test: add test for firestore client adapter

src/database/firestore/client.go

@@ -9,16 +9,38 @@ import (
 	"github.com/dorianneto/url-shortener/src/database/output/document"
 )
 
+type documentAdapterInterface interface {
+	Get(ctx context.Context) (_ *firestore.DocumentSnapshot, err error)
+	Set(ctx context.Context, data interface{}, opts ...firestore.SetOption) (_ *firestore.WriteResult, err error)
+}
+
+type FirestoreClientAdapterInterface interface {
+	Doc(path string) documentAdapterInterface
+	Close() error
+}
+
+type firestoreClientAdapter struct {
+	client *firestore.Client
+}
+
+func (fca *firestoreClientAdapter) Close() error {
+	return fca.client.Close()
+}
+
+func (fca *firestoreClientAdapter) Doc(path string) documentAdapterInterface {
+	return fca.client.Doc(path)
+}
+
 type firestoreAdapter struct {
-	client            *firestore.Client
+	client            FirestoreClientAdapterInterface
 	contextBackground context.Context
 }
 
 func NewFirestoreAdapter() *firestoreAdapter {
 	return &firestoreAdapter{}
 }
 
-func (fa *firestoreAdapter) getClient() *firestore.Client {
+func (fa *firestoreAdapter) getClient() FirestoreClientAdapterInterface {
 	if fa.client != nil {
 		return fa.client
 	}
@@ -29,7 +51,9 @@ func (fa *firestoreAdapter) getClient() *firestore.Client {
 		log.Fatalln(err)
 	}
 
-	fa.client = client
+	fa.client = &firestoreClientAdapter{
+		client: client,
+	}
 
 	return fa.client
 }

src/database/firestore/client_test.go

@@ -0,0 +1,133 @@
+package firestore
+
+import (
+	"context"
+	"errors"
+	"reflect"
+	"testing"
+
+	"cloud.google.com/go/firestore"
+)
+
+var (
+	haveCloseBeenCalled = false
+	getFn, setFn        func() error
+)
+
+type documentAdapterMock struct{}
+
+func (a *documentAdapterMock) Get(ctx context.Context) (_ *firestore.DocumentSnapshot, err error) {
+	return &firestore.DocumentSnapshot{}, getFn()
+}
+
+func (a *documentAdapterMock) Set(ctx context.Context, data interface{}, opts ...firestore.SetOption) (_ *firestore.WriteResult, err error) {
+	return nil, setFn()
+}
+
+type clientAdapterMock struct{}
+
+func (c *clientAdapterMock) Doc(path string) documentAdapterInterface {
+	return &documentAdapterMock{}
+}
+
+func (c *clientAdapterMock) Close() error {
+	haveCloseBeenCalled = true
+	return nil
+}
+
+func resetMocks() {
+	haveCloseBeenCalled = false
+	getFn = func() error {
+		return nil
+	}
+	setFn = func() error {
+		return nil
+	}
+}
+
+func TestClientClose(t *testing.T) {
+	defer t.Cleanup(resetMocks)
+
+	c := NewFirestoreAdapter()
+	c.client = &clientAdapterMock{}
+
+	c.Close()
+
+	if !haveCloseBeenCalled {
+		t.Error("Method Close() is expected to be called")
+	}
+}
+
+func TestClientRead(t *testing.T) {
+	defer t.Cleanup(resetMocks)
+
+	c := NewFirestoreAdapter()
+	c.client = &clientAdapterMock{}
+
+	got, err := c.Read("foo")
+
+	if err != nil {
+		t.Errorf("An error is not expected")
+	}
+
+	if reflect.TypeOf(got).String() != "*document.ReadOutput" {
+		t.Error("The return expected to be instance of *document.ReadOutput")
+	}
+}
+
+func TestClientCannotReadBecauseBecauseSomethingGoesWrong(t *testing.T) {
+	defer t.Cleanup(resetMocks)
+
+	getFn = func() error {
+		return errors.New("something goes wrong")
+	}
+
+	c := NewFirestoreAdapter()
+	c.client = &clientAdapterMock{}
+
+	got, err := c.Read("foo")
+
+	if err == nil {
+		t.Errorf("An error is expected")
+	}
+
+	if got != nil {
+		t.Error("The return expected to be nil")
+	}
+}
+
+func TestClientWrite(t *testing.T) {
+	defer t.Cleanup(resetMocks)
+
+	c := NewFirestoreAdapter()
+	c.client = &clientAdapterMock{}
+
+	got, err := c.Write("foo", map[string]int{"foo": 1, "bar": 2})
+
+	if err != nil {
+		t.Errorf("An error is not expected")
+	}
+
+	_, ok := got.(map[string]int)
+
+	if !ok {
+		t.Error("The return expected to be map[string]int")
+	}
+}
+
+func TestClientCannotWriteBecauseSomethingGoesWrong(t *testing.T) {
+	defer t.Cleanup(resetMocks)
+
+	setFn = func() error {
+		return errors.New("something goes wrong")
+	}
+
+	c := NewFirestoreAdapter()
+	c.client = &clientAdapterMock{}
+
+	_, err := c.Write("foo", nil)
+
+	if err == nil {
+		t.Errorf("An error is expected")
+	}
+}