PMM-13078 List available client versions (#3077)

* PMM-13078 List available client versions

* PMM-13078 add unit tests

* PMM-13078 add an API test

* PMM-13078 follow up on PR review comments

* PMM-13078 address review comments

Dockerfile

@@ -8,4 +8,5 @@ RUN export GOPATH=$(go env GOPATH) && \
 COPY . $GOPATH/src/github.com/percona/pmm/
 WORKDIR $GOPATH/src/github.com/percona/pmm/api-tests/
 
-CMD make init run-race
+CMD ["make", "init", "run-race"]
+

api-tests/management/services/agent_test.go

@@ -0,0 +1,46 @@
+// Copyright (C) 2023 Percona LLC
+//
+// This program is free software: you can redistribute it and/or modify
+// it under the terms of the GNU Affero General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+//
+// This program is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+// GNU Affero General Public License for more details.
+//
+// You should have received a copy of the GNU Affero General Public License
+// along with this program. If not, see <https://www.gnu.org/licenses/>.
+
+package services
+
+import (
+	"context"
+	"testing"
+	"time"
+
+	"github.com/AlekSi/pointer"
+	"github.com/stretchr/testify/require"
+
+	pmmapitests "github.com/percona/pmm/api-tests"
+	"github.com/percona/pmm/api/management/v1/json/client"
+	mgmtSvc "github.com/percona/pmm/api/management/v1/json/client/management_service"
+)
+
+func TestListAgentVersions(t *testing.T) {
+	ctx, cancel := context.WithTimeout(pmmapitests.Context, 30*time.Second)
+	t.Cleanup(func() { cancel() })
+
+	t.Run("PMM Agent needs no update", func(t *testing.T) {
+		listAgentVersionsOK, err := client.Default.ManagementService.ListAgentVersions(
+			&mgmtSvc.ListAgentVersionsParams{
+				Context: ctx,
+			})
+		require.NoError(t, err)
+		require.Len(t, listAgentVersionsOK.Payload.AgentVersions, 1)
+
+		expected := pointer.ToString(mgmtSvc.ListAgentVersionsOKBodyAgentVersionsItems0SeverityUPDATESEVERITYUPTODATE)
+		require.Equal(t, expected, listAgentVersionsOK.Payload.AgentVersions[0].Severity)
+	})
+}