Database: Generates unique reproducible md5 hash

jest.config.ts

@@ -1,5 +1,6 @@
 export default {
   preset: 'ts-jest',
+  testTimeout: 60000,
   moduleNameMapper: {
     '^@mswjs/data(.*)': '<rootDir>/$1',
   },

package.json

@@ -37,10 +37,12 @@
     "typescript": "^4.2.4"
   },
   "dependencies": {
+    "@types/md5": "^2.3.0",
     "@types/pluralize": "^0.0.29",
     "@types/uuid": "^8.3.0",
     "date-fns": "^2.20.0",
     "graphql": "^15.5.0",
+    "md5": "^2.3.0",
     "pluralize": "^8.0.0",
     "strict-event-emitter": "^0.2.0",
     "uuid": "^8.3.1"

src/db/Database.ts

@@ -1,3 +1,4 @@
+import md5 from 'md5'
 import { StrictEventEmitter } from 'strict-event-emitter'
 import { EntityInstance, ModelDictionary, PrimaryKeyType } from '../glossary'
 
@@ -7,6 +8,7 @@ type Models<Dictionary extends ModelDictionary> = Record<
 >
 
 export type DatabaseMethodToEventFn<Method extends (...args: any[]) => any> = (
+  id: string,
   ...args: Parameters<Method>
 ) => void
 
@@ -16,7 +18,10 @@ export interface DatabaseEventsMap {
   delete: DatabaseMethodToEventFn<Database<any>['delete']>
 }
 
+let callOrder = 0
+
 export class Database<Dictionary extends ModelDictionary> {
+  public id: string
   public events: StrictEventEmitter<DatabaseEventsMap>
   private models: Models<ModelDictionary>
 
@@ -29,6 +34,21 @@ export class Database<Dictionary extends ModelDictionary> {
       },
       {},
     )
+
+    callOrder++
+    this.id = this.generateId()
+  }
+
+  /**
+   * Generates a unique MD5 hash based on the database
+   * module location and invocation order. Used to reproducibly
+   * identify a database instance among sibling instances.
+   */
+  private generateId() {
+    const { stack } = new Error()
+    const callFrame = stack?.split('\n')[4]
+    const salt = `${callOrder}-${callFrame?.trim()}`
+    return md5(salt)
   }
 
   getModel(name: string) {
@@ -43,7 +63,7 @@ export class Database<Dictionary extends ModelDictionary> {
     const primaryKey =
       customPrimaryKey || (entity[entity.__primaryKey] as string)
 
-    this.events.emit('create', modelName, entity, customPrimaryKey)
+    this.events.emit('create', this.id, modelName, entity, customPrimaryKey)
 
     return this.getModel(modelName).set(primaryKey, entity)
   }
@@ -61,7 +81,7 @@ export class Database<Dictionary extends ModelDictionary> {
     }
 
     this.create(modelName, nextEntity, nextPrimaryKey as string)
-    this.events.emit('update', modelName, prevEntity, nextEntity)
+    this.events.emit('update', this.id, modelName, prevEntity, nextEntity)
   }
 
   has(modelName: string, primaryKey: PrimaryKeyType) {
@@ -74,7 +94,7 @@ export class Database<Dictionary extends ModelDictionary> {
 
   delete(modelName: string, primaryKey: PrimaryKeyType) {
     this.getModel(modelName).delete(primaryKey)
-    this.events.emit('delete', modelName, primaryKey)
+    this.events.emit('delete', this.id, modelName, primaryKey)
   }
 
   listEntities(modelName: string) {

test/db/events.test.ts

@@ -9,7 +9,8 @@ test('emits the "create" event when a new entity is created', (done) => {
     },
   })
 
-  db.events.on('create', (modelName, entity, primaryKey) => {
+  db.events.on('create', (id, modelName, entity, primaryKey) => {
+    expect(id).toEqual(db.id)
     expect(modelName).toEqual('user')
     expect(entity).toEqual({
       __type: 'user',
@@ -31,7 +32,8 @@ test('emits the "update" event when an existing entity is updated', (done) => {
     },
   })
 
-  db.events.on('update', (modelName, prevEntity, nextEntity) => {
+  db.events.on('update', (id, modelName, prevEntity, nextEntity) => {
+    expect(id).toEqual(db.id)
     expect(modelName).toEqual('user')
     expect(prevEntity).toEqual({
       __type: 'user',
@@ -67,7 +69,8 @@ test('emits the "delete" event when an existing entity is deleted', (done) => {
     },
   })
 
-  db.events.on('delete', (modelName, primaryKey) => {
+  db.events.on('delete', (id, modelName, primaryKey) => {
+    expect(id).toEqual(db.id)
     expect(modelName).toEqual('user')
     expect(primaryKey).toEqual('abc-123')
     done()

yarn.lock

@@ -662,6 +662,13 @@
   resolved "https://registry.yarnpkg.com/@types/json-schema/-/json-schema-7.0.7.tgz#98a993516c859eb0d5c4c8f098317a9ea68db9ad"
   integrity sha512-cxWFQVseBm6O9Gbw1IWb8r6OS4OhSt3hPZLkFApLjM8TEXROBuQGLAH2i2gZpcXdLBIrpXuTDhH7Vbm1iXmNGA==
 
+"@types/md5@^2.3.0":
+  version "2.3.0"
+  resolved "https://registry.yarnpkg.com/@types/md5/-/md5-2.3.0.tgz#3b6a623091160f4dc75be3173e25f2110dc3fa1f"
+  integrity sha512-556YJ7ejzxIqSSxzyGGpctuZOarNZJt/zlEkhmmDc1f/slOEANHuwu2ZX7YaZ40rMiWoxt8GvAhoDpW1cmSy6A==
+  dependencies:
+    "@types/node" "*"
+
 "@types/mime@^1":
   version "1.3.2"
   resolved "https://registry.yarnpkg.com/@types/mime/-/mime-1.3.2.tgz#93e25bf9ee75fe0fd80b594bc4feb0e862111b5a"
@@ -1323,6 +1330,11 @@ chardet@^0.7.0:
   resolved "https://registry.yarnpkg.com/chardet/-/chardet-0.7.0.tgz#90094849f0937f2eedc2425d0d28a9e5f0cbad9e"
   integrity sha512-mT8iDcrh03qDGRRmoA2hmBJnxpllMR+0/0qlzjqZES6NdiWDcZkCNAk4rPFZ9Q85r27unkiNNg8ZOiwZXBHwcA==
 
+[email protected]:
+  version "0.0.2"
+  resolved "https://registry.yarnpkg.com/charenc/-/charenc-0.0.2.tgz#c0a1d2f3a7092e03774bfa83f14c0fc5790a8667"
+  integrity sha1-wKHS86cJLgN3S/qD8UwