zf: add Gemini TTS provider

1 files changed, 143 insertions, 0 deletions

diff --git a/internal/audio/gemini_provider_test.go b/internal/audio/gemini_provider_test.go
new file mode 100644
index 0000000..1c04f55
--- /dev/null
+++ b/internal/audio/gemini_provider_test.go
@@ -0,0 +1,143 @@
+package audio
+
+import (
+	"os"
+	"path/filepath"
+	"strings"
+	"testing"
+
+	"google.golang.org/genai"
+)
+
+func TestNewGeminiProvider(t *testing.T) {
+	tests := []struct {
+		name    string
+		config  *Config
+		wantErr bool
+	}{
+		{
+			name:    "missing google api key",
+			config:  &Config{},
+			wantErr: true,
+		},
+		{
+			name: "valid config",
+			config: &Config{
+				GoogleAPIKey:   "test-key",
+				GeminiTTSModel: "gemini-2.5-flash",
+				GeminiVoice:    "Kore",
+				GeminiSpeed:    1.0,
+			},
+			wantErr: false,
+		},
+	}
+
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			provider, err := NewGeminiProvider(tt.config)
+			if (err != nil) != tt.wantErr {
+				t.Fatalf("NewGeminiProvider() error = %v, wantErr %v", err, tt.wantErr)
+			}
+			if err != nil {
+				return
+			}
+
+			if provider.Name() != "gemini" {
+				t.Fatalf("Name() = %q, want %q", provider.Name(), "gemini")
+			}
+		})
+	}
+}
+
+func TestGeminiProviderIsAvailable(t *testing.T) {
+	provider := &GeminiProvider{
+		config: &Config{GoogleAPIKey: "test-key"},
+	}
+
+	if err := provider.IsAvailable(); err != nil {
+		t.Fatalf("IsAvailable() unexpected error: %v", err)
+	}
+
+	provider.config.GoogleAPIKey = ""
+	if err := provider.IsAvailable(); err == nil {
+		t.Fatal("IsAvailable() expected error when API key is missing")
+	}
+}
+
+func TestGeminiProviderBuildPrompt(t *testing.T) {
+	provider := &GeminiProvider{
+		config: &Config{
+			GeminiVoice: "Kore",
+			GeminiSpeed: 0.92,
+		},
+	}
+
+	prompt := provider.buildPrompt("ябълка")
+
+	for _, want := range []string{
+		"Bulgarian language",
+		"authentic Bulgarian phonetics",
+		"Speak slowly and clearly for language learners.",
+		"ябълка",
+		"voice named Kore",
+	} {
+		if !strings.Contains(prompt, want) {
+			t.Fatalf("buildPrompt() = %q, missing %q", prompt, want)
+		}
+	}
+}
+
+func TestExtractAudioData(t *testing.T) {
+	response := &genai.GenerateContentResponse{
+		Candidates: []*genai.Candidate{
+			{
+				Content: &genai.Content{
+					Parts: []*genai.Part{
+						{
+							InlineData: &genai.Blob{
+								Data:     []byte{0x01, 0x02, 0x03},
+								MIMEType: "audio/pcm",
+							},
+						},
+					},
+				},
+			},
+		},
+	}
+
+	data, mimeType, err := extractAudioData(response)
+	if err != nil {
+		t.Fatalf("extractAudioData() unexpected error: %v", err)
+	}
+
+	if mimeType != "audio/pcm" {
+		t.Fatalf("extractAudioData() mimeType = %q, want %q", mimeType, "audio/pcm")
+	}
+
+	if len(data) != 3 || data[0] != 0x01 || data[1] != 0x02 || data[2] != 0x03 {
+		t.Fatalf("extractAudioData() data = %v, want raw audio bytes", data)
+	}
+}
+
+func TestWriteGeminiAudioFileWritesWAV(t *testing.T) {
+	dir := t.TempDir()
+	outputFile := filepath.Join(dir, "output.wav")
+	pcmData := []byte{0x11, 0x22, 0x33, 0x44}
+
+	if err := writeGeminiAudioFile(outputFile, pcmData, "audio/pcm"); err != nil {
+		t.Fatalf("writeGeminiAudioFile() unexpected error: %v", err)
+	}
+
+	fileData, err := os.ReadFile(outputFile)
+	if err != nil {
+		t.Fatalf("ReadFile() unexpected error: %v", err)
+	}
+
+	if !strings.HasPrefix(string(fileData[:4]), "RIFF") {
+		t.Fatalf("output file does not look like WAV data: %q", fileData[:4])
+	}
+
+	if got, want := len(fileData), 44+len(pcmData); got != want {
+		t.Fatalf("len(output) = %d, want %d", got, want)
+	}
+}