test: Enhance Coverage + CI (#1055)

Reviewed-on: https://gitea.com/gitea/runner/pulls/1055
Reviewed-by: Lunny Xiao <xiaolunwen@gmail.com>
Co-authored-by: bircni <bircni@icloud.com>

act/lookpath/lp_unix_test.go

@@ -0,0 +1,74 @@
+// Copyright 2026 The Gitea Authors. All rights reserved.
+// SPDX-License-Identifier: MIT
+
+//go:build aix || darwin || dragonfly || freebsd || linux || netbsd || openbsd || solaris
+
+package lookpath
+
+import (
+	"errors"
+	"io/fs"
+	"os"
+	"path/filepath"
+	"testing"
+)
+
+type testEnv map[string]string
+
+func (e testEnv) Getenv(name string) string {
+	return e[name]
+}
+
+func TestLookPath2SearchesPathAndEmptyElement(t *testing.T) {
+	dir := t.TempDir()
+	exe := filepath.Join(dir, "tool")
+	if err := os.WriteFile(exe, []byte("#!/bin/sh\n"), 0o755); err != nil {
+		t.Fatal(err)
+	}
+
+	got, err := LookPath2("tool", testEnv{"PATH": string(filepath.ListSeparator) + dir})
+	if err != nil {
+		t.Fatal(err)
+	}
+	if got != exe {
+		t.Fatalf("LookPath2() = %q, want %q", got, exe)
+	}
+}
+
+func TestLookPath2DirectPathDoesNotSearchPath(t *testing.T) {
+	dir := t.TempDir()
+	exe := filepath.Join(dir, "tool")
+	if err := os.WriteFile(exe, []byte("#!/bin/sh\n"), 0o755); err != nil {
+		t.Fatal(err)
+	}
+
+	got, err := LookPath2(exe, testEnv{"PATH": ""})
+	if err != nil {
+		t.Fatal(err)
+	}
+	if got != exe {
+		t.Fatalf("LookPath2() = %q, want %q", got, exe)
+	}
+}
+
+func TestLookPath2ReportsPermissionAndNotFound(t *testing.T) {
+	dir := t.TempDir()
+	file := filepath.Join(dir, "not-executable")
+	if err := os.WriteFile(file, []byte("plain text"), 0o644); err != nil {
+		t.Fatal(err)
+	}
+
+	_, err := LookPath2(file, testEnv{"PATH": dir})
+	var pathErr *Error
+	if !errors.As(err, &pathErr) || !errors.Is(pathErr.Err, fs.ErrPermission) {
+		t.Fatalf("LookPath2(non-executable) error = %v, want fs.ErrPermission wrapped in *Error", err)
+	}
+	if pathErr.Error() != fs.ErrPermission.Error() {
+		t.Fatalf("Error() = %q, want %q", pathErr.Error(), fs.ErrPermission.Error())
+	}
+
+	_, err = LookPath2("missing", testEnv{"PATH": dir})
+	if !errors.As(err, &pathErr) || !errors.Is(pathErr.Err, ErrNotFound) {
+		t.Fatalf("LookPath2(missing) error = %v, want ErrNotFound wrapped in *Error", err)
+	}
+}