Centralize effective config loading and path resolution

internal/core/config/effective_config_test.go

@@ -0,0 +1,163 @@
+package config
+
+import (
+	"os"
+	"path/filepath"
+	"strings"
+	"testing"
+)
+
+func TestResolveConfigPathWithLookupMatrix(t *testing.T) {
+	statFor := func(existing map[string]bool) func(string) (os.FileInfo, error) {
+		return func(path string) (os.FileInfo, error) {
+			if existing[path] {
+				return nil, nil
+			}
+			return nil, os.ErrNotExist
+		}
+	}
+
+	tests := []struct {
+		name               string
+		cliPath            string
+		cliPathSet         bool
+		lookup             func(string) (string, bool)
+		stat               func(string) (os.FileInfo, error)
+		defaultSearchPaths []string
+		wantPath           string
+		wantSource         string
+		wantErrContains    string
+	}{
+		{
+			name:       "explicit config path",
+			cliPath:    "/tmp/explicit.yml",
+			cliPathSet: true,
+			lookup:     func(string) (string, bool) { return "", false },
+			stat:       statFor(map[string]bool{"/tmp/explicit.yml": true}),
+			defaultSearchPaths: []string{
+				"/usr/local/etc/audita/config.yml",
+				"/etc/audita/config.yml",
+			},
+			wantPath:   "/tmp/explicit.yml",
+			wantSource: "flag",
+		},
+		{
+			name:       "env config path",
+			cliPathSet: false,
+			lookup: func(key string) (string, bool) {
+				if key == "AUDITA_CONFIG" {
+					return "/tmp/from-env.yml", true
+				}
+				return "", false
+			},
+			stat:               statFor(map[string]bool{"/tmp/from-env.yml": true}),
+			defaultSearchPaths: []string{"/usr/local/etc/audita/config.yml", "/etc/audita/config.yml"},
+			wantPath:           "/tmp/from-env.yml",
+			wantSource:         "env",
+		},
+		{
+			name:       "default search path",
+			cliPathSet: false,
+			lookup:     func(string) (string, bool) { return "", false },
+			stat: statFor(map[string]bool{
+				"/usr/local/etc/audita/config.yml": true,
+				"/etc/audita/config.yml":           true,
+			}),
+			defaultSearchPaths: []string{"/usr/local/etc/audita/config.yml", "/etc/audita/config.yml"},
+			wantPath:           "/usr/local/etc/audita/config.yml",
+			wantSource:         "default",
+		},
+		{
+			name:       "explicit missing path",
+			cliPath:    "/tmp/missing.yml",
+			cliPathSet: true,
+			lookup:     func(string) (string, bool) { return "", false },
+			stat:       statFor(map[string]bool{}),
+			defaultSearchPaths: []string{
+				"/usr/local/etc/audita/config.yml",
+				"/etc/audita/config.yml",
+			},
+			wantErrContains: "config file not found",
+		},
+		{
+			name:       "missing env path",
+			cliPathSet: false,
+			lookup: func(key string) (string, bool) {
+				if key == "AUDITA_CONFIG" {
+					return "/tmp/missing-from-env.yml", true
+				}
+				return "", false
+			},
+			stat:               statFor(map[string]bool{}),
+			defaultSearchPaths: []string{"/usr/local/etc/audita/config.yml", "/etc/audita/config.yml"},
+			wantErrContains:    "config file not found",
+		},
+		{
+			name:       "missing default paths",
+			cliPathSet: false,
+			lookup:     func(string) (string, bool) { return "", false },
+			stat:       statFor(map[string]bool{}),
+			defaultSearchPaths: []string{
+				"/usr/local/etc/audita/config.yml",
+				"/etc/audita/config.yml",
+			},
+			wantPath:   "",
+			wantSource: "",
+		},
+	}
+
+	for _, tc := range tests {
+		t.Run(tc.name, func(t *testing.T) {
+			gotPath, gotSource, err := resolveConfigPathWithLookup(tc.cliPath, tc.cliPathSet, tc.lookup, tc.stat, tc.defaultSearchPaths)
+			if tc.wantErrContains != "" {
+				if err == nil || !strings.Contains(err.Error(), tc.wantErrContains) {
+					t.Fatalf("expected error containing %q, got %v", tc.wantErrContains, err)
+				}
+				return
+			}
+			if err != nil {
+				t.Fatalf("unexpected error: %v", err)
+			}
+			if gotPath != tc.wantPath || gotSource != tc.wantSource {
+				t.Fatalf("unexpected result: got path=%q source=%q, want path=%q source=%q", gotPath, gotSource, tc.wantPath, tc.wantSource)
+			}
+		})
+	}
+}
+
+func TestLoadEffectiveConfigWithLookupAppliesDefaultsFileThenEnv(t *testing.T) {
+	tempDir := t.TempDir()
+	configPath := filepath.Join(tempDir, "config.yml")
+	configYAML := "version: 1\nllm:\n  proposal:\n    model: file-model\n"
+	if err := os.WriteFile(configPath, []byte(configYAML), 0o644); err != nil {
+		t.Fatalf("write config file: %v", err)
+	}
+
+	lookup := func(key string) (string, bool) {
+		switch key {
+		case "AUDITA_CONFIG":
+			return configPath, true
+		case "AUDITA_MODEL":
+			return "env-model", true
+		default:
+			return "", false
+		}
+	}
+
+	result, err := loadEffectiveConfigWithLookup("", false, lookup, os.Stat, DefaultConfigSearchPaths)
+	if err != nil {
+		t.Fatalf("loadEffectiveConfigWithLookup error: %v", err)
+	}
+	if result.ConfigPath != configPath {
+		t.Fatalf("unexpected config path: %q", result.ConfigPath)
+	}
+	if result.ConfigSource != "env" {
+		t.Fatalf("unexpected config source: %q", result.ConfigSource)
+	}
+	if result.ConfigVersion == nil || *result.ConfigVersion != SupportedFileConfigVersion {
+		t.Fatalf("unexpected config version: %#v", result.ConfigVersion)
+	}
+	if result.Config.PrimaryLLM.Model != "env-model" {
+		t.Fatalf("expected env override to win over file value, got %q", result.Config.PrimaryLLM.Model)
+	}
+}