Merge pull request #557 from runnerdave/puppy_store_error_handling

Puppy store error handling

07_errors/runnerdave/errors.go

@@ -0,0 +1,35 @@
+package main
+
+import "fmt"
+
+// Error codes
+const (
+	// ErrUnknown is used when an unknown error occurred
+	ErrUnknown uint16 = iota
+	// ErrInvalidValue is used when the value for the puppy is negative
+	ErrInvalidValue
+	// ErrIDNotFound is used when attempting to read a non-existing entry
+	ErrIDNotFound
+)
+
+// Error struct to identify errors in Puppy store
+type Error struct {
+	Code    uint16 `json:"code"`
+	Message string `json:"message"`
+}
+
+func (e *Error) Error() string {
+	return fmt.Sprintf("%d: %s", e.Code, e.Message)
+}
+
+// Errorf creates a new Error with formatting
+func Errorf(code uint16, format string, args ...interface{}) *Error {
+	return &Error{code, fmt.Sprintf(format, args...)}
+}
+
+func validateValue(value float32) error {
+	if value < 0 {
+		return Errorf(ErrInvalidValue, "puppy has invalid value (%f)", value)
+	}
+	return nil
+}

07_errors/runnerdave/main.go

@@ -0,0 +1,30 @@
+package main
+
+import (
+	"fmt"
+	"io"
+	"os"
+)
+
+var out io.Writer = os.Stdout
+
+func main() {
+	puppy1 := Puppy{ID: 11, Breed: "Chihuahua", Colour: "Brown", Value: 12.30}
+	puppy2 := Puppy{ID: 11, Breed: "Chihuahua", Colour: "Brown", Value: 10.30}
+
+	mapStore := NewMapStore()
+	mapCreateErr := mapStore.CreatePuppy(&puppy1)
+
+	puppyMap, _ := mapStore.ReadPuppy(11)
+	fmt.Fprintf(out, "Puppy created in map of Breed:%s, errors at creation:%v\n", puppyMap.Breed, mapCreateErr)
+
+	syncStore := NewSyncStore()
+	syncCreateErr := syncStore.CreatePuppy(&puppy1)
+	syncUpdateErr := syncStore.UpdatePuppy(11, &puppy2)
+	puppySync, _ := syncStore.ReadPuppy(11)
+	fmt.Fprintf(out, "Puppy created in sync of Breed:%s, value updated to:%f, error at creation:%v, error in update:%v\n",
+		puppySync.Breed, puppySync.Value, syncCreateErr, syncUpdateErr)
+
+	puppyMap, err := mapStore.ReadPuppy(12)
+	fmt.Fprint(out, err)
+}

07_errors/runnerdave/main_test.go

@@ -0,0 +1,25 @@
+package main
+
+import (
+	"bytes"
+	"strconv"
+	"testing"
+)
+
+func TestMainOutput(t *testing.T) {
+	var buf bytes.Buffer
+	out = &buf
+
+	main()
+
+	expected := strconv.Quote(`Puppy created in map of Breed:Chihuahua, errors at creation:<nil>
+Puppy created in sync of Breed:Chihuahua, value updated to:10.300000, error at creation:<nil>, error in update:<nil>
+2: puppy with ID:12 not found`)
+	actual := strconv.Quote(buf.String())
+	t.Logf("expected:%s", expected)
+	t.Logf("actual:%s", actual)
+
+	if expected != actual {
+		t.Errorf("Unexpected output in main()")
+	}
+}

