Improved average calculation

Author: stasel

server/src/controllers/CohortsController.ts

@@ -1,6 +1,6 @@
 import { Request, Response } from 'express';
 import { TraineesRepository } from '../repositories';
-import { LearningStatus, Test, Trainee } from '../models';
+import { LearningStatus, calculateAverageTestScore, Trainee } from '../models';
 
 interface Cohort {
   cohort: number | null;
@@ -76,24 +76,10 @@ export class CohortsController implements CohortsControllerType {
       LearningStatus: trainee.educationInfo.learningStatus,
       JobPath: trainee.employmentInfo.jobPath,
       strikes: trainee.educationInfo.strikes.length,
-      averageTestScore: this.calculateAverageTestScore(trainee.educationInfo.tests),
+      averageTestScore: calculateAverageTestScore(trainee.educationInfo.tests),
     };
   }
 
-  private calculateAverageTestScore(tests: Test[]): number | null {
-    // Filter out tests without scores
-    const scores = tests.map((test) => test.score).filter((score) => score !== undefined);
-    if (scores.length === 0) {
-      return null;
-    }
-
-    // Calculate average
-    const sum = scores.reduce((acc, score) => {
-      return acc + score;
-    }, 0);
-    return sum / scores.length;
-  }
-
   private compareTraineeInCohort(a: Trainee, b: Trainee) {
     const statusIndexA = Object.values(LearningStatus).indexOf(a.educationInfo.learningStatus);
     const statusIndexB = Object.values(LearningStatus).indexOf(b.educationInfo.learningStatus);

server/src/models/Test.ts

@@ -4,7 +4,7 @@ export interface Test {
   readonly id: string;
   date: Date;
   type: TestType;
-  score?: number;
+  score: number | null;
   result: TestResult;
   comments?: string;
 }
@@ -20,3 +20,36 @@ export const validateTest = (test: Test): void => {
     throw new Error(`Unknown test type [${Object.values(TestType)}]`);
   }
 };
+
+// Calculate average of all test scores, taking only the highest score for each test type
+export const calculateAverageTestScore = (tests: Test[]): number | null => {
+  // Group by test type
+  const testTypes = Object.groupBy(tests, (test) => test.type);
+
+  // Select highest test for each type
+  const scores = Object.values(testTypes)
+    .map((testsWithTheSameType) => {
+      return getTestWithMaxScore(testsWithTheSameType);
+    })
+    .map((test) => test?.score)
+    .filter((score) => score !== null && score !== undefined);
+
+  // Filter out tests without scores
+  if (scores.length === 0) {
+    return null;
+  }
+
+  // Calculate average
+  const sum = scores.reduce((acc, score) => {
+    return acc + score;
+  }, 0);
+  return sum / scores.length;
+};
+
+// Helper function to get the best test (highest score) from a list of tests
+const getTestWithMaxScore = (tests: Test[]): Test | null => {
+  const sortedByScore = tests
+    .filter((test: Test) => test.score !== null)
+    .sort((a, b) => (b.score ?? 0) - (a.score ?? 0));
+  return sortedByScore[0] ?? null;
+};

server/src/repositories/TraineesRepository.ts

@@ -71,6 +71,7 @@ export class MongooseTraineesRepository implements TraineesRepository {
         'educationInfo.learningStatus',
         'educationInfo.strikes.id',
         'educationInfo.tests.score',
+        'educationInfo.tests.type',
         'educationInfo.currentCohort',
         'employmentInfo.jobPath',
       ])