Add test for applying headers

Signed-off-by: Christian Haudum <christian.haudum@gmail.com>

pkg/canary/reader/reader_test.go

@@ -0,0 +1,52 @@
+package reader
+
+import (
+	"encoding/base64"
+	"net/http"
+	"testing"
+
+	"github.com/stretchr/testify/require"
+)
+
+func TestApplyHeaders(t *testing.T) {
+	reader := &Reader{
+		user:     "user",
+		pass:     "pass",
+		tenantID: "tenant",
+		actor:    "actor",
+	}
+
+	t.Run("apply headers to existing request", func(t *testing.T) {
+		req, _ := http.NewRequest(http.MethodGet, "/", nil)
+		header := reader.ApplyHeaders(req)
+		require.Equal(t, "tenant", req.Header.Get("X-Scope-OrgID"))
+		require.Equal(t, "actor", req.Header.Get("X-Loki-Actor-Path"))
+		require.Equal(t, "loki-canary/", req.Header.Get("User-Agent"))
+
+		auth := reader.user + ":" + reader.pass
+		require.Equal(t, "Basic "+base64.StdEncoding.EncodeToString([]byte(auth)), req.Header.Get("Authorization"))
+
+		require.Equal(t, req.Header, header)
+	})
+
+	t.Run("apply headers to nil request", func(t *testing.T) {
+		header := reader.ApplyHeaders(nil)
+		require.Equal(t, "tenant", header.Get("X-Scope-OrgID"))
+		require.Equal(t, "actor", header.Get("X-Loki-Actor-Path"))
+		require.Equal(t, "loki-canary/", header.Get("User-Agent"))
+
+		auth := reader.user + ":" + reader.pass
+		require.Equal(t, "Basic "+base64.StdEncoding.EncodeToString([]byte(auth)), header.Get("Authorization"))
+	})
+
+	t.Run("only apply headers for existing fields", func(t *testing.T) {
+		reader := &Reader{}
+		header := reader.ApplyHeaders(nil)
+		keys := []string{}
+		for k := range header {
+			keys = append(keys, k)
+		}
+		require.Equal(t, []string{"User-Agent"}, keys)
+	})
+
+}