[feature] Implement the preferences client API (#1740)

This adds the preferences endpoint to our Mastodon Client API
implementation. It's a read-only endpoint that returns a number of
user preferences. Applications can query these settings when logging in
a user (for the first time) to configure themselves.

internal/processing/preferences_test.go

@@ -0,0 +1,74 @@
+// GoToSocial
+// Copyright (C) GoToSocial Authors admin@gotosocial.org
+// SPDX-License-Identifier: AGPL-3.0-or-later
+//
+// This program is free software: you can redistribute it and/or modify
+// it under the terms of the GNU Affero General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+//
+// This program is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU Affero General Public License for more details.
+//
+// You should have received a copy of the GNU Affero General Public License
+// along with this program.  If not, see <http://www.gnu.org/licenses/>.
+
+package processing_test
+
+import (
+	"context"
+	"testing"
+
+	"github.com/stretchr/testify/suite"
+	"github.com/superseriousbusiness/gotosocial/internal/api/model"
+	"github.com/superseriousbusiness/gotosocial/internal/gtsmodel"
+)
+
+type PreferencesTestSuite struct {
+	ProcessingStandardTestSuite
+}
+
+func (suite *PreferencesTestSuite) TestPreferencesGet() {
+	ctx := context.Background()
+	tests := []struct {
+		act   *gtsmodel.Account
+		prefs *model.Preferences
+	}{
+		{
+			act: suite.testAccounts["local_account_1"],
+			prefs: &model.Preferences{
+				PostingDefaultVisibility: "public",
+				PostingDefaultSensitive:  false,
+				PostingDefaultLanguage:   "en",
+				ReadingExpandMedia:       "default",
+				ReadingExpandSpoilers:    false,
+				ReadingAutoPlayGifs:      false,
+			},
+		},
+		{
+			act: suite.testAccounts["local_account_2"],
+			prefs: &model.Preferences{
+				PostingDefaultVisibility: "private",
+				PostingDefaultSensitive:  true,
+				PostingDefaultLanguage:   "fr",
+				ReadingExpandMedia:       "default",
+				ReadingExpandSpoilers:    false,
+				ReadingAutoPlayGifs:      false,
+			},
+		},
+	}
+
+	for _, tt := range tests {
+		suite.Run(tt.act.ID, func() {
+			prefs, err := suite.processor.PreferencesGet(ctx, tt.act.ID)
+			suite.NoError(err)
+			suite.Equal(tt.prefs, prefs)
+		})
+	}
+}
+
+func TestPreferencesTestSuite(t *testing.T) {
+	suite.Run(t, &PreferencesTestSuite{})
+}