History: Add HistoryEntry

With this the backend now can hold a history entry.
Also included in this commit are some minor changes to tests and services so they can still work.

Signed-off-by: Philip Molares <philip.molares@udo.edu>

src/history/history-entry.entity.ts

@@ -0,0 +1,47 @@
+/*
+ * SPDX-FileCopyrightText: 2021 The HedgeDoc developers (see AUTHORS file)
+ *
+ * SPDX-License-Identifier: AGPL-3.0-only
+ */
+
+import {
+  Column,
+  Entity,
+  ManyToOne,
+  UpdateDateColumn,
+} from 'typeorm';
+import { User } from '../users/user.entity';
+import { Note } from '../notes/note.entity';
+
+@Entity()
+export class HistoryEntry {
+  @ManyToOne((_) => User, (user) => user.historyEntries, {
+    onDelete: 'CASCADE',
+    primary: true,
+  })
+  user: User;
+
+  @ManyToOne((_) => Note, (note) => note.historyEntries, {
+    onDelete: 'CASCADE',
+    primary: true,
+  })
+  note: Note;
+
+  @Column()
+  pinStatus: boolean;
+
+  @UpdateDateColumn()
+  updatedAt: Date;
+
+  // The optional note parameter is necessary for the createNote method in the NotesService,
+  // as we create the note then and don't need to add it to the HistoryEntry.
+  public static create(user: User, note?: Note): HistoryEntry {
+    const newHistoryEntry = new HistoryEntry();
+    newHistoryEntry.user = user;
+    if (note) {
+      newHistoryEntry.note = note;
+    }
+    newHistoryEntry.pinStatus = false;
+    return newHistoryEntry;
+  }
+}