twitter: add GetTweets method

config/config.go

@@ -6,7 +6,7 @@ import (
 )
 
 type TwitterConfig struct {
-	ClientID, ClientSecret, CallbackURL, AuthorizeURL, TokenURL string
+	BearerToken, ClientID, ClientSecret, CallbackURL, AuthorizeURL, TokenURL string
 }
 type Config struct {
 	DatabaseURL string
@@ -29,6 +29,7 @@ func NewFromEnv() (Config, error) {
 		SessionKey:  sessionKey,
 		ListenAddr:  listenAddr,
 		Twitter: TwitterConfig{
+			BearerToken:  os.Getenv("ELON_TWITTER_BEARER_TOKEN"),
 			ClientID:     os.Getenv("ELON_TWITTER_CLIENT_ID"),
 			ClientSecret: os.Getenv("ELON_TWITTER_CLIENT_SECRET"),
 			CallbackURL:  os.Getenv("ELON_TWITTER_CALLBACK_URL"),

generated/mocks/Getter.go

@@ -0,0 +1,48 @@
+// Code generated by mockery v2.12.2. DO NOT EDIT.
+
+package mocks
+
+import (
+	http "net/http"
+	testing "testing"
+
+	mock "github.com/stretchr/testify/mock"
+)
+
+// Getter is an autogenerated mock type for the Getter type
+type Getter struct {
+	mock.Mock
+}
+
+// Get provides a mock function with given fields: _a0
+func (_m *Getter) Get(_a0 string) (*http.Response, error) {
+	ret := _m.Called(_a0)
+
+	var r0 *http.Response
+	if rf, ok := ret.Get(0).(func(string) *http.Response); ok {
+		r0 = rf(_a0)
+	} else {
+		if ret.Get(0) != nil {
+			r0 = ret.Get(0).(*http.Response)
+		}
+	}
+
+	var r1 error
+	if rf, ok := ret.Get(1).(func(string) error); ok {
+		r1 = rf(_a0)
+	} else {
+		r1 = ret.Error(1)
+	}
+
+	return r0, r1
+}
+
+// NewGetter creates a new instance of Getter. It also registers the testing.TB interface on the mock and a cleanup function to assert the mocks expectations.
+func NewGetter(t testing.TB) *Getter {
+	mock := &Getter{}
+	mock.Mock.Test(t)
+
+	t.Cleanup(func() { mock.AssertExpectations(t) })
+
+	return mock
+}

twitter/api.go

@@ -1,32 +1,87 @@
 package twitter
 
+//go:generate mockery --recursive --name Getter --output ../generated/mocks
+
 import (
 	"encoding/json"
 	"fmt"
 	"net/http"
+	"time"
 )
 
+// ElonID is the Twitter ID of @elonmusk.
+const ElonID = "44196397"
+
+// User represents a Twitter user.
 type User struct {
 	ID       string
 	Name     string
 	Username string
 }
 
-func NewAPIClient(httpclient *http.Client) *APIClient {
+// Tweet represents a tweet.
+type Tweet struct {
+	ID   string
+	Text string
+}
+
+// bearerTokenTransport implements http.RoundTripper.
+type bearerTokenTransport struct {
+	bearerToken string
+}
+
+// RoundTrip sets the Authorization header with the provided bearerToken, and
+// forwards the request. It will panic if the request includes a body (which
+// requires special handling).
+func (t *bearerTokenTransport) RoundTrip(req *http.Request) (*http.Response, error) {
+	if req.Body != nil {
+		panic("bearerTokenTransport does not handle requests with non-nil body")
+	}
+	req2 := cloneRequest(req)
+	req2.Header.Set("Authorization", "Bearer "+t.bearerToken)
+	return http.DefaultTransport.RoundTrip(req2)
+}
+
+// https://go.googlesource.com/oauth2/+/f95fa95eaa936d9d87489b15d1d18b97c1ba9c28/transport.go#96
+func cloneRequest(r *http.Request) *http.Request {
+	// shallow copy of the struct
+	r2 := new(http.Request)
+	*r2 = *r
+	// deep copy of the Header
+	r2.Header = make(http.Header, len(r.Header))
+	for k, s := range r.Header {
+		r2.Header[k] = append([]string(nil), s...)
+	}
+	return r2
+}
+
+type Getter interface {
+	Get(string) (*http.Response, error)
+}
+
+// NewAPIClient returns a new APIClient.
+func NewAPIClient(httpclient Getter) *APIClient {
 	return &APIClient{httpclient}
 }
 
-type APIClient struct {
-	*http.Client
+// NewAPIClient returns a new APIClient which will authenticate with the
+// provided bearer token.
+func NewAPIClientWithBearerToken(bearerToken string) *APIClient {
+	return &APIClient{&http.Client{
+		Timeout:   time.Second * 5,
+		Transport: &bearerTokenTransport{bearerToken: bearerToken},
+	}}
 }
 
+// APIClient interacts with the Twitter API V2.
+type APIClient struct {
+	Getter
+}
+
+// GetMe returns the currently authenticated user.
 func (c *APIClient) GetMe() (*User, error) {
 	type oauthResponse struct {
-		Data struct {
-			ID       string `json:"id"`
-			Name     string `json:"name"`
-			Username string `json:"username"`
-		} `json:"data"`
+		Data *User `json:"data"`
 	}
 
 	resp, err := c.Get("https://api.twitter.com/2/users/me")
@@ -43,9 +98,28 @@ func (c *APIClient) GetMe() (*User, error) {
 		return nil, fmt.Errorf("error decoding resource: %v", err)
 	}
 
