feat: add RCV Copeland voting system

package.json

@@ -1,6 +1,6 @@
 {
   "name": "@snapshot-labs/snapshot.js",
-  "version": "0.12.50",
+  "version": "0.12.51",
   "repository": "snapshot-labs/snapshot.js",
   "license": "MIT",
   "main": "dist/snapshot.cjs.js",

src/schemas/proposal.json

@@ -47,6 +47,7 @@
             "approval",
             "ranked-choice",
             "quadratic",
+            "copeland",
             "weighted",
             "custom",
             "basic"

src/voting/__snapshots__/copeland.spec.js.snap

@@ -0,0 +1,134 @@
+// Vitest Snapshot v1, https://vitest.dev/guide/snapshot.html
+
+exports[`Partial ranking 1`] = `
+[
+  4,
+  6,
+  2,
+  0,
+]
+`;
+
+exports[`getScores 1`] = `
+[
+  5,
+  5,
+  2,
+  0,
+]
+`;
+
+exports[`getScores 2`] = `
+[
+  5,
+  5,
+  2,
+  0,
+]
+`;
+
+exports[`getScores 3`] = `
+[
+  5,
+  5,
+  2,
+  0,
+]
+`;
+
+exports[`getScores 4`] = `
+[
+  5,
+  5,
+  2,
+  0,
+]
+`;
+
+exports[`getScoresByStrategy 1`] = `
+[
+  [
+    5,
+  ],
+  [
+    5,
+  ],
+  [
+    2,
+  ],
+  [
+    0,
+  ],
+]
+`;
+
+exports[`getScoresByStrategy 2`] = `
+[
+  [
+    5,
+  ],
+  [
+    5,
+  ],
+  [
+    2,
+  ],
+  [
+    0,
+  ],
+]
+`;
+
+exports[`getScoresByStrategy 3`] = `
+[
+  [
+    5,
+    5,
+    5,
+  ],
+  [
+    5,
+    5,
+    5,
+  ],
+  [
+    2,
+    2,
+    2,
+  ],
+  [
+    0,
+    0,
+    0,
+  ],
+]
+`;
+
+exports[`getScoresByStrategy 4`] = `
+[
+  [
+    5,
+    5,
+    5,
+  ],
+  [
+    5,
+    5,
+    5,
+  ],
+  [
+    2,
+    2,
+    2,
+  ],
+  [
+    0,
+    0,
+    0,
+  ],
+]
+`;
+
+exports[`getScoresTotal 1`] = `4`;
+
+exports[`getScoresTotal 2`] = `12`;

src/voting/copeland.spec.js

@@ -0,0 +1,129 @@
+import { test, expect } from 'vitest';
+import CopelandVoting from './copeland';
+import example from './examples/copeland.json';
+
+// Helper function to create a more complex example with multiple strategies
+const example2 = () => {
+  const proposal = {
+    choices: ['Alice', 'Bob', 'Carol', 'David']
+  };
+  const strategies = [
+    { name: 'ticket', network: '1', params: {} },
+    { name: 'ticket', network: '1', params: {} },
+    { name: 'ticket', network: '1', params: {} }
+  ];
+  const votes = example.votes.map((vote) => ({
+    choice: vote.choice,
+    balance: 3,
+    scores: [1, 1, 1]
+  }));
+
+  return {
+    proposal,
+    strategies,
+    votes
+  };
+};
+
+// Generate a set of votes including some invalid choices
+const votesWithInvalidChoices = () => {
+  const invalidVotes = [
+    { choice: [0, 1], balance: 1, scores: [1] },
+    { choice: [1, 5], balance: 1, scores: [1] },
+    { choice: [1, 1], balance: 1, scores: [1] },
+    { choice: [], balance: 1, scores: [1] },
+    { choice: [1, 2, 3, 4, 5], balance: 1, scores: [1] }
+  ];
+  return [...invalidVotes, ...example.votes];
+};
+
+// Generate a set of votes including some invalid choices for the multi-strategy example
+const votesWithInvalidChoices2 = () => {
+  const invalidVotes = [
+    { choice: [0, 1], balance: 3, scores: [1, 1, 1] },
+    { choice: [1, 5], balance: 3, scores: [1, 1, 1] },
+    { choice: [1, 1], balance: 3, scores: [1, 1, 1] },
+    { choice: [], balance: 3, scores: [1, 1, 1] },
+    { choice: [1, 2, 3, 4, 5], balance: 3, scores: [1, 1, 1] }
+  ];
+  return [...invalidVotes, ...example2().votes];
+};
+
+// Test cases for getScores method
+test.each([
+  [example.proposal, example.votes, example.strategies],
+  [example.proposal, votesWithInvalidChoices(), example.strategies],
+  [example2().proposal, example2().votes, example2().strategies],
+  [example2().proposal, votesWithInvalidChoices2(), example2().strategies]
+])('getScores', (proposal, votes, strategies) => {
+  const copeland = new CopelandVoting(
+    proposal,
+    votes,
+    strategies,
+    example.selectedChoice
+  );
+  expect(copeland.getScores()).toMatchSnapshot();
+});
+
+// Test cases for getScoresByStrategy method
+test.each([
+  [example.proposal, example.votes, example.strategies],
+  [example.proposal, votesWithInvalidChoices(), example.strategies],
+  [example2().proposal, example2().votes, example2().strategies],
+  [example2().proposal, votesWithInvalidChoices2(), example2().strategies]
+])('getScoresByStrategy', (proposal, votes, strategies) => {
+  const copeland = new CopelandVoting(
+    proposal,
+    votes,
+    strategies,
+    example.selectedChoice
+  );
+  expect(copeland.getScoresByStrategy()).toMatchSnapshot();
+});
+
+// Test cases for getScoresTotal method
+test.each([
+  [example.proposal, example.votes, example.strategies],
+  [example2().proposal, example2().votes, example2().strategies]
+])('getScoresTotal', (proposal, votes, strategies) => {
+  const copeland = new CopelandVoting(
+    proposal,
+    votes,
+    strategies,
+    example.selectedChoice
+  );
+  expect(copeland.getScoresTotal()).toMatchSnapshot();
+});
+
+// Test cases for getChoiceString method
+test.each([
+  [[1, 2], 'Alice, Bob'],
+  [[4, 2, 3, 1], 'David, Bob, Carol, Alice']
+])('getChoiceString %s', (selected, expected) => {
+  const copeland = new CopelandVoting(
+    example.proposal,
+    example.votes,
+    example.strategies,
+    selected
+  );
+  expect(copeland.getChoiceString()).toBe(expected);
+});
+
+// Test case for partial ranking
+test('Partial ranking', () => {
+  const partialVotes = [
+    ...example.votes,
+    {
+      choice: [2, 1],
+      balance: 1,
+      scores: [1]
+    }
+  ];
+  const copeland = new CopelandVoting(
+    example.proposal,
+    partialVotes,
+    example.strategies,
+    example.selectedChoice
+  );
+  expect(copeland.getScores()).toMatchSnapshot();
+});