diff --git a/pkg/tracing/lightstep/lightstep_test.go b/pkg/tracing/lightstep/lightstep_test.go
new file mode 100644
index 00000000000..2e688c19f38
--- /dev/null
+++ b/pkg/tracing/lightstep/lightstep_test.go
@@ -0,0 +1,60 @@
+// Copyright (c) The Thanos Authors.
+// Licensed under the Apache License 2.0.
+
+package lightstep
+
+import (
+	"os"
+	"testing"
+
+	"github.com/thanos-io/thanos/pkg/testutil"
+
+	"github.com/opentracing/opentracing-go"
+)
+
+func TestParseTags(t *testing.T) {
+	type testData struct {
+		input          string
+		description    string
+		expectedOutput opentracing.Tags
+	}
+
+	testingData := []testData{
+		{
+			description:    `A very simple case, key "foo" and value "bar"`,
+			input:          "foo=bar",
+			expectedOutput: opentracing.Tags{"foo": "bar"},
+		},
+		{
+			description:    `A simple case multiple keys, keys ["foo", "bar"] and values ["foo", "bar"]`,
+			input:          "foo=foo,bar=bar",
+			expectedOutput: opentracing.Tags{"foo": "foo", "bar": "bar"},
+		},
+		{
+			description:    `A case with empty environment variable, key "foo" and value ""`,
+			input:          "foo=${TEST:}",
+			expectedOutput: opentracing.Tags{"foo": ""},
+		},
+		{
+			description:    `A case with empty environment variable, key "foo" and value ""`,
+			input:          "foo=${TEST:}",
+			expectedOutput: opentracing.Tags{"foo": ""},
+		},
+		{
+			description:    `A case with default environment variable, key "foo" and value "default"`,
+			input:          "foo=${TEST:default}",
+			expectedOutput: opentracing.Tags{"foo": "default"},
+		},
+		{
+			description:    `A case with real environment variable, key "foo" and value "env-bar"`,
+			input:          "foo=${_TEST_PARSE_TAGS:default}",
+			expectedOutput: opentracing.Tags{"foo": "env-bar"},
+		},
+	}
+
+	os.Setenv("_TEST_PARSE_TAGS", "env-bar")
+	for _, test := range testingData {
+		t.Logf("testing %s\n", test.description)
+		testutil.Equals(t, test.expectedOutput, parseTags(test.input))
+	}
+}