test(agentcompat): harden deterministic fixtures

Co-authored-by: naiba/CloudCode <hi+cloudcode@nai.ba>

integration/agentcompat/internal/testpaths/source.go

@@ -0,0 +1,62 @@
+package testpaths
+
+import (
+	"errors"
+	"os"
+	"path/filepath"
+)
+
+func NezhaSource(start string) (string, error) {
+	if configured := os.Getenv("NEZHA_SOURCE"); configured != "" {
+		return absoluteDirectory(configured)
+	}
+	return findModuleRoot(start)
+}
+
+func AgentSource(nezhaSource string) (string, error) {
+	if configured := os.Getenv("AGENT_SOURCE"); configured != "" {
+		return absoluteDirectory(configured)
+	}
+	root, err := absoluteDirectory(nezhaSource)
+	if err != nil {
+		return "", err
+	}
+	return absoluteDirectory(filepath.Join(filepath.Dir(root), "agent"))
+}
+
+func absoluteDirectory(raw string) (string, error) {
+	if raw == "" || !filepath.IsAbs(raw) {
+		return "", errors.New("source path must be absolute")
+	}
+	clean := filepath.Clean(raw)
+	info, err := os.Stat(clean)
+	if err != nil {
+		return "", err
+	}
+	if !info.IsDir() {
+		return "", errors.New("source path must be a directory")
+	}
+	return clean, nil
+}
+
+func findModuleRoot(start string) (string, error) {
+	if start == "" {
+		start, _ = os.Getwd()
+	}
+	absolute, err := filepath.Abs(start)
+	if err != nil {
+		return "", err
+	}
+	if info, statErr := os.Stat(absolute); statErr == nil && !info.IsDir() {
+		absolute = filepath.Dir(absolute)
+	}
+	for directory := absolute; ; directory = filepath.Dir(directory) {
+		if _, err := os.Stat(filepath.Join(directory, "go.mod")); err == nil {
+			return directory, nil
+		}
+		parent := filepath.Dir(directory)
+		if parent == directory {
+			return "", errors.New("module root not found")
+		}
+	}
+}