pam-moduler: Add test that generates a new debug module and verify it works

We mimic what pam_debug.so does by default, by implementing a similar
module fully in go, generated using pam-moduler.

This requires various utilities to generate the module and run the tests
that are in a separate internal modules so that it can be shared between
multiple implementations

cmd/pam-moduler/tests/internal/utils/test-setup_test.go

@@ -0,0 +1,180 @@
+package utils
+
+import (
+	"fmt"
+	"math/rand"
+	"os"
+	"path/filepath"
+	"strings"
+	"testing"
+)
+
+func isDir(t *testing.T, path string) bool {
+	t.Helper()
+	if file, err := os.Open(path); err == nil {
+		if fileInfo, err := file.Stat(); err == nil {
+			return fileInfo.IsDir()
+		}
+		t.Fatalf("error: %v", err)
+	} else {
+		t.Fatalf("error: %v", err)
+	}
+	return false
+}
+
+func Test_CreateTemporaryDir(t *testing.T) {
+	t.Parallel()
+	ts := NewTestSetup(t)
+	dir := ts.CreateTemporaryDir("")
+	if !isDir(t, dir) {
+		t.Fatalf("%s not a directory", dir)
+	}
+
+	dir = ts.CreateTemporaryDir("foo-prefix-*")
+	if !isDir(t, dir) {
+		t.Fatalf("%s not a directory", dir)
+	}
+}
+
+func Test_TestSetupWithWorkDir(t *testing.T) {
+	t.Parallel()
+	ts := NewTestSetup(t, WithWorkDir())
+	if !isDir(t, ts.WorkDir()) {
+		t.Fatalf("%s not a directory", ts.WorkDir())
+	}
+}
+
+func Test_CreateService(t *testing.T) {
+	t.Parallel()
+	ts := NewTestSetup(t)
+
+	tests := map[string]struct {
+		services        []ServiceLine
+		expectedContent string
+	}{
+		"empty":         {},
+		"CApital-Empty": {},
+		"auth-sufficient-permit": {
+			services: []ServiceLine{
+				{Auth, Sufficient, Permit.String(), []string{}},
+			},
+			expectedContent: "auth	sufficient	pam_permit.so",
+		},
+		"auth-sufficient-permit-args": {
+			services: []ServiceLine{
+				{Auth, Required, Deny.String(), []string{"a b c [d e]"}},
+			},
+			expectedContent: "auth	required	pam_deny.so	a b c [d e]",
+		},
+		"complete-custom": {
+			services: []ServiceLine{
+				{Account, Required, "pam_account_module.so", []string{"a", "b", "c", "[d e]"}},
+				{Account, Required, Deny.String(), []string{}},
+				{Auth, Requisite, "pam_auth_module.so", []string{}},
+				{Auth, Requisite, Deny.String(), []string{}},
+				{Password, Sufficient, "pam_password_module.so", []string{"arg"}},
+				{Password, Sufficient, Deny.String(), []string{}},
+				{Session, Optional, "pam_session_module.so", []string{""}},
+				{Session, Optional, Deny.String(), []string{}},
+			},
+			expectedContent: `account	required	pam_account_module.so	a b c [d e]
+account	required	pam_deny.so
+auth	requisite	pam_auth_module.so
+auth	requisite	pam_deny.so
+password	sufficient	pam_password_module.so	arg
+password	sufficient	pam_deny.so
+session	optional	pam_session_module.so
+session	optional	pam_deny.so`,
+		},
+	}
+
+	for name, tc := range tests {
+		tc := tc
+		name := name
+		t.Run(name, func(t *testing.T) {
+			t.Parallel()
+			service := ts.CreateService(name, tc.services)
+
+			if filepath.Base(service) != strings.ToLower(name) {
+				t.Fatalf("Invalid service name %s", service)
+			}
+
+			if bytes, err := os.ReadFile(service); err != nil {
+				t.Fatalf("Failed reading %s: %v", service, err)
+			} else {
+				if string(bytes) != tc.expectedContent {
+					t.Fatalf("Unexpected file content:\n%s\n---\n%s",
+						tc.expectedContent, string(bytes))
+				}
+			}
+		})
+	}
+}
+
+func Test_GenerateModule(t *testing.T) {
+	ts := NewTestSetup(t)
+	dir := ts.CreateTemporaryDir("")
+	if !isDir(t, dir) {
+		t.Fatalf("%s not a directory", dir)
+	}
+
+	f, err := os.Create(filepath.Join(dir, "test-generate.go"))
+	if err != nil {
+		t.Fatalf("can't create file %v", err)
+	}
+	defer f.Close()
+
+	randomName := ""
+	for i := 0; i < 10; i++ {
+		// #nosec:G404 - it's a test, we don't care.
+		randomName += string(byte('a' + rand.Intn('z'-'a')))
+	}
+
+	wantFile := randomName + ".so"
+	fmt.Fprintf(f, `//go:generate touch %s
+package generate_file
+`, wantFile)
+
+	mod, err := os.Create(filepath.Join(dir, "go.mod"))
+	if err != nil {
+		t.Fatalf("can't create file %v", err)
+	}
+	defer mod.Close()
+
+	fmt.Fprintf(mod, `module example.com/greetings
+
+go 1.20
+`)
+
+	fakeModule := ts.GenerateModule(dir, wantFile)
+	if _, err := os.Stat(fakeModule); err != nil {
+		t.Fatalf("module not generated %v", err)
+	}
+
+	fmt.Fprint(f, `//go:generate touch pam_go.so
+package generate_file
+`, wantFile)
+
+	fakeModule = ts.GenerateModuleDefault(dir)
+	if _, err := os.Stat(fakeModule); err != nil {
+		t.Fatalf("module not generated %v", err)
+	}
+}
+
+func Test_GetCurrentFileDir(t *testing.T) {
+	t.Parallel()
+
+	ts := NewTestSetup(t)
+	if !strings.HasSuffix(ts.GetCurrentFileDir(), filepath.Join("internal", "utils")) {
+		t.Fatalf("unexpected file %v", ts.GetCurrentFileDir())
+	}
+}
+
+func Test_GetCurrentFile(t *testing.T) {
+	t.Parallel()
+
+	ts := NewTestSetup(t)
+	if !strings.HasSuffix(ts.GetCurrentFile(), filepath.Join("utils", "test-setup_test.go")) {
+		t.Fatalf("unexpected file %v", ts.GetCurrentFile())
+	}
+}