_error_to_json_test.dart
diff --git a/sdk/lib/_internal/pub/test/build/outputs_error_to_json_test.dart b/sdk/lib/_internal/pub/test/build/outputs_error_to_json_test.dart
index 074690a26238e598397012138a6fc26885f5e48f..bbd31fdddcd2c787d3d08791ac4e2b4d8aadfc85 100644
--- a/sdk/lib/_internal/pub/test/build/outputs_error_to_json_test.dart
+++ b/sdk/lib/_internal/pub/test/build/outputs_error_to_json_test.dart
@@ -26,37 +26,39 @@ class RewriteTransformer extends Transformer {
 
 main() {
   initConfig();
-  integration("outputs error to JSON in a failed build", () {
-    // Loading transformers takes several seconds, so make sure we don't
-    // timeout.
-    currentSchedule.timeout *= 2;
-
-    d.dir(appPath, [
-      d.pubspec({
-        "name": "myapp",
-        "transformers": ["myapp"]
-      }),
-      d.dir("lib", [
-        d.file("transformer.dart", TRANSFORMER)
-      ]),
-      d.dir("web", [
-        d.file("foo.txt", "foo")
-      ])
-    ]).create();
-
-    createLockFile('myapp', pkg: ['barback']);
-
-    schedulePub(args: ["build", "--format", "json"],
-        outputJson: {
-          "buildResult": "failure",
-          "errors": [
-            {
-              "error": startsWith(
-                  "Transform Rewrite on myapp|web/foo.txt threw error: oh no!")
-            }
-          ],
-          "log": []
-        },
-        exitCode: exit_codes.DATA);
+  withBarbackVersions("any", () {
+    integration("outputs error to JSON in a failed build", () {
+      // Loading transformers takes several seconds, so make sure we don't
+      // timeout.
+      currentSchedule.timeout *= 2;
+
+      d.dir(appPath, [
+        d.pubspec({
+          "name": "myapp",
+          "transformers": ["myapp"]
+        }),
+        d.dir("lib", [
+          d.file("transformer.dart", TRANSFORMER)
+        ]),
+        d.dir("web", [
+          d.file("foo.txt", "foo")
+        ])
+      ]).create();
+
+      createLockFile('myapp', pkg: ['barback']);
+
+      schedulePub(args: ["build", "--format", "json"],
+          outputJson: {
+            "buildResult": "failure",
+            "errors": [
+              {
+                "error": startsWith("Transform Rewrite on myapp|web/foo.txt "
+                    "threw error: oh no!")
+              }
+            ],
+            "log": []
+          },
+          exitCode: exit_codes.DATA);
+    });
   });
 }