diff --git a/pkg/tsdb/prometheus/prometheus_test.go b/pkg/tsdb/prometheus/prometheus_test.go
new file mode 100644
index 00000000000..d5ee22300a7
--- /dev/null
+++ b/pkg/tsdb/prometheus/prometheus_test.go
@@ -0,0 +1,103 @@
+package prometheus
+
+import (
+	"context"
+	"net/http"
+	"testing"
+	"time"
+
+	"github.com/grafana/grafana-plugin-sdk-go/backend"
+	"github.com/grafana/grafana-plugin-sdk-go/backend/datasource"
+	sdkHttpClient "github.com/grafana/grafana-plugin-sdk-go/backend/httpclient"
+	"github.com/grafana/grafana/pkg/infra/httpclient"
+	"github.com/grafana/grafana/pkg/services/featuremgmt"
+	"github.com/grafana/grafana/pkg/setting"
+	"github.com/stretchr/testify/require"
+)
+
+type fakeSender struct{}
+
+func (sender *fakeSender) Send(resp *backend.CallResourceResponse) error {
+	return nil
+}
+
+type fakeRoundtripper struct{}
+
+func (rt *fakeRoundtripper) RoundTrip(req *http.Request) (*http.Response, error) {
+	return &http.Response{
+		Status:        "200",
+		StatusCode:    200,
+		Header:        nil,
+		Body:          nil,
+		ContentLength: 0,
+	}, nil
+}
+
+type fakeHTTPClientProvider struct {
+	httpclient.Provider
+	opts []sdkHttpClient.Options
+}
+
+func (provider *fakeHTTPClientProvider) New(opts ...sdkHttpClient.Options) (*http.Client, error) {
+	client := &http.Client{}
+	client.Transport = &fakeRoundtripper{}
+	provider.opts = opts
+	return client, nil
+}
+
+func TestClient(t *testing.T) {
+	t.Run("Service", func(t *testing.T) {
+		t.Run("CallResource", func(t *testing.T) {
+			t.Run("Adds correct headers", func(t *testing.T) {
+				// Not a great test as right now we put the headers form request and custom headers into a client during
+				// it's creation and then relly on sdk middleware to add it to the request later on. This is hard to
+				// test so for now this just checks if the correct headers are passed to the http client not whether
+				// they are actually added to the request.
+
+				httpProvider := &fakeHTTPClientProvider{}
+				service := &Service{
+					im: datasource.NewInstanceManager(newInstanceSettings(httpProvider, &setting.Cfg{}, &featuremgmt.FeatureManager{}, nil)),
+				}
+
+				req := &backend.CallResourceRequest{
+					PluginContext: backend.PluginContext{
+						OrgID:               0,
+						PluginID:            "prometheus",
+						User:                nil,
+						AppInstanceSettings: nil,
+						DataSourceInstanceSettings: &backend.DataSourceInstanceSettings{
+							ID:               0,
+							UID:              "",
+							Type:             "prometheus",
+							Name:             "test-prom",
+							URL:              "http://localhost:9090",
+							User:             "",
+							Database:         "",
+							BasicAuthEnabled: true,
+							BasicAuthUser:    "admin",
+							// Custom headers from data source configuration
+							JSONData: []byte("{\"httpHeaderName1\":\"x-tenant-id\"}"),
+							DecryptedSecureJSONData: map[string]string{
+								"httpHeaderValue1": "0987",
+							},
+							Updated: time.Time{},
+						},
+					},
+					Path:   "/api/v1/series",
+					Method: http.MethodPost,
+					URL:    "/api/v1/series",
+					// Header in the request itself sent from the browser
+					Headers: map[string][]string{
+						"foo": {"bar"},
+					},
+					Body: []byte("match%5B%5D: ALERTS\nstart: 1655271408\nend: 1655293008"),
+				}
+
+				sender := &fakeSender{}
+				err := service.CallResource(context.Background(), req, sender)
+				require.NoError(t, err)
+				require.Equal(t, map[string]string{"X-Tenant-Id": "0987", "foo": "bar"}, httpProvider.opts[0].Headers)
+			})
+		})
+	})
+}
diff --git a/pkg/tsdb/prometheus/resource/resource.go b/pkg/tsdb/prometheus/resource/resource.go
index c6479f68185..4c58be8d5ce 100644
--- a/pkg/tsdb/prometheus/resource/resource.go
+++ b/pkg/tsdb/prometheus/resource/resource.go
@@ -81,8 +81,6 @@ func New(
 		return nil, fmt.Errorf("error reading settings: %w", err)
 	}
 
-	p := client.NewProvider(settings, jsonData, httpClientProvider, cfg, features, plog)
-
 	customHeaders := make(map[string]string)
 	var jsonDataMap map[string]interface{}
 
@@ -113,7 +111,7 @@ func New(
 
 	return &Resource{
 		log:           plog,
-		provider:      p,
+		provider:      client.NewProvider(settings, jsonData, httpClientProvider, cfg, features, plog),
 		customHeaders: customHeaders,
 	}, nil
 }