test: Support virtiofs mounts

Use findmnt command to get the mounted filesystem details cleanly.

We use the actual mount fstype instead of driver name check so we can
switch drivers to virtiofs without changing the test.

For virtiofs mount we skip options validation since we don't support
setting virtiofs options yet, and the options are not the same as 9p
options.

For 9p mounts the uid= and gid= flags were fixed to match the real flags
(dfltuid=,dfltgid=). The issue was hidden by imprecise string matching.

Author: nirs

test/integration/mount_start_test.go

@@ -22,10 +22,13 @@ import (
 	"context"
 	"fmt"
 	"os/exec"
+	"slices"
 	"strconv"
 	"strings"
 	"testing"
 	"time"
+
+	"k8s.io/minikube/test/integration/findmnt"
 )
 
 const (
@@ -139,26 +142,47 @@ func validateMount(ctx context.Context, t *testing.T, profile string) {
 	}
 
 	args = sshArgs
-	args = append(args, "mount", "|", "grep", "9p")
+	args = append(args, "findmnt", "--json", guestPath)
 	rr, err = Run(t, exec.CommandContext(ctx, Target(), args...))
 	if err != nil {
 		t.Fatalf("failed to get mount information: %v", err)
 	}
 
+	result, err := findmnt.ParseOutput(rr.Stdout.Bytes())
+	if err != nil {
+		t.Fatalf("failed to parse command output %q: %s", rr.Command(), rr.Output())
+	}
+
+	if len(result.Filesystems) == 0 {
+		t.Fatalf("no filesystems found")
+	}
+
+	fs := result.Filesystems[0]
+	if fs.FSType == "virtiofs" {
+		t.Logf("virtiofs options not supported yet")
+		return
+	}
+
+	if fs.FSType != "9p" {
+		t.Fatalf("unexpected filesystem: %q", fs.FSType)
+	}
+
+	options := strings.Split(fs.Options, ",")
+
 	flags := []struct {
 		key      string
 		expected string
 	}{
-		{"gid", mountGID},
+		{"dfltgid", mountGID},
+		{"dfltuid", mountUID},
 		{"msize", mountMSize},
 		{"port", mountPort()},
-		{"uid", mountUID},
 	}
 
 	for _, flag := range flags {
 		want := fmt.Sprintf("%s=%s", flag.key, flag.expected)
-		if !strings.Contains(rr.Output(), want) {
-			t.Errorf("wanted %s to be: %q; got: %q", flag.key, want, rr.Output())
+		if !slices.Contains(options, want) {
+			t.Errorf("wanted %s to be: %q; got: %q", flag.key, want, options)
 		}
 	}
 }