diff --git a/src/x/net/http/errors_test.go b/src/x/net/http/errors_test.go
new file mode 100644
index 0000000000..4bd5ecf46d
--- /dev/null
+++ b/src/x/net/http/errors_test.go
@@ -0,0 +1,54 @@
+// Copyright (c) 2018 Uber Technologies, Inc.
+//
+// Permission is hereby granted, free of charge, to any person obtaining a copy
+// of this software and associated documentation files (the "Software"), to deal
+// in the Software without restriction, including without limitation the rights
+// to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+// copies of the Software, and to permit persons to whom the Software is
+// furnished to do so, subject to the following conditions:
+//
+// The above copyright notice and this permission notice shall be included in
+// all copies or substantial portions of the Software.
+//
+// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+// THE SOFTWARE.
+
+package xhttp
+
+import (
+	"fmt"
+	"testing"
+
+	"github.com/stretchr/testify/require"
+
+	xerrors "github.com/m3db/m3/src/x/errors"
+)
+
+func TestIsClientError(t *testing.T) {
+	tests := []struct {
+		err      error
+		expected bool
+	}{
+		{NewError(fmt.Errorf("xhttp.Error(400)"), 400), true},
+		{NewError(fmt.Errorf("xhttp.Error(499)"), 499), true},
+		{xerrors.NewInvalidParamsError(fmt.Errorf("InvalidParamsError")), true},
+		{xerrors.NewRetryableError(xerrors.NewInvalidParamsError(
+			fmt.Errorf("InvalidParamsError insde RetyrableError"))), true},
+
+		{NewError(fmt.Errorf("xhttp.Error(399)"), 399), false},
+		{NewError(fmt.Errorf("xhttp.Error(500)"), 500), false},
+		{xerrors.NewRetryableError(fmt.Errorf("any error inside RetryableError")), false},
+		{fmt.Errorf("any error"), false},
+	}
+
+	for _, tt := range tests {
+		t.Run(tt.err.Error(), func(t *testing.T) {
+			require.Equal(t, tt.expected, IsClientError(tt.err))
+		})
+	}
+}