07_errors/runnerdave/map_store.go

@@ -0,0 +1,52 @@
+package main
+
+// MapStore represents a simple map storage for the Puppy store
+type MapStore struct {
+	puppies map[uint16]Puppy
+}
+
+// NewMapStore creates a new in-memory store with map intialised
+func NewMapStore() *MapStore {
+	return &MapStore{puppies: map[uint16]Puppy{}}
+}
+
+// CreatePuppy saves new puppy if not in store, if it is already returns error
+func (m *MapStore) CreatePuppy(p *Puppy) error {
+	if err := validateValue(p.Value); err != nil {
+		return err
+	}
+	if _, ok := m.puppies[p.ID]; ok {
+		return Errorf(ErrUnknown, "puppy with id %d already exists", p.ID)
+	}
+	m.puppies[p.ID] = *p
+	return nil
+}
+
+// ReadPuppy reads store by Puppy ID
+func (m *MapStore) ReadPuppy(id uint16) (Puppy, error) {
+	if puppy, ok := m.puppies[id]; ok {
+		return puppy, nil
+	}
+	return Puppy{}, Errorf(ErrIDNotFound, "puppy with ID:%d not found", id)
+}
+
+// UpdatePuppy updates puppy with new value if ID present otherwise error
+func (m *MapStore) UpdatePuppy(id uint16, p *Puppy) error {
+	if err := validateValue(p.Value); err != nil {
+		return err
+	}
+	if _, ok := m.puppies[id]; !ok {
+		return Errorf(ErrIDNotFound, "puppy with ID:%d not found", id)
+	}
+	m.puppies[id] = *p
+	return nil
+}
+
+// DeletePuppy deletes a puppy by id from the store
+func (m *MapStore) DeletePuppy(id uint16) error {
+	if _, ok := m.puppies[id]; ok {
+		delete(m.puppies, id)
+		return nil
+	}
+	return Errorf(ErrIDNotFound, "puppy with ID:%d not found", id)
+}

