Add form builder (#235)

* add form builder

* cover VariImage

* test for closing errors

* simplify tests

* add audio api test coverage

* don't leak authToken when printed

* rename api->client

* fix test

image_test.go

@@ -1,7 +1,6 @@
-package openai_test
+package openai //nolint:testpackage // testing private field
 
 import (
-	. "github.com/sashabaranov/go-openai"
 	"github.com/sashabaranov/go-openai/internal/test"
 	"github.com/sashabaranov/go-openai/internal/test/checks"
 
@@ -259,3 +258,136 @@ func handleVariateImageEndpoint(w http.ResponseWriter, r *http.Request) {
 	resBytes, _ = json.Marshal(responses)
 	fmt.Fprintln(w, string(resBytes))
 }
+
+type mockFormBuilder struct {
+	mockCreateFormFile func(string, *os.File) error
+	mockWriteField     func(string, string) error
+	mockClose          func() error
+}
+
+func (fb *mockFormBuilder) createFormFile(fieldname string, file *os.File) error {
+	return fb.mockCreateFormFile(fieldname, file)
+}
+
+func (fb *mockFormBuilder) writeField(fieldname, value string) error {
+	return fb.mockWriteField(fieldname, value)
+}
+
+func (fb *mockFormBuilder) close() error {
+	return fb.mockClose()
+}
+
+func (fb *mockFormBuilder) formDataContentType() string {
+	return ""
+}
+
+func TestImageFormBuilderFailures(t *testing.T) {
+	config := DefaultConfig("")
+	config.BaseURL = ""
+	client := NewClientWithConfig(config)
+
+	mockBuilder := &mockFormBuilder{}
+	client.createFormBuilder = func(io.Writer) formBuilder {
+		return mockBuilder
+	}
+	ctx := context.Background()
+
+	req := ImageEditRequest{
+		Mask: &os.File{},
+	}
+
+	mockFailedErr := fmt.Errorf("mock form builder fail")
+	mockBuilder.mockCreateFormFile = func(string, *os.File) error {
+		return mockFailedErr
+	}
+	_, err := client.CreateEditImage(ctx, req)
+	checks.ErrorIs(t, err, mockFailedErr, "CreateImage should return error if form builder fails")
+
+	mockBuilder.mockCreateFormFile = func(name string, file *os.File) error {
+		if name == "mask" {
+			return mockFailedErr
+		}
+		return nil
+	}
+	_, err = client.CreateEditImage(ctx, req)
+	checks.ErrorIs(t, err, mockFailedErr, "CreateImage should return error if form builder fails")
+
+	mockBuilder.mockCreateFormFile = func(name string, file *os.File) error {
+		return nil
+	}
+
+	var failForField string
+	mockBuilder.mockWriteField = func(fieldname, value string) error {
+		if fieldname == failForField {
+			return mockFailedErr
+		}
+		return nil
+	}
+
+	failForField = "prompt"
+	_, err = client.CreateEditImage(ctx, req)
+	checks.ErrorIs(t, err, mockFailedErr, "CreateImage should return error if form builder fails")
+
+	failForField = "n"
+	_, err = client.CreateEditImage(ctx, req)
+	checks.ErrorIs(t, err, mockFailedErr, "CreateImage should return error if form builder fails")
+
+	failForField = "size"
+	_, err = client.CreateEditImage(ctx, req)
+	checks.ErrorIs(t, err, mockFailedErr, "CreateImage should return error if form builder fails")
+
+	failForField = ""
+	mockBuilder.mockClose = func() error {
+		return mockFailedErr
+	}
+	_, err = client.CreateEditImage(ctx, req)
+	checks.ErrorIs(t, err, mockFailedErr, "CreateImage should return error if form builder fails")
+}
+
+func TestVariImageFormBuilderFailures(t *testing.T) {
+	config := DefaultConfig("")
+	config.BaseURL = ""
+	client := NewClientWithConfig(config)
+
+	mockBuilder := &mockFormBuilder{}
+	client.createFormBuilder = func(io.Writer) formBuilder {
+		return mockBuilder
+	}
+	ctx := context.Background()
+
+	req := ImageVariRequest{}
+
+	mockFailedErr := fmt.Errorf("mock form builder fail")
+	mockBuilder.mockCreateFormFile = func(string, *os.File) error {
+		return mockFailedErr
+	}
+	_, err := client.CreateVariImage(ctx, req)
+	checks.ErrorIs(t, err, mockFailedErr, "CreateVariImage should return error if form builder fails")
+
+	mockBuilder.mockCreateFormFile = func(name string, file *os.File) error {
+		return nil
+	}
+
+	var failForField string
+	mockBuilder.mockWriteField = func(fieldname, value string) error {
+		if fieldname == failForField {
+			return mockFailedErr
+		}
+		return nil
+	}
+
+	failForField = "n"
+	_, err = client.CreateVariImage(ctx, req)
+	checks.ErrorIs(t, err, mockFailedErr, "CreateVariImage should return error if form builder fails")
+
+	failForField = "size"
+	_, err = client.CreateVariImage(ctx, req)
+	checks.ErrorIs(t, err, mockFailedErr, "CreateVariImage should return error if form builder fails")
+
+	failForField = ""
+	mockBuilder.mockClose = func() error {
+		return mockFailedErr
+	}
+	_, err = client.CreateVariImage(ctx, req)
+	checks.ErrorIs(t, err, mockFailedErr, "CreateImage should return error if form builder fails")
+}