Add consolidateLists function with unit tests

libloki/service_nodes.js

@@ -0,0 +1,29 @@
+function consolidateLists(lists, threshold = 1){
+  if (typeof threshold !== 'number') {
+    throw Error('Provided threshold is not a number');
+  }
+
+  // calculate list size manually since `Set`
+  // does not have a `length` attribute
+  let listSize = 0;
+  const occurences = {};
+  lists.forEach(list => {
+    listSize += 1;
+    list.forEach(item => {
+      if (!(item in occurences)) {
+        occurences[item] = 1;
+      } else {
+        occurences[item] += 1;
+      }
+    });
+  });
+
+  const scaledThreshold = listSize * threshold;
+  return Object.entries(occurences)
+    .filter(keyValue => keyValue[1] >= scaledThreshold)
+    .map(keyValue => keyValue[0]);
+}
+
+module.exports = {
+  consolidateLists,
+}

libloki/test/node/.eslintrc.js

@@ -0,0 +1,22 @@
+// For reference: https://github.com/airbnb/javascript
+
+module.exports = {
+  env: {
+    mocha: true,
+    browser: false,
+  },
+
+  parserOptions: {
+    sourceType: 'module',
+  },
+
+  rules: {
+    // We still get the value of this rule, it just allows for dev deps
+    'import/no-extraneous-dependencies': [
+      'error',
+      {
+        devDependencies: true,
+      },
+    ],
+  },
+};

libloki/test/node/service_nodes_test.js

@@ -0,0 +1,58 @@
+const ServiceNode = require('../../service_nodes');
+const { expect } = require('chai');
+
+describe('ServiceNodes', () => {
+  describe('#consolidateLists', () => {
+    it('should throw when provided a non-iterable list', () => {
+      expect(() => ServiceNode.consolidateLists(null, 1)).to.throw();
+    });
+    it('should throw when provided a non-iterable item in the list', () => {
+      expect(() => ServiceNode.consolidateLists([1, 2, 3], 1)).to.throw();
+    });
+    it('should throw when provided a non-number threshold', () => {
+      expect(() => ServiceNode.consolidateLists([], 'a')).to.throw();
+    });
+    it('should return an empty array when the input is an empty array', () => {
+      const result = ServiceNode.consolidateLists([]);
+      expect(result).to.deep.equal([]);
+    });
+    it('should return the input when only 1 list is provided', () => {
+      const result = ServiceNode.consolidateLists([['a', 'b', 'c']]);
+      expect(result).to.deep.equal(['a', 'b', 'c']);
+    });
+    it('should return the union of all lists when threshold is 0', () => {
+      const result = ServiceNode.consolidateLists([
+        ['a', 'b', 'c', 'h'],
+        ['d', 'e', 'f', 'g'],
+        ['g', 'h'],
+      ], 0);
+      expect(result.sort()).to.deep.equal(['a', 'b', 'c', 'd', 'e', 'f', 'g', 'h']);
+    });
+    it('should return the intersection of all lists when threshold is 1', () => {
+      const result = ServiceNode.consolidateLists([
+        ['a', 'b', 'c', 'd'],
+        ['a', 'e', 'f', 'g'],
+        ['a', 'h'],
+      ], 1);
+      expect(result).to.deep.equal(['a']);
+    });
+    it('should return the elements that have an occurence >= the provided threshold', () => {
+      const result = ServiceNode.consolidateLists([
+        ['a', 'b', 'c', 'd', 'e', 'f', 'g'],
+        ['a', 'b', 'c', 'd', 'e', 'f', 'h'],
+        ['a', 'b', 'c', 'd', 'e', 'f', 'g'],
+        ['a', 'b', 'c', 'd', 'e', 'g', 'h'],
+      ], 3/4);
+      expect(result).to.deep.equal(['a', 'b', 'c', 'd', 'e', 'f', 'g']);
+    });
+    it('should work with sets as well', () => {
+      const result = ServiceNode.consolidateLists(new Set([
+        new Set(['a', 'b', 'c', 'd', 'e', 'f', 'g']),
+        new Set(['a', 'b', 'c', 'd', 'e', 'f', 'h']),
+        new Set(['a', 'b', 'c', 'd', 'e', 'f', 'g']),
+        new Set(['a', 'b', 'c', 'd', 'e', 'g', 'h']),
+      ]), 3/4);
+      expect(result).to.deep.equal(['a', 'b', 'c', 'd', 'e', 'f', 'g']);
+    });
+  });
+});

package.json

@@ -31,7 +31,7 @@
     "test-lib-view": "NODE_ENV=test-lib yarn run start",
     "test-loki-view": "NODE_ENV=test-loki yarn run start",
     "test-electron": "yarn grunt test",
-    "test-node": "mocha --recursive test/app test/modules ts/test",
+    "test-node": "mocha --recursive test/app test/modules ts/test libloki/test/node",
     "test-node-coverage": "nyc --reporter=lcov --reporter=text mocha --recursive test/app test/modules ts/test",
     "eslint": "eslint .",
     "lint": "yarn format --list-different && yarn lint-windows",