fix(lint): normalise empty orchestration outputs

Co-Authored-By: Virgil <virgil@lethean.io>

pkg/lint/detect_project.go

@@ -35,7 +35,7 @@ func Detect(path string) []string {
 	seen := make(map[string]bool)
 	info, err := os.Stat(path)
 	if err != nil {
-		return nil
+		return []string{}
 	}
 
 	if !info.IsDir() {
@@ -113,5 +113,8 @@ func sortedDetectedLanguages(seen map[string]bool) []string {
 		languages = append(languages, language)
 	}
 	slices.Sort(languages)
+	if languages == nil {
+		return []string{}
+	}
 	return languages
 }

pkg/lint/detect_project_test.go

@@ -42,3 +42,7 @@ func TestDetectFromFiles_Good(t *testing.T) {
 		detectFromFiles(files),
 	)
 }
+
+func TestDetect_MissingPathReturnsEmptySlice(t *testing.T) {
+	assert.Equal(t, []string{}, Detect(filepath.Join(t.TempDir(), "missing")))
+}

pkg/lint/service.go

@@ -144,6 +144,15 @@ func (s *Service) Run(ctx context.Context, input RunInput) (Report, error) {
 	findings = dedupeFindings(findings)
 	sortToolRuns(toolRuns)
 	sortFindings(findings)
+	if languages == nil {
+		languages = []string{}
+	}
+	if toolRuns == nil {
+		toolRuns = []ToolRun{}
+	}
+	if findings == nil {
+		findings = []Finding{}
+	}
 
 	report := Report{
 		Project:   projectName(input.Path),
@@ -179,6 +188,9 @@ func (s *Service) Tools(languages []string) []ToolInfo {
 	slices.SortFunc(tools, func(left ToolInfo, right ToolInfo) int {
 		return strings.Compare(left.Name, right.Name)
 	})
+	if tools == nil {
+		return []ToolInfo{}
+	}
 	return tools
 }
 

pkg/lint/service_test.go

@@ -373,6 +373,12 @@ func TestServiceRun_Good_DeduplicatesMergedFindings(t *testing.T) {
 	assert.Equal(t, 1, report.Summary.Total)
 }
 
+func TestServiceTools_EmptyInventoryReturnsEmptySlice(t *testing.T) {
+	tools := (&Service{}).Tools(nil)
+	require.NotNil(t, tools)
+	assert.Empty(t, tools)
+}
+
 type duplicateAdapter struct {
 	name    string
 	finding Finding