acceptance: Change rpk registry schema list to fail eventually

In the execution sometimes the schema registry subsystem is not ready to handle
requests. To make test suite more stable single assertion was replaced with
Eventually function.

To add more the stdout was not reset after each rpk command. Now it will be
truncated.

Author: RafalKorepta

acceptance/steps/rpk.go

@@ -4,6 +4,7 @@ import (
 	"bytes"
 	"context"
 	"strings"
+	"time"
 
 	"github.com/cucumber/godog"
 	"github.com/stretchr/testify/require"
@@ -105,15 +106,31 @@ func checkRPKCommands(ctx context.Context, t framework.TestingT, clusterName str
 			Stderr:    &stderr,
 		}), "\nStdout: %s\nStderr: %s\n", stdout.String(), stderr.String())
 		require.Len(t, stderr.Bytes(), 0)
-
-		require.NoErrorf(t, ctl.Exec(ctx, &p, kube.ExecOptions{
-			Container: "redpanda",
-			Command:   []string{"rpk", "registry", "schema", "list"},
-			Stdin:     nil,
-			Stdout:    &stdout,
-			Stderr:    &stderr,
-		}), "\nStdout: %s\nStderr: %s\n", stdout.String(), stderr.String())
-		require.Len(t, stderr.Bytes(), 0)
+		stdout.Reset()
+
+		require.Eventually(t, func() bool {
+			command := []string{"rpk", "registry", "schema", "list"}
+			err := ctl.Exec(ctx, &p, kube.ExecOptions{
+				Container: "redpanda",
+				Command:   command,
+				Stdin:     nil,
+				Stdout:    &stdout,
+				Stderr:    &stderr,
+			})
+			if err != nil {
+				t.Logf("rpk command %q failed with error: %v\nStdout: %s\nStderr: %s\n", strings.Join(command, " "), err, stdout.String(), stderr.String())
+				stdout.Reset()
+				return false
+			}
+			if len(stderr.Bytes()) != 0 {
+				t.Logf("rpk command %q failed with \nStdout: %s\nStderr: %s\n", strings.Join(command, " "), stdout.String(), stderr.String())
+				stderr.Reset()
+				stdout.Reset()
+				return false
+			}
+			return true
+		}, time.Minute, 10*time.Second)
+		stdout.Reset()
 
 		require.NoErrorf(t, ctl.Exec(ctx, &p, kube.ExecOptions{
 			Container: "redpanda",
@@ -123,5 +140,6 @@ func checkRPKCommands(ctx context.Context, t framework.TestingT, clusterName str
 			Stderr:    &stderr,
 		}), "\nStdout: %s\nStderr: %s\n", stdout.String(), stderr.String())
 		require.Len(t, stderr.Bytes(), 0)
+
 	}
 }