-	return &User{
-		ID:       oauthResp.Data.ID,
-		Name:     oauthResp.Data.Name,
-		Username: oauthResp.Data.Username,
-	}, nil
+	return oauthResp.Data, nil
+}
+
+// GetElonTweets returns the latest tweets for a given user.
+func (c *APIClient) GetTweets(userID string, sinceID string) ([]*Tweet, error) {
+	type oauthResponse struct {
+		Data []*Tweet `json:"data"`
+	}
+
+	resp, err := c.Get(fmt.Sprintf("https://api.twitter.com/2/users/%s/tweets?since_id=%s", userID, sinceID))
+	if err != nil {
+		return nil, fmt.Errorf("error fetching resource: %v", err)
+	}
+	defer resp.Body.Close()
+	if resp.StatusCode != http.StatusOK {
+		return nil, fmt.Errorf("error fetching resource: status code %d", resp.StatusCode)
+	}
+
+	var oauthResp oauthResponse
+	if err = json.NewDecoder(resp.Body).Decode(&oauthResp); err != nil {
+		return nil, fmt.Errorf("error decoding resource: %v", err)
+	}
+
+	return oauthResp.Data, nil
 }

twitter/api_test.go

@@ -0,0 +1,119 @@
+package twitter_test
+
+import (
+	"io"
+	"net/http"
+	"strings"
+	"testing"
+
+	"git.netflux.io/rob/elon-eats-my-tweets/generated/mocks"
+	"git.netflux.io/rob/elon-eats-my-tweets/twitter"
+	"github.com/stretchr/testify/assert"
+)
+
+func TestGetMe(t *testing.T) {
+	testCases := []struct {
+		name               string
+		responseStatusCode int
+		responseBody       io.Reader
+		wantUser           *twitter.User
+		wantErr            string
+	}{
+		{
+			name:               "successful request",
+			responseStatusCode: 200,
+			responseBody:       strings.NewReader(`{"Data": {"id": "1", "name": "foo", "username": "foo bar"}}`),
+			wantUser:           &twitter.User{ID: "1", Name: "foo", Username: "foo bar"},
+		},
+		{
+			name:               "500 response",
+			responseStatusCode: 500,
+			responseBody:       strings.NewReader("whale"),
+			wantUser:           nil,
+			wantErr:            "error fetching resource: status code 500",
+		},
+		{
+			name:               "decoder error",
+			responseStatusCode: 200,
+			responseBody:       strings.NewReader("<html></html>"),
+			wantUser:           nil,
+			wantErr:            "error decoding resource: invalid character '<' looking for beginning of value",
+		},
+	}
+
+	for _, tc := range testCases {
+		t.Run(tc.name, func(t *testing.T) {
+			var getter mocks.Getter
+			getter.
+				On("Get", "https://api.twitter.com/2/users/me").
+				Return(&http.Response{StatusCode: tc.responseStatusCode, Body: io.NopCloser(tc.responseBody)}, nil)
+			client := twitter.NewAPIClient(&getter)
+
+			user, err := client.GetMe()
+			assert.Equal(t, tc.wantUser, user)
+
+			if tc.wantErr == "" {
+				assert.NoError(t, err)
+			} else {
+				assert.EqualError(t, err, tc.wantErr)
+			}
+		})
+	}
+}
+
+func TestGetTweets(t *testing.T) {
+	testCases := []struct {
+		name               string
+		userID, sinceID    string
+		responseStatusCode int
+		responseBody       io.Reader
+		wantTweets         []*twitter.Tweet
+		wantErr            string
+	}{
+		{
+			name:               "successful request",
+			userID:             "1",
+			sinceID:            "1000",
+			responseStatusCode: 200,
+			responseBody:       strings.NewReader(`{"Data": [{"id": "101", "text": "foo"}, {"id": "102", "text": "bar"}]}`),
+			wantTweets:         []*twitter.Tweet{{ID: "101", Text: "foo"}, {ID: "102", Text: "bar"}},
+		},
+		{
+			name:               "500 response",
+			userID:             "1",
+			sinceID:            "1000",
+			responseStatusCode: 500,
+			responseBody:       strings.NewReader("whale"),
+			wantTweets:         nil,
+			wantErr:            "error fetching resource: status code 500",
+		},
+		{
+			name:               "decoder error",
+			userID:             "1",
+			sinceID:            "1000",
+			responseStatusCode: 200,
+			responseBody:       strings.NewReader("<html></html>"),
+			wantTweets:         nil,
+			wantErr:            "error decoding resource: invalid character '<' looking for beginning of value",
+		},
+	}
+
+	for _, tc := range testCases {
+		t.Run(tc.name, func(t *testing.T) {
+			var getter mocks.Getter
+			getter.
+				On("Get", "https://api.twitter.com/2/users/"+tc.userID+"/tweets?since_id="+tc.sinceID).
+				Return(&http.Response{StatusCode: tc.responseStatusCode, Body: io.NopCloser(tc.responseBody)}, nil)
+			client := twitter.NewAPIClient(&getter)
+
+			tweets, err := client.GetTweets(tc.userID, tc.sinceID)
+			assert.Equal(t, tc.wantTweets, tweets)
+
+			if tc.wantErr == "" {
+				assert.NoError(t, err)
+			} else {
+				assert.EqualError(t, err, tc.wantErr)
+			}
+		})
+	}
+}