Isolate tests from global git config to prevent gpg-agent/pinentry (#531)

## Summary

- Add `GIT_CONFIG_GLOBAL=/dev/null`, `GIT_CONFIG_NOSYSTEM=1`, and
`GIT_TERMINAL_PROMPT=0` to `testenv.RunIsolatedMain()` so tests never
read global/system git config or prompt for input — prevents
`commit.gpgsign=true` from triggering gpg-agent/pinentry during test
commits
- Add `TestMain` calling `RunIsolatedMain()` to `internal/git`,
`internal/prompt`, and `internal/worktree` packages that create git
commits in tests but were missing it
- Fix `TestEnsureAbsoluteHooksPath` subtest that simulates global config
by explicitly setting `GIT_CONFIG_GLOBAL` to its fake gitconfig file
(since `/dev/null` override would otherwise shadow it)

🤖 Generated with [Claude Code](https://claude.com/claude-code)

---------

Co-authored-by: Claude Opus 4.6 <noreply@anthropic.com>

Author: cpcloud

internal/git/git_test.go

@@ -8,10 +8,15 @@ import (
 	"strings"
 	"testing"
 
+	"github.com/roborev-dev/roborev/internal/testenv"
 	"github.com/stretchr/testify/assert"
 	"github.com/stretchr/testify/require"
 )
 
+func TestMain(m *testing.M) {
+	os.Exit(testenv.RunIsolatedMain(m))
+}
+
 type TestRepo struct {
 	T   *testing.T
 	Dir string
@@ -370,6 +375,7 @@ func TestEnsureAbsoluteHooksPath(t *testing.T) {
 				fakeHome, ".config",
 			))
 			globalCfg := filepath.Join(fakeHome, ".gitconfig")
+			t.Setenv("GIT_CONFIG_GLOBAL", globalCfg)
 			err := os.WriteFile(globalCfg, []byte(
 				"[core]\n\thooksPath = .githooks\n",
 			), 0644)

internal/prompt/prompt_test.go

@@ -9,11 +9,16 @@ import (
 	"github.com/roborev-dev/roborev/internal/config"
 	gitpkg "github.com/roborev-dev/roborev/internal/git"
 	"github.com/roborev-dev/roborev/internal/storage"
+	"github.com/roborev-dev/roborev/internal/testenv"
 	"github.com/roborev-dev/roborev/internal/testutil"
 	"github.com/stretchr/testify/assert"
 	"github.com/stretchr/testify/require"
 )
 
+func TestMain(m *testing.M) {
+	os.Exit(testenv.RunIsolatedMain(m))
+}
+
 func TestBuildPromptWithoutContext(t *testing.T) {
 	repoPath, commits := setupTestRepo(t)
 	targetSHA := commits[len(commits)-1]

internal/testenv/testenv.go

@@ -23,6 +23,16 @@ func RunIsolatedMain(m *testing.M) int {
 	}
 	defer os.RemoveAll(tmpDir)
 
+	// Prevent global/system git config from leaking into tests.
+	// Without this, commit.gpgsign=true in global config triggers
+	// gpg-agent/pinentry during test commits. os.DevNull is
+	// cross-platform (/dev/null on Unix, NUL on Windows).
+	os.Setenv("GIT_CONFIG_GLOBAL", os.DevNull)
+	os.Setenv("GIT_CONFIG_NOSYSTEM", "1")
+	// Never allow git to prompt for input (passwords, passphrases, etc).
+	// If something unexpected tries to prompt, fail fast instead of blocking.
+	os.Setenv("GIT_TERMINAL_PROMPT", "0")
+
 	origEnv, hasEnv := os.LookupEnv("ROBOREV_DATA_DIR")
 	os.Setenv("ROBOREV_DATA_DIR", tmpDir)
 	defer func() {

internal/worktree/worktree_test.go

@@ -2,15 +2,21 @@ package worktree
 
 import (
 	"fmt"
-	"github.com/stretchr/testify/assert"
-	"github.com/stretchr/testify/require"
 	"os"
 	"os/exec"
 	"path/filepath"
 	"strings"
 	"testing"
+
+	"github.com/roborev-dev/roborev/internal/testenv"
+	"github.com/stretchr/testify/assert"
+	"github.com/stretchr/testify/require"
 )
 
+func TestMain(m *testing.M) {
+	os.Exit(testenv.RunIsolatedMain(m))
+}
+
 func runGit(t *testing.T, dir string, args ...string) string {
 	t.Helper()
 	cmd := exec.Command("git", append([]string{"-C", dir}, args...)...)