Add comprehensive test suite for v2 module with mock provider

Cover all core library logic (Client, Model, Chat, middleware, streaming,
message conversion, request building) using a configurable mock provider
that avoids real API calls. ~50 tests across 7 files.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

v2/model_test.go

@@ -0,0 +1,215 @@
+package llm
+
+import (
+	"context"
+	"errors"
+	"testing"
+
+	"gitea.stevedudenhoeffer.com/steve/go-llm/v2/provider"
+)
+
+func TestModel_Complete(t *testing.T) {
+	mp := newMockProvider(provider.Response{
+		Text: "Hello!",
+		Usage: &provider.Usage{
+			InputTokens:  10,
+			OutputTokens: 5,
+			TotalTokens:  15,
+		},
+	})
+	model := newMockModel(mp)
+
+	resp, err := model.Complete(context.Background(), []Message{UserMessage("Hi")})
+	if err != nil {
+		t.Fatalf("unexpected error: %v", err)
+	}
+	if resp.Text != "Hello!" {
+		t.Errorf("expected text 'Hello!', got %q", resp.Text)
+	}
+	if resp.Usage == nil {
+		t.Fatal("expected usage, got nil")
+	}
+	if resp.Usage.InputTokens != 10 {
+		t.Errorf("expected input tokens 10, got %d", resp.Usage.InputTokens)
+	}
+	if resp.Usage.OutputTokens != 5 {
+		t.Errorf("expected output tokens 5, got %d", resp.Usage.OutputTokens)
+	}
+	if resp.Usage.TotalTokens != 15 {
+		t.Errorf("expected total tokens 15, got %d", resp.Usage.TotalTokens)
+	}
+}
+
+func TestModel_Complete_WithOptions(t *testing.T) {
+	mp := newMockProvider(provider.Response{Text: "ok"})
+	model := newMockModel(mp)
+
+	temp := 0.7
+	maxTok := 100
+	topP := 0.9
+
+	_, err := model.Complete(context.Background(), []Message{UserMessage("test")},
+		WithTemperature(temp),
+		WithMaxTokens(maxTok),
+		WithTopP(topP),
+		WithStop("STOP", "END"),
+	)
+	if err != nil {
+		t.Fatalf("unexpected error: %v", err)
+	}
+
+	req := mp.lastRequest()
+	if req.Temperature == nil || *req.Temperature != temp {
+		t.Errorf("expected temperature %v, got %v", temp, req.Temperature)
+	}
+	if req.MaxTokens == nil || *req.MaxTokens != maxTok {
+		t.Errorf("expected maxTokens %v, got %v", maxTok, req.MaxTokens)
+	}
+	if req.TopP == nil || *req.TopP != topP {
+		t.Errorf("expected topP %v, got %v", topP, req.TopP)
+	}
+	if len(req.Stop) != 2 || req.Stop[0] != "STOP" || req.Stop[1] != "END" {
+		t.Errorf("expected stop [STOP END], got %v", req.Stop)
+	}
+}
+
+func TestModel_Complete_Error(t *testing.T) {
+	wantErr := errors.New("provider error")
+	mp := newMockProviderFunc(func(ctx context.Context, req provider.Request) (provider.Response, error) {
+		return provider.Response{}, wantErr
+	})
+	model := newMockModel(mp)
+
+	_, err := model.Complete(context.Background(), []Message{UserMessage("Hi")})
+	if err == nil {
+		t.Fatal("expected error, got nil")
+	}
+	if !errors.Is(err, wantErr) {
+		t.Errorf("expected error %v, got %v", wantErr, err)
+	}
+}
+
+func TestModel_Complete_WithTools(t *testing.T) {
+	mp := newMockProvider(provider.Response{Text: "done"})
+	model := newMockModel(mp)
+
+	tool := DefineSimple("greet", "Says hello", func(ctx context.Context) (string, error) {
+		return "hello", nil
+	})
+	tb := NewToolBox(tool)
+
+	_, err := model.Complete(context.Background(), []Message{UserMessage("test")}, WithTools(tb))
+	if err != nil {
+		t.Fatalf("unexpected error: %v", err)
+	}
+
+	req := mp.lastRequest()
+	if len(req.Tools) != 1 {
