Review solo Heroku accounts via app collaborators

A personal Heroku account has no Team, so GET /teams returns an empty
list and the team-members path has nothing to fetch. Solo accounts
grant access per app, so enumerate the user's personal apps and collect
each app's owner plus its collaborators, deduped by Heroku user ID.

An empty teamID (or the reserved personal-account slug) now selects this
personal mode. Factor the Range/Next-Range pagination shared by the
members, apps, and collaborators endpoints into herokuListAll.

Signed-off-by: Aurélien Sibiril <81782+aureliensibiril@users.noreply.github.com>

pkg/accessreview/drivers/heroku_test.go

@@ -16,6 +16,8 @@ package drivers
 
 import (
 	"context"
+	"net/http"
+	"net/http/httptest"
 	"os"
 	"testing"
 
@@ -49,3 +51,134 @@ func TestHerokuDriver(t *testing.T) {
 	assert.True(t, r.IsAdmin)
 	require.NotNil(t, r.CreatedAt)
 }
+
+// TestHerokuDriverPersonalAccount exercises personal mode (empty teamID): a
+// solo account with no Team is reviewed via its apps' owner + collaborators.
+// It verifies the owner is always included, collaborators are deduped across
+// apps, and team-owned apps are skipped.
+func TestHerokuDriverPersonalAccount(t *testing.T) {
+	t.Parallel()
+
+	srv := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		assert.Equal(t, http.MethodGet, r.Method)
+		w.Header().Set("Content-Type", "application/json")
+
+		switch r.URL.Path {
+		case "/apps":
+			w.WriteHeader(http.StatusOK)
+			_, _ = w.Write([]byte(`[
+				{"id":"app-1","name":"one","owner":{"id":"u-alice","email":"alice@example.com"},"team":null},
+				{"id":"app-2","name":"two","owner":{"id":"u-alice","email":"alice@example.com"},"team":null},
+				{"id":"app-3","name":"teamed","owner":{"id":"u-x","email":"x@example.com"},"team":{"id":"team-1"}}
+			]`))
+		case "/apps/app-1/collaborators":
+			w.WriteHeader(http.StatusOK)
+			_, _ = w.Write([]byte(`[
+				{"id":"c-1","role":"owner","user":{"id":"u-alice","email":"alice@example.com"}},
+				{"id":"c-2","role":"member","user":{"id":"u-bob","email":"bob@example.com"}}
+			]`))
+		case "/apps/app-2/collaborators":
+			w.WriteHeader(http.StatusOK)
+			_, _ = w.Write([]byte(`[
+				{"id":"c-3","role":"member","user":{"id":"u-bob","email":"bob@example.com"}},
+				{"id":"c-4","role":"member","user":{"id":"u-carol","email":"carol@example.com"}}
+			]`))
+		default:
+			t.Errorf("unexpected request to %s", r.URL.Path)
+			w.WriteHeader(http.StatusNotFound)
+		}
+	}))
+	defer srv.Close()
+
+	client := &http.Client{Transport: &hostRewriter{target: srv.URL}}
+
+	records, err := NewHerokuDriver(client, "").ListAccounts(context.Background())
+	require.NoError(t, err)
+
+	byEmail := make(map[string]AccountRecord, len(records))
+	for _, r := range records {
+		byEmail[r.Email] = r
+	}
+
+	require.Len(t, records, 3)
+	assert.Contains(t, byEmail, "alice@example.com")
+	assert.Contains(t, byEmail, "bob@example.com")
+	assert.Contains(t, byEmail, "carol@example.com")
+
+	assert.True(t, byEmail["alice@example.com"].IsAdmin)
+	assert.Equal(t, "owner", byEmail["alice@example.com"].Role)
+	assert.False(t, byEmail["bob@example.com"].IsAdmin)
+}
+
+// TestHerokuDriverPersonalAccountSlug verifies the reserved personal-account
+// slug routes to personal mode just like an empty teamID.
+func TestHerokuDriverPersonalAccountSlug(t *testing.T) {
+	t.Parallel()
+
+	srv := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		w.Header().Set("Content-Type", "application/json")
+
+		switch r.URL.Path {
+		case "/apps":
+			w.WriteHeader(http.StatusOK)
+			_, _ = w.Write([]byte(`[{"id":"app-1","name":"one","owner":{"id":"u-alice","email":"alice@example.com"},"team":null}]`))
+		case "/apps/app-1/collaborators":
+			w.WriteHeader(http.StatusOK)
+			_, _ = w.Write([]byte(`[]`))
+		default:
+			t.Errorf("unexpected request to %s", r.URL.Path)
+			w.WriteHeader(http.StatusNotFound)
+		}
+	}))
+	defer srv.Close()
+
+	client := &http.Client{Transport: &hostRewriter{target: srv.URL}}
+
+	records, err := NewHerokuDriver(client, herokuPersonalAccountSlug).ListAccounts(context.Background())
+	require.NoError(t, err)
+	require.Len(t, records, 1)
+	assert.Equal(t, "alice@example.com", records[0].Email)
+}
+
+// TestHerokuDriverPersonalAccountErrors verifies non-2xx responses on the
+// personal-mode endpoints propagate as errors rather than empty results.
+func TestHerokuDriverPersonalAccountErrors(t *testing.T) {
+	t.Parallel()
+
+	cases := []struct {
+		name      string
+		appsCode  int
+		collabFor string
+	}{
+		{name: "apps list fails", appsCode: http.StatusInternalServerError},
+		{name: "collaborators fail", appsCode: http.StatusOK, collabFor: "app-1"},
+	}
+
+	for _, tc := range cases {
+		t.Run(tc.name, func(t *testing.T) {
+			t.Parallel()
+
+			srv := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+				w.Header().Set("Content-Type", "application/json")
+
+				switch r.URL.Path {
+				case "/apps":
+					w.WriteHeader(tc.appsCode)
+					_, _ = w.Write([]byte(`[{"id":"app-1","name":"one","owner":{"id":"u-alice","email":"alice@example.com"},"team":null}]`))
+				case "/apps/app-1/collaborators":
+					w.WriteHeader(http.StatusForbidden)
+					_, _ = w.Write([]byte(`{"id":"forbidden"}`))
+				default:
+					t.Errorf("unexpected request to %s", r.URL.Path)
+					w.WriteHeader(http.StatusNotFound)
+				}
+			}))
+			defer srv.Close()
+
+			client := &http.Client{Transport: &hostRewriter{target: srv.URL}}
+
+			_, err := NewHerokuDriver(client, "").ListAccounts(context.Background())
+			require.Error(t, err)
+		})
+	}
+}