virtiofs: Add unit tests

Test the code paths we can use now; parsing and validating a single
mount string.

Not tested:
- Conflicting mounts (cannot be us used yet)
- Setting up mounts (require a running vm)

Author: nirs

pkg/drivers/common/virtiofs/virtiofs_test.go

@@ -0,0 +1,146 @@
+/*
+Copyright 2025 The Kubernetes Authors All rights reserved.
+
+Licensed under the Apache License, Version 2.0 (the "License");
+you may not use this file except in compliance with the License.
+You may obtain a copy of the License at
+
+    http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License.
+*/
+
+package virtiofs_test
+
+import (
+	"fmt"
+	"os"
+	"path/filepath"
+	"testing"
+
+	"github.com/google/uuid"
+
+	"k8s.io/minikube/pkg/drivers/common/virtiofs"
+)
+
+func TestVirtiofsValidateEmptyMountString(t *testing.T) {
+	mounts, err := virtiofs.ValidateMountString("")
+	if err != nil {
+		t.Fatalf("failed to parse empty mount string: %s", err)
+	}
+	if mounts != nil {
+		t.Fatalf("expected nil mounts, got %v", mounts)
+	}
+}
+
+func TestVirtiofsValidateMountString(t *testing.T) {
+	hostPath := t.TempDir()
+	guestPath := "/mnt/models"
+	mountString := fmt.Sprintf("%s:%s", hostPath, guestPath)
+
+	mounts, err := virtiofs.ValidateMountString(mountString)
+	if err != nil {
+		t.Fatalf("failed to parse mountString %q: %s", mountString, err)
+	}
+	if len(mounts) != 1 {
+		t.Fatalf("expected a single mount, got %v", mounts)
+	}
+
+	mount := mounts[0]
+	if mount.HostPath != hostPath {
+		t.Fatalf("expected host path %q, got %q", hostPath, mount.HostPath)
+	}
+	if mount.GuestPath != guestPath {
+		t.Fatalf("expected guest path %q, got %q", guestPath, mount.GuestPath)
+	}
+
+	tag, err := uuid.Parse(mount.Tag)
+	if err != nil {
+		t.Fatalf("failed to parse UUID from mount tag: %s", err)
+	}
+	if tag.Version() != 4 {
+		t.Fatalf("mount tag is not a random UUID")
+	}
+
+	if err := mount.Validate(); err != nil {
+		t.Fatalf("mount is not valid: %s", err)
+	}
+}
+
+func TestVirtiofsParseInvalidMountString(t *testing.T) {
+	for _, tt := range []struct {
+		name        string
+		mountString string
+	}{
+		{
+			name:        "empty",
+			mountString: "",
+		},
+		{
+			name:        "guest path is missing",
+			mountString: "host-path",
+		},
+	} {
+		t.Run(tt.name, func(t *testing.T) {
+			mount, err := virtiofs.ParseMount(tt.mountString)
+			if err == nil {
+				t.Fatalf("invalid mount string %q did not fail to parse", tt.mountString)
+			}
+			if mount != nil {
+				t.Fatalf("expected nil mount for %q, got %v", tt.mountString, mount)
+			}
+		})
+	}
+}
+
+func TestVirtiofsValidateInvalidMount(t *testing.T) {
+	dir := t.TempDir()
+	missing := filepath.Join(dir, "missing")
+	file := filepath.Join(dir, "file")
+
+	f, err := os.Create(file)
+	if err != nil {
+		t.Fatal(err)
+	}
+	f.Close()
+
+	for _, tt := range []struct {
+		name        string
+		mountString string
+	}{
+		{
+			name:        "host path contains virtiofs config separator",
+			mountString: "/host,path:/guest-path",
+		},
+		{
+			name:        "host path is relative",
+			mountString: "host-path:/guest-path",
+		},
+		{
+			name:        "guest path is relative",
+			mountString: fmt.Sprintf("%s:guest-path", dir),
+		},
+		{
+			name:        "host path is missing",
+			mountString: fmt.Sprintf("%s:/guest-path", missing),
+		},
+		{
+			name:        "host path is not a directory",
+			mountString: fmt.Sprintf("%s:/guest-path", file),
+		},
+	} {
+		t.Run(tt.name, func(t *testing.T) {
+			mount, err := virtiofs.ParseMount(tt.mountString)
+			if err != nil {
+				t.Fatalf("failed to parse mount string %q: %s", tt.mountString, err)
+			}
+			if err := mount.Validate(); err == nil {
+				t.Fatalf("invalid mount %q did not failed validation", tt.mountString)
+			}
+		})
+	}
+}