Fix incorrect behaviour when filtering by assignee in issues with multiple assignees (#415)

Hide assignees not selected in filter

For issues with multiple assignees, having one of the assignees selected
in the filter displays all other assignees as groups.

This is misleading behaviour since the assignees that are not selected
are expected to be hidden.

Let's add a check for if the group is selected in the filter before
displaying the data.

Author: IzN432

src/app/core/models/github-user.model.ts

@@ -52,6 +52,27 @@ export class GithubUser implements RawGithubUser, Group {
     Object.assign(this, rawData);
   }
 
+  /*
+  This method is used to enable comparisons between
+  a Group and the filtering criteria, which is stored
+  as a string, in IssuesDataTable.ts
+  */
+  static fromUsername(username: string) {
+    return new GithubUser({
+      login: username,
+      avatar_url: '',
+      created_at: '',
+      html_url: '',
+      name: '',
+      node_id: '',
+      two_factor_authentication: false,
+      site_admin: false,
+      type: '',
+      updated_at: '',
+      url: ''
+    });
+  }
+
   equals(other: any) {
     if (!(other instanceof GithubUser)) {
       return false;

src/app/core/models/milestone.model.ts

@@ -18,6 +18,15 @@ export class Milestone implements Group {
     this.number = milestone.number ? +milestone.number : undefined;
   }
 
+  /*
+  This method is used to enable comparisons between
+  a Group and the filtering criteria, which is stored
+  as a string, in IssuesDataTable.ts
+  */
+  static fromTitle(title: string): Milestone {
+    return new Milestone({ title, state: '' });
+  }
+
   public equals(other: any) {
     if (!(other instanceof Milestone)) {
       return false;

src/app/shared/issue-tables/IssuesDataTable.ts

@@ -2,8 +2,10 @@ import { DataSource } from '@angular/cdk/table';
 import { MatPaginator } from '@angular/material/paginator';
 import { BehaviorSubject, merge, Observable, Subscription } from 'rxjs';
 import { map } from 'rxjs/operators';
+import { GithubUser } from '../../core/models/github-user.model';
 import { Group } from '../../core/models/github/group.interface';
 import { Issue } from '../../core/models/issue.model';
+import { Milestone } from '../../core/models/milestone.model';
 import { AssigneeService } from '../../core/services/assignee.service';
 import { Filter, FiltersService } from '../../core/services/filters.service';
 import { GroupingContextService } from '../../core/services/grouping/grouping-context.service';
@@ -23,6 +25,21 @@ export class IssuesDataTable extends DataSource<Issue> implements FilterableSour
 
   public isLoading$ = this.issueService.isLoading.asObservable();
 
+  private static isGroupInFilter(group: Group, filter: Filter): boolean {
+    const groupFilterAsGithubUser = filter.assignees.map((selectedAssignee) => {
+      return GithubUser.fromUsername(selectedAssignee);
+    });
+    const groupFilterAsMilestone = filter.milestones.map((selectedMilestone) => {
+      return Milestone.fromTitle(selectedMilestone);
+    });
+
+    const isGroupInFilter =
+      groupFilterAsGithubUser.some((githubUser) => group?.equals(githubUser)) ||
+      groupFilterAsMilestone.some((milestone) => group?.equals(milestone));
+
+    return isGroupInFilter;
+  }
+
   constructor(
     private issueService: IssueService,
     private groupingContextService: GroupingContextService,
@@ -63,6 +80,11 @@ export class IssuesDataTable extends DataSource<Issue> implements FilterableSour
       .pipe(
         // maps each change in display value to new issue ordering or filtering
         map(() => {
+          if (!IssuesDataTable.isGroupInFilter(this.group, this.filter)) {
+            this.count = 0;
+            return [];
+          }
+
           let data = <Issue[]>Object.values(this.issueService.issues$.getValue()).reverse();
           if (this.defaultFilter) {
             data = data.filter(this.defaultFilter);