Allow test runners to wrap contexts

Let the test runners choose the namespaces and
wrap the contexts. This allows the test suite to create
multiple contexts without worrying about namespacing
or leasing in the contexts.

Signed-off-by: Derek McGowan <derek@mcgstyle.net>

content/testsuite/testsuite.go

@@ -14,7 +14,6 @@ import (
 	"time"
 
 	"github.com/containerd/containerd/content"
-	"github.com/containerd/containerd/namespaces"
 	"github.com/containerd/containerd/testutil"
 	"github.com/gotestyourself/gotestyourself/assert"
 	digest "github.com/opencontainers/go-digest"
@@ -34,9 +33,33 @@ func ContentSuite(t *testing.T, name string, storeFn func(ctx context.Context, r
 	t.Run("Labels", makeTest(t, name, storeFn, checkLabels))
 }
 
+// ContextWrapper is used to decorate new context used inside the test
+// before using the context on the content store.
+// This can be used to support leasing and multiple namespaces tests.
+type ContextWrapper func(ctx context.Context) (context.Context, func() error, error)
+
+type wrapperKey struct{}
+
+// SetContextWrapper sets the wrapper on the context for deriving
+// new test contexts from the context.
+func SetContextWrapper(ctx context.Context, w ContextWrapper) context.Context {
+	return context.WithValue(ctx, wrapperKey{}, w)
+}
+
+type nameKey struct{}
+
+// Name gets the test name from the context
+func Name(ctx context.Context) string {
+	name, ok := ctx.Value(nameKey{}).(string)
+	if !ok {
+		return ""
+	}
+	return name
+}
+
 func makeTest(t *testing.T, name string, storeFn func(ctx context.Context, root string) (context.Context, content.Store, func() error, error), fn func(ctx context.Context, t *testing.T, cs content.Store)) func(t *testing.T) {
 	return func(t *testing.T) {
-		ctx := namespaces.WithNamespace(context.Background(), name)
+		ctx := context.WithValue(context.Background(), nameKey{}, name)
 
 		tmpDir, err := ioutil.TempDir("", "content-suite-"+name+"-")
 		if err != nil {
@@ -54,6 +77,20 @@ func makeTest(t *testing.T, name string, storeFn func(ctx context.Context, root
 			}
 		}()
 
+		w, ok := ctx.Value(wrapperKey{}).(ContextWrapper)
+		if ok {
+			var done func() error
+			ctx, done, err = w(ctx)
+			if err != nil {
+				t.Fatalf("Error wrapping context: %+v", err)
+			}
+			defer func() {
+				if err := done(); err != nil && !t.Failed() {
+					t.Fatalf("Wrapper release failed: %+v", err)
+				}
+			}()
+		}
+
 		defer testutil.DumpDirOnFailure(t, tmpDir)
 		fn(ctx, t, cs)
 	}