Add tests for paster

go.mod

@@ -18,6 +18,7 @@ require (
 	github.com/pressly/goose v2.4.5+incompatible // indirect
 	github.com/rogpeppe/go-internal v1.2.2 // indirect
 	github.com/sirupsen/logrus v1.3.0
+	github.com/stretchr/testify v1.3.0
 	github.com/ziutek/mymysql v1.5.4 // indirect
 	golang.org/x/crypto v0.0.0-20190222235706-ffb98f73852f // indirect
 	golang.org/x/sys v0.0.0-20190222171317-cd391775e71e // indirect

go.sum

@@ -419,6 +419,7 @@ github.com/spf13/pflag v1.0.3/go.mod h1:DYY7MBk1bdzusC3SYhjObp+wFpr4gzcvqqNjLnIn
 github.com/spf13/viper v1.2.1/go.mod h1:P4AexN0a+C9tGAnUFNwDMYYZv3pjFuvmeiMyKRaNVlI=
 github.com/spf13/viper v1.3.1/go.mod h1:ZiWeW+zYFKm7srdB9IoDzzZXaJaI5eL9QjNiN/DMA2s=
 github.com/stretchr/objx v0.1.0/go.mod h1:HFkY916IF+rwdDfMAkV7OtwuqBVzrE8GR6GFx+wExME=
+github.com/stretchr/objx v0.1.1 h1:2vfRuCMp5sSVIDSqO8oNnWJq7mPa6KVP3iPIwFBuy8A=
 github.com/stretchr/objx v0.1.1/go.mod h1:HFkY916IF+rwdDfMAkV7OtwuqBVzrE8GR6GFx+wExME=
 github.com/stretchr/testify v1.2.2/go.mod h1:a8OnRcib4nhh0OaRAV+Yts87kKdq0PP7pXfy6kDkUVs=
 github.com/stretchr/testify v1.3.0 h1:TivCn/peBQ7UY8ooIcPgZFpTNSz0Q2U6UrFlUfqbe0Q=

handler/paster_test.go

@@ -0,0 +1,93 @@
+package handler
+
+import (
+	"testing"
+
+	"github.com/google/uuid"
+	"github.com/ollien/updown/repository"
+	"github.com/stretchr/testify/mock"
+)
+
+type MockFile struct {
+	mock.Mock
+}
+
+func (file *MockFile) Read(buffer []byte) (int, error) {
+	args := file.Called(buffer)
+
+	return args.Int(0), args.Error(1)
+}
+
+func (file *MockFile) Write(buffer []byte) (int, error) {
+	args := file.Called(buffer)
+
+	return args.Int(0), args.Error(1)
+}
+
+func (file *MockFile) Seek(offset int64, whence int) (int64, error) {
+	args := file.Called(offset, whence)
+
+	return args.Get(0).(int64), args.Error(1)
+}
+
+func (file *MockFile) Close() error {
+	args := file.Called()
+
+	return args.Error(0)
+}
+
+func setupPaster() Paster {
+	paste := repository.Paste{
+		ID:     23,
+		Handle: uuid.Nil,
+		Title:  "Test post",
+	}
+
+	return Paster{
+		Paste: paste,
+		file:  &MockFile{},
+	}
+}
+
+func TestRead(t *testing.T) {
+	paster := setupPaster()
+	mockFile := paster.file.(*MockFile)
+
+	buffer := make([]byte, 5)
+	mockFile.On("Read", buffer).Return(len(buffer), nil).Once()
+	// Ensure we seek to the start of the file
+	mockFile.On("Seek", int64(0), 0).Return(int64(0), nil).Once()
+	mockFile.AssertNotCalled(t, "Close")
+	mockFile.AssertNotCalled(t, "Write")
+
+	paster.Read(buffer)
+	mockFile.AssertExpectations(t)
+}
+
+func TestWrite(t *testing.T) {
+	paster := setupPaster()
+	mockFile := paster.file.(*MockFile)
+
+	testPaste := []byte("hello world")
+	mockFile.On("Write", testPaste).Return(len(testPaste), nil).Once()
+	// Ensure we seek to the start of the file
+	mockFile.On("Seek", int64(0), 0).Return(int64(0), nil).Once()
+	mockFile.AssertNotCalled(t, "Close")
+
+	paster.Write(testPaste)
+	mockFile.AssertExpectations(t)
+}
+
+func TestClose(t *testing.T) {
+	paster := setupPaster()
+	mockFile := paster.file.(*MockFile)
+
+	mockFile.On("Close").Return(nil).Once()
+	mockFile.AssertNotCalled(t, "Close")
+	mockFile.AssertNotCalled(t, "Seek")
+	mockFile.AssertNotCalled(t, "Read")
+	// If we write to the file on close, that isn't the worst thing in the world and we won't enforce it being a problem
+
+	paster.Close()
+	mockFile.AssertExpectations(t)
+}