+		t.Fatalf("expected 1 tool, got %d", len(req.Tools))
+	}
+	if req.Tools[0].Name != "greet" {
+		t.Errorf("expected tool name 'greet', got %q", req.Tools[0].Name)
+	}
+	if req.Tools[0].Description != "Says hello" {
+		t.Errorf("expected tool description 'Says hello', got %q", req.Tools[0].Description)
+	}
+}
+
+func TestClient_Model(t *testing.T) {
+	mp := newMockProvider(provider.Response{Text: "hi"})
+	client := newClient(mp)
+	model := client.Model("test-model")
+
+	resp, err := model.Complete(context.Background(), []Message{UserMessage("test")})
+	if err != nil {
+		t.Fatalf("unexpected error: %v", err)
+	}
+	if resp.Text != "hi" {
+		t.Errorf("expected 'hi', got %q", resp.Text)
+	}
+
+	req := mp.lastRequest()
+	if req.Model != "test-model" {
+		t.Errorf("expected model 'test-model', got %q", req.Model)
+	}
+}
+
+func TestClient_WithMiddleware(t *testing.T) {
+	var called bool
+	mw := func(next CompletionFunc) CompletionFunc {
+		return func(ctx context.Context, model string, messages []Message, cfg *requestConfig) (Response, error) {
+			called = true
+			return next(ctx, model, messages, cfg)
+		}
+	}
+
+	mp := newMockProvider(provider.Response{Text: "ok"})
+	client := newClient(mp).WithMiddleware(mw)
+	model := client.Model("test-model")
+
+	_, err := model.Complete(context.Background(), []Message{UserMessage("test")})
+	if err != nil {
+		t.Fatalf("unexpected error: %v", err)
+	}
+	if !called {
+		t.Error("middleware was not called")
+	}
+}
+
+func TestModel_WithMiddleware(t *testing.T) {
+	var order []string
+	mw1 := func(next CompletionFunc) CompletionFunc {
+		return func(ctx context.Context, model string, messages []Message, cfg *requestConfig) (Response, error) {
+			order = append(order, "mw1")
+			return next(ctx, model, messages, cfg)
+		}
+	}
+	mw2 := func(next CompletionFunc) CompletionFunc {
+		return func(ctx context.Context, model string, messages []Message, cfg *requestConfig) (Response, error) {
+			order = append(order, "mw2")
+			return next(ctx, model, messages, cfg)
+		}
+	}
+
+	mp := newMockProvider(provider.Response{Text: "ok"})
+	model := newMockModel(mp).WithMiddleware(mw1).WithMiddleware(mw2)
+
+	_, err := model.Complete(context.Background(), []Message{UserMessage("test")})
+	if err != nil {
+		t.Fatalf("unexpected error: %v", err)
+	}
+	if len(order) != 2 || order[0] != "mw1" || order[1] != "mw2" {
+		t.Errorf("expected middleware order [mw1 mw2], got %v", order)
+	}
+}
+
+func TestModel_Complete_NoUsage(t *testing.T) {
+	mp := newMockProvider(provider.Response{Text: "no usage"})
+	model := newMockModel(mp)
+
+	resp, err := model.Complete(context.Background(), []Message{UserMessage("test")})
+	if err != nil {
+		t.Fatalf("unexpected error: %v", err)
+	}
+	if resp.Usage != nil {
+		t.Errorf("expected nil usage, got %+v", resp.Usage)
+	}
+}
+
+func TestModel_Complete_ResponseMessage(t *testing.T) {
+	mp := newMockProvider(provider.Response{Text: "response text"})
+	model := newMockModel(mp)
+
+	resp, err := model.Complete(context.Background(), []Message{UserMessage("test")})
+	if err != nil {
+		t.Fatalf("unexpected error: %v", err)
+	}
+
+	msg := resp.Message()
+	if msg.Role != RoleAssistant {
+		t.Errorf("expected role assistant, got %v", msg.Role)
+	}
+	if msg.Content.Text != "response text" {
+		t.Errorf("expected text 'response text', got %q", msg.Content.Text)
+	}
+}