test: Add policy test

docs/sandbox.md

@@ -0,0 +1,27 @@
+# Sandbox
+
+Design goal for sandbox in PMG context is to protect against unknown supply chain attacks using principles of least privilege.
+We do not want to re-invent sandbox and likely rely on OS native sandbox primitives. This is at the cost of developer experience,
+where we have to work within the limitations of the sandbox implementations that we use.
+
+## Policy
+
+PMG defines its own policy model. The design goal is simplicity and ease of use. Sandbox implementations are expected to translate
+the policy model into their own native policy format. Rules for policy are:
+
+- Deny by default unless explicitly allowed
+- Deny rules have higher priority than allow rules
+- Policy profile allows binding package managers to a specific sandbox policy
+- Package manager must have a sandbox profile when sandbox is enabled
+- Package manager specific sandbox profile may be disabled to skip sandbox for the package manager
+
+## Enforcement
+
+The sandbox implementation currently only support `block` mode. This means, any policy violation will block the execution of the
+package manager command.
+
+## References
+
+- https://github.com/anthropic-experimental/sandbox-runtime
+- https://geminicli.com/docs/cli/sandbox/
+- https://github.com/containers/bubblewrap

sandbox/registry_test.go

@@ -1,9 +1,11 @@
 package sandbox
 
 import (
+	"os"
 	"testing"
 
 	"github.com/stretchr/testify/assert"
+	"go.yaml.in/yaml/v3"
 )
 
 func TestNewDefaultProfileRegistry(t *testing.T) {
@@ -21,3 +23,70 @@ func TestNewDefaultProfileRegistry(t *testing.T) {
 	assert.NoError(t, err)
 	assert.NotNil(t, pypiRestrictive)
 }
+
+func TestLoadCustomProfile(t *testing.T) {
+	cases := []struct {
+		name   string
+		policy *SandboxPolicy
+		assert func(t *testing.T, policy *SandboxPolicy, err error)
+	}{
+		{
+			name: "valid policy",
+			policy: &SandboxPolicy{
+				Name:            "test",
+				Description:     "test",
+				PackageManagers: []string{"npm"},
+				// At least some rules are required for a policy to be valid
+				Filesystem: FilesystemPolicy{
+					AllowRead:  []string{"/tmp"},
+					AllowWrite: []string{"/tmp"},
+					DenyRead:   []string{"/private/var"},
+					DenyWrite:  []string{"/private/var"},
+				},
+			},
+			assert: func(t *testing.T, policy *SandboxPolicy, err error) {
+				assert.NoError(t, err)
+				assert.NotNil(t, policy)
+				assert.Equal(t, "test", policy.Name)
+				assert.Equal(t, "test", policy.Description)
+				assert.Equal(t, []string{"npm"}, policy.PackageManagers)
+				assert.Equal(t, FilesystemPolicy{
+					AllowRead:  []string{"/tmp"},
+					AllowWrite: []string{"/tmp"},
+					DenyRead:   []string{"/private/var"},
+					DenyWrite:  []string{"/private/var"},
+				}, policy.Filesystem)
+			},
+		},
+		{
+			name: "invalid policy without any rules",
+			policy: &SandboxPolicy{
+				Name:            "test",
+				Description:     "test",
+				PackageManagers: []string{"npm"},
+			},
+			assert: func(t *testing.T, policy *SandboxPolicy, err error) {
+				assert.Error(t, err)
+				assert.Nil(t, policy)
+			},
+		},
+	}
+
+	for _, c := range cases {
+		t.Run(c.name, func(t *testing.T) {
+			registry, err := newDefaultProfileRegistry()
+			assert.NoError(t, err)
+			assert.NotNil(t, registry)
+
+			tempFile, err := os.CreateTemp(t.TempDir(), "sandbox-policy-*.yml")
+			assert.NoError(t, err)
+			defer tempFile.Close()
+
+			err = yaml.NewEncoder(tempFile).Encode(c.policy)
+			assert.NoError(t, err)
+
+			policy, err := registry.LoadCustomProfile(tempFile.Name())
+			c.assert(t, policy, err)
+		})
+	}
+}