07_errors/runnerdave/storer_test.go

@@ -0,0 +1,193 @@
+package main
+
+import (
+	"testing"
+
+	tassert "github.com/stretchr/testify/assert"
+	"github.com/stretchr/testify/require"
+	"github.com/stretchr/testify/suite"
+)
+
+var (
+	puppy1 = func() Puppy {
+		return Puppy{ID: 11, Breed: "Chihuahua", Colour: "Brown", Value: 12.30}
+	}
+	puppy2 = func() Puppy {
+		return Puppy{ID: 12, Breed: "Cacri", Colour: "Undefined", Value: 1.30}
+	}
+	puppy3 = func() Puppy {
+		return Puppy{ID: 12, Breed: "Imaginary", Colour: "Undefined", Value: -1.30}
+	}
+)
+
+type storerSuite struct {
+	suite.Suite
+	store      Storer
+	storerType func() Storer
+}
+
+func (s *storerSuite) TestUpdatePuppyIDDoesNotExist() {
+	// given
+	assert := tassert.New(s.T())
+	testPuppy := puppy1()
+
+	// when
+	err := s.store.UpdatePuppy(13, &testPuppy)
+
+	// then
+	assert.Error(err, "Should produce an error if id not found")
+	serr, ok := err.(*Error)
+	assert.True(ok)
+	assert.Equal(uint16(0x2), serr.Code)
+}
+
+func (s *storerSuite) TestUpdatePuppy() {
+	// given
+	assert := tassert.New(s.T())
+	testPuppy := puppy1()
+	targetPuppy := puppy2()
+	cerr := s.store.CreatePuppy(&testPuppy)
+	r := require.New(s.T())
+	r.NoError(cerr, "Create should not produce an error")
+
+	// when
+	uerr := s.store.UpdatePuppy(11, &targetPuppy)
+
+	// then
+	r.NoError(uerr, "Should be able to update store")
+	updatedPuppy, err := s.store.ReadPuppy(11)
+	r.NoError(err, "Should be able to read updated puppy")
+	assert.Equal(targetPuppy, updatedPuppy, "Updated puppy should be equal to puppy2")
+}
+
+func (s *storerSuite) TestReadPuppy() {
+	// given
+	assert := tassert.New(s.T())
+	testPuppy := puppy1()
+	cerr := s.store.CreatePuppy(&testPuppy)
+	r := require.New(s.T())
+	r.NoError(cerr, "Create should not produce an error")
+
+	// when
+	newPuppy, err := s.store.ReadPuppy(11)
+
+	// then
+	r.NoError(err, "Should be able to read a newly added puppy")
+	assert.Equal(testPuppy, newPuppy, "Newly added puppy should be equal to test puppy")
+}
+
+func (s *storerSuite) TestReadNonExistingPuppy() {
+	// given
+	assert := tassert.New(s.T())
+	r := require.New(s.T())
+
+	// when
+	_, err := s.store.ReadPuppy(12)
+
+	// then
+	r.Error(err, "Should produce an error when puppy is not found")
+	serr, ok := err.(*Error)
+	assert.True(ok)
+	assert.Equal(uint16(0x2), serr.Code)
+}
+
+func (s *storerSuite) TestDeletePuppy() {
+	// given
+	assert := tassert.New(s.T())
+	testPuppy := puppy1()
+	cerr := s.store.CreatePuppy(&testPuppy)
+	r := require.New(s.T())
+	r.NoError(cerr, "Create should not produce an error")
+
+	// when
+	err := s.store.DeletePuppy(11)
+
+	// then
+	r.NoError(err, "Should be able to delete a newly added puppy")
+	_, rerr := s.store.ReadPuppy(11)
+	serr, ok := rerr.(*Error)
+	assert.True(ok)
+	assert.Equal(uint16(0x2), serr.Code)
+}
+
+func (s *storerSuite) TestDeleteNonExistingPuppy() {
+	// given
+	assert := tassert.New(s.T())
+	r := require.New(s.T())
+
+	// when
+	err := s.store.DeletePuppy(11)
+
+	// then
+	r.Error(err, "Should not be able to delete a non existing puppy")
+	serr, ok := err.(*Error)
+	assert.True(ok)
+	assert.Equal(uint16(0x2), serr.Code)
+}
+
+func (s *storerSuite) TestCreateExistingPuppy() {
+	// given
+	assert := tassert.New(s.T())
+	testPuppy := puppy1()
+	cerr := s.store.CreatePuppy(&testPuppy)
+	r := require.New(s.T())
+	r.NoError(cerr, "Create should not produce an error")
+
+	// when
+	err := s.store.CreatePuppy(&testPuppy)
+
+	// then
+	assert.Error(err, "Should not be able to create twice a the same puppy")
+}
+
+func (s *storerSuite) TestCreatePuppyWithInvalidValue() {
+	// given
+	assert := tassert.New(s.T())
+	testPuppy := puppy3()
+	r := require.New(s.T())
+
+	// when
+	createError := s.store.CreatePuppy(&testPuppy)
+
+	// then
+	r.Error(createError, "Should not allow to create a puppy with invalid value")
+	serr, ok := createError.(*Error)
+	assert.True(ok)
+	assert.Equal(uint16(0x1), serr.Code)
+}
+
+func (s *storerSuite) TestUpdatePuppyWithInvalidValue() {
+	// given
+	assert := tassert.New(s.T())
+	testPuppy := puppy1()
+	updatePuppy := puppy3()
+	createError := s.store.CreatePuppy(&testPuppy)
+	r := require.New(s.T())
+	r.NoError(createError, "Create should not produce an error")
+
+	// when
+	uerr := s.store.UpdatePuppy(11, &updatePuppy)
+
+	// then
+	r.Error(uerr, "Should not allow to update a puppy with invalid value")
+	serr, ok := uerr.(*Error)
+	assert.True(ok)
+	assert.Equal(uint16(0x1), serr.Code)
+}
+
+func (s *storerSuite) SetupTest() {
+	s.store = s.storerType()
+}
+
+func TestStorer(t *testing.T) {
+	syncSuite := storerSuite{
+		store:      NewSyncStore(),
+		storerType: func() Storer { return NewSyncStore() },
+	}
+	mapSuite := storerSuite{
+		store:      NewMapStore(),
+		storerType: func() Storer { return NewMapStore() },
+	}
+	suite.Run(t, &syncSuite)
+	suite.Run(t, &mapSuite)
+}