github: implement github directory provider (#963)

* github: implement github directory provider

* fix test

internal/directory/github/github_test.go

@@ -0,0 +1,112 @@
+package github
+
+import (
+	"context"
+	"encoding/json"
+	"net/http"
+	"net/http/httptest"
+	"net/url"
+	"testing"
+
+	"github.com/go-chi/chi"
+	"github.com/go-chi/chi/middleware"
+	"github.com/stretchr/testify/assert"
+
+	"github.com/pomerium/pomerium/internal/testutil"
+)
+
+type M = map[string]interface{}
+
+func newMockAPI(t *testing.T, srv *httptest.Server) http.Handler {
+	r := chi.NewRouter()
+	r.Use(middleware.Logger)
+	r.Use(func(next http.Handler) http.Handler {
+		return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+			if !assert.Equal(t, "Basic YWJjOnh5eg==", r.Header.Get("Authorization")) {
+				http.Error(w, "forbidden", http.StatusForbidden)
+				return
+			}
+			next.ServeHTTP(w, r)
+		})
+	})
+	r.Get("/user/orgs", func(w http.ResponseWriter, r *http.Request) {
+		json.NewEncoder(w).Encode([]M{
+			{"login": "org1"},
+			{"login": "org2"},
+		})
+	})
+	r.Get("/orgs/{org_id}/teams", func(w http.ResponseWriter, r *http.Request) {
+		teams := map[string][]M{
+			"org1": {
+				{"slug": "team1"},
+				{"slug": "team2"},
+			},
+			"org2": {
+				{"slug": "team3"},
+				{"slug": "team4"},
+			},
+		}
+		orgID := chi.URLParam(r, "org_id")
+		json.NewEncoder(w).Encode(teams[orgID])
+	})
+	r.Get("/orgs/{org_id}/teams/{team_id}/members", func(w http.ResponseWriter, r *http.Request) {
+		members := map[string]map[string][]M{
+			"org1": {
+				"team1": {
+					{"login": "user1"},
+					{"login": "user2"},
+				},
+				"team2": {
+					{"login": "user1"},
+				},
+			},
+			"org2": {
+				"team3": {
+					{"login": "user1"},
+					{"login": "user2"},
+					{"login": "user3"},
+				},
+				"team4": {
+					{"login": "user4"},
+				},
+			},
+		}
+		orgID := chi.URLParam(r, "org_id")
+		teamID := chi.URLParam(r, "team_id")
+		json.NewEncoder(w).Encode(members[orgID][teamID])
+	})
+	return r
+}
+
+func Test(t *testing.T) {
+	var mockAPI http.Handler
+	srv := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		mockAPI.ServeHTTP(w, r)
+	}))
+	defer srv.Close()
+	mockAPI = newMockAPI(t, srv)
+
+	p := New(
+		WithURL(mustParseURL(srv.URL)),
+		WithServiceAccount(&ServiceAccount{
+			Username:            "abc",
+			PersonalAccessToken: "xyz",
+		}),
+	)
+	users, err := p.UserGroups(context.Background())
+	assert.NoError(t, err)
+	testutil.AssertProtoJSONEqual(t, `[
+		{ "id": "github/user1", "groups": ["team1", "team2", "team3"] },
+		{ "id": "github/user2", "groups": ["team1", "team3"] },
+		{ "id": "github/user3", "groups": ["team3"] },
+		{ "id": "github/user4", "groups": ["team4"] }
+	]`, users)
+}
+
+func mustParseURL(rawurl string) *url.URL {
+	u, err := url.Parse(rawurl)
+	if err != nil {
+		panic(err)
+	}
+	return u
+}