Support JSON output for pub build.

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

Index: sdk/lib/_internal/pub/test/build/does_not_allow_args_with_all_test.dart
diff --git a/sdk/lib/_internal/pub/test/build/does_not_allow_args_with_all_test.dart b/sdk/lib/_internal/pub/test/build/does_not_allow_args_with_all_test.dart
index 5cd9dcf972bbdf0837a6e0a33f10cf06e3c0658c..3f3868cea3d8fbae7114f541c59d5da8c64311b9 100644
--- a/sdk/lib/_internal/pub/test/build/does_not_allow_args_with_all_test.dart
+++ b/sdk/lib/_internal/pub/test/build/does_not_allow_args_with_all_test.dart
@@ -15,7 +15,31 @@ main() {
     ]).create();
 
     schedulePub(args: ["build", "example", "--all"],
-        error: 'Build directory names are not allowed if "--all" is passed.',
+        error: '''
+            Build directory names are not allowed if "--all" is passed.
+
+            Usage: pub build [options]
+            -h, --help      Print usage information for this command.
+                --format    How output should be displayed.
+                            [text (default), json]
+
+                --mode      Mode to run transformers in.
+                            (defaults to "release")
+
+                --all       Build all buildable directories.''',
         exitCode: exit_codes.USAGE);
   });
+
+  integration("does not allow directory names with --all with JSON output", () {
+    d.dir(appPath, [
+      d.appPubspec()
+    ]).create();
+
+    schedulePub(args: ["build", "example", "--all", "--format", "json"],
+        outputJson: {
+          "error": 'Build directory names are not allowed if "--all" is passed.'
+        },
+        exitCode: exit_codes.USAGE);
+  });
+
 }