feat: add membership calcuation tests

Author: brage-andreas

apps/rpc/src/modules/user/membership-service.ts

@@ -3,14 +3,34 @@ import { differenceInMonths, subYears } from "date-fns"
 import invariant from "tiny-invariant"
 import type { NTNUGroup } from "../feide/feide-groups-repository"
 import { getLogger } from "@dotkomonline/logger"
-import { getCurrentUTC } from "@dotkomonline/utils"
-import type { TZDate } from "@date-fns/tz"
 
 export interface MembershipService {
-  findEstimatedStudyStart(
+  /**
+   * Find the approximate semester based on a student's courses against a hard-coded set of courses.
+   * 
+   * NOTE: The value is 0-indexed.
+   * 
+   * Master studies begin at semester 6.
+   * 
+   * @see getCourseStart(semester) in types package
+   * @see getStudyGrade(semester) in types package
+   * 
+   * @example
+   * findEstimatedSemester(...) -> 0 // 1st semester Bachelor (Autumn)
+   * findEstimatedSemester(...) -> 1 // 2nd semester Bachelor (Spring)
+   * findEstimatedSemester(...) -> 2 // 3rd semester Bachelor
+   * findEstimatedSemester(...) -> 3 // 4th semester Bachelor
+   * findEstimatedSemester(...) -> 4 // 5th semester Bachelor
+   * findEstimatedSemester(...) -> 5 // 6th semester Bachelor
+   * findEstimatedSemester(...) -> 6 // 1st semester Master (regardless of prior Bachelor length)
+   * findEstimatedSemester(...) -> 7 // 2nd semester Master
+   * findEstimatedSemester(...) -> 8 // 3rd semester Master
+   * findEstimatedSemester(...) -> 9 // 4th semester Master
+   */
+  findEstimatedSemester(
     study: "BACHELOR" | "MASTER",
-    courses: NTNUGroup[]
-  ): { start: TZDate; semester: number; grade: number }
+    courses: ReadonlyArray<NTNUGroup>
+  ): number
 }
 
 const BACHELOR_STUDY_PLAN = [
@@ -44,19 +64,19 @@ const BACHELOR_STUDY_PLAN = [
 
 const MASTER_STUDY_PLAN = [
   {
-    semester: 0,
+    semester: 6,
     courses: [],
   },
   {
-    semester: 1,
+    semester: 7,
     courses: [],
   },
   {
-    semester: 2,
+    semester: 8,
     courses: ["IT3915"],
   },
   {
-    semester: 3,
+    semester: 9,
     courses: ["IT3920"],
   },
 ] as const
@@ -90,8 +110,7 @@ export function getMembershipService(): MembershipService {
   /**
    * Find the approximate semester based on a student's courses against a hard-coded set of courses.
    */
-  function findEstimatedSemester(courseSet: StudyPlanCourseSet, studentCourses: NTNUGroup[]): number {
-    logger.info("Searching for applicable membership based on courses %o and study plan %o", studentCourses, courseSet)
+  function estimateSemester(courseSet: StudyPlanCourseSet, studentCourses: ReadonlyArray<NTNUGroup>): number {
     let largestSemester = 0
     for (let i = 0; i < courseSet.length; i++) {
       const semester = courseSet[i]
@@ -176,33 +195,9 @@ export function getMembershipService(): MembershipService {
   }
 
   return {
-    findEstimatedStudyStart(study, courses) {
+    findEstimatedSemester(study, courses) {
       const studyPlan = study === "MASTER" ? MASTER_STUDY_PLAN : BACHELOR_STUDY_PLAN
-      const semester = findEstimatedSemester(studyPlan, courses)
-
-      // We use Math#round because it will give us the correct year delta:
-      //   Year 1 autumn (value 0)  : round(0 / 2) = 0 (Start year = current year)
-      //   Year 1 spring (value 1): round(1 / 2) = 1 (Start year = current - 1, since spring is in the next calendar year)
-      //   Year 2 autumn (value 2)  : round(2 / 2) = 1 (Start year = current - 1)
-      //   Year 2 spring (value 3): round(3 / 2) = 2 (Start year = current - 2)
-      //   ...
-      const yearOffset = Math.round(semester / 2)
-      const start = subYears(getAcademicStart(getCurrentUTC()), yearOffset)
-
-      // A school year consists of two semesters (Autumn and Spring). So this formula will give us the year:
-      //   Year 1 autumn (value 0): floor(0 / 2) + 1 = 1 (Year 1)
-      //   Year 1 spring (value 1): floor(1 / 2) + 1 = 1 (Year 1)
-      //   Year 2 autumn (value 2): floor(2 / 2) + 1 = 2 (Year 2)
-      //   Year 2 spring (value 3): floor(3 / 2) + 1 = 2 (Year 2)
-      //   Year 3 autumn (value 4): floor(4 / 2) + 1 = 3 (Year 3)
-      //   ...
-      const grade = Math.floor(semester / 2) + 1
-
-      return {
-        semester,
-        start,
-        grade,
-      }
+      return estimateSemester(studyPlan, courses)
     },
   }
 }