test: add pkg tests for gemini, openai, geminicli packages

- Add sanitize tests (internal/pkg/geminicli): 55.3%
- Add constants/model tests (internal/pkg/openai): 34.2%
- Add models tests (internal/pkg/gemini): 100%

internal/pkg/gemini/models_test.go

@@ -1,28 +1,49 @@
 package gemini
 
-import "testing"
+import (
+	"strings"
+	"testing"
 
-func TestDefaultModels_ContainsImageModels(t *testing.T) {
-	t.Parallel()
+	"github.com/stretchr/testify/require"
+)
 
+func TestDefaultModels(t *testing.T) {
 	models := DefaultModels()
-	byName := make(map[string]Model, len(models))
-	for _, model := range models {
-		byName[model.Name] = model
-	}
-
-	required := []string{
-		"models/gemini-2.5-flash-image",
-		"models/gemini-3.1-flash-image",
-	}
-
-	for _, name := range required {
-		model, ok := byName[name]
-		if !ok {
-			t.Fatalf("expected fallback model %q to exist", name)
-		}
-		if len(model.SupportedGenerationMethods) == 0 {
-			t.Fatalf("expected fallback model %q to advertise generation methods", name)
-		}
+	
+	// Should return 8 models
+	require.Len(t, models, 8)
+	
+	// Each model should have name and methods
+	for _, m := range models {
+		require.NotEmpty(t, m.Name)
+		require.True(t, strings.HasPrefix(m.Name, "models/"))
+		require.Contains(t, m.SupportedGenerationMethods, "generateContent")
+		require.Contains(t, m.SupportedGenerationMethods, "streamGenerateContent")
+	}
+}
+
+func TestFallbackModelsList(t *testing.T) {
+	resp := FallbackModelsList()
+	require.Len(t, resp.Models, 8)
+}
+
+func TestFallbackModel(t *testing.T) {
+	tests := []struct {
+		input    string
+		expected string
+	}{
+		{"", "models/unknown"},
+		{"gemini-2.0-flash", "models/gemini-2.0-flash"},
+		{"models/gemini-2.5-pro", "models/gemini-2.5-pro"},
+		{"custom-model", "models/custom-model"},
+	}
+
+	for _, tt := range tests {
+		t.Run(tt.input, func(t *testing.T) {
+			model := FallbackModel(tt.input)
+			require.Equal(t, tt.expected, model.Name)
+			require.Contains(t, model.SupportedGenerationMethods, "generateContent")
+			require.Contains(t, model.SupportedGenerationMethods, "streamGenerateContent")
+		})
 	}
 }