Pick servers for ?via on matrix.to links based on some heuristics

test/matrix-to-test.js

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+/*
+Copyright 2018 New Vector Ltd
+Licensed under the Apache License, Version 2.0 (the "License");
+you may not use this file except in compliance with the License.
+You may obtain a copy of the License at
+    http://www.apache.org/licenses/LICENSE-2.0
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License.
+*/
+
+import expect from 'expect';
+import peg from '../src/MatrixClientPeg';
+import {pickServerCandidates} from "../src/matrix-to";
+
+
+describe('matrix-to', function () {
+    it('should pick no candidate servers when the room is not found', function () {
+        //peg.getRoom = () => null;
+        const pickedServers = pickServerCandidates("!somewhere:example.org");
+        expect(pickedServers).toExist();
+        expect(pickedServers.length).toBe(0);
+    });
+    it('should pick no candidate servers when the room has no members', function () {
+        peg.getRoom = () => {
+            return {
+                getJoinedMembers: () => [],
+            }
+        };
+        const pickedServers = pickServerCandidates("!somewhere:example.org");
+        expect(pickedServers).toExist();
+        expect(pickedServers.length).toBe(0);
+    });
+    it('should pick no candidate servers when no users have enough power level', function () {
+        peg.getRoom = () => {
+            return {
+                getJoinedMembers: () => [
+                    {
+                        userId: "@alice:example.org",
+                        powerLevel: 0,
+                    },
+                    {
+                        userId: "@bob:example.org",
+                        powerLevel: 25,
+                    }
+                ],
+            }
+        };
+        const pickedServers = pickServerCandidates("!somewhere:example.org");
+        expect(pickedServers).toExist();
+        expect(pickedServers.length).toBe(0);
+    });
+    it('should pick a candidate server for the highest power level user in the room', function () {
+        peg.getRoom = () => {
+            return {
+                getJoinedMembers: () => [
+                    {
+                        userId: "@alice:pl_50",
+                        powerLevel: 50,
+                    },
+                    {
+                        userId: "@alice:pl_75",
+                        powerLevel: 75,
+                    },
+                    {
+                        userId: "@alice:pl_95",
+                        powerLevel: 95,
+                    }
+                ],
+            }
+        };
+        const pickedServers = pickServerCandidates("!somewhere:example.org");
+        expect(pickedServers).toExist();
+        expect(pickedServers.length).toBe(3);
+        expect(pickedServers[0]).toBe("pl_95");
+        // we don't check the 2nd and 3rd servers because that is done by the next test
+    });
+    it('should pick candidate servers based on user population', function () {
+        peg.getRoom = () => {
+            return {
+                getJoinedMembers: () => [
+                    {
+                        userId: "@alice:first",
+                        powerLevel: 0,
+                    },
+                    {
+                        userId: "@bob:first",
+                        powerLevel: 0,
+                    },
+                    {
+                        userId: "@charlie:first",
+                        powerLevel: 0,
+                    },
+                    {
+                        userId: "@alice:second",
+                        powerLevel: 0,
+                    },
+                    {
+                        userId: "@bob:second",
+                        powerLevel: 0,
+                    },
+                    {
+                        userId: "@charlie:third",
+                        powerLevel: 0,
+                    }
+                ],
+            }
+        };
+        const pickedServers = pickServerCandidates("!somewhere:example.org");
+        expect(pickedServers).toExist();
+        expect(pickedServers.length).toBe(3);
+        expect(pickedServers[0]).toBe("first");
+        expect(pickedServers[1]).toBe("second");
+        expect(pickedServers[2]).toBe("third");
+    });
+    it('should pick prefer candidate servers with higher power levels', function () {
+        peg.getRoom = () => {
+            return {
+                getJoinedMembers: () => [
+                    {
+                        userId: "@alice:first",
+                        powerLevel: 100,
+                    },
+                    {
+                        userId: "@alice:second",
+                        powerLevel: 0,
+                    },
+                    {
+                        userId: "@bob:second",
+                        powerLevel: 0,
+                    },
+                    {
+                        userId: "@charlie:third",
+                        powerLevel: 0,
+                    }
+                ],
+            }
+        };
+        const pickedServers = pickServerCandidates("!somewhere:example.org");
+        expect(pickedServers).toExist();
+        expect(pickedServers.length).toBe(3);
+        expect(pickedServers[0]).toBe("first");
+        expect(pickedServers[1]).toBe("second");
+        expect(pickedServers[2]).toBe("third");
+    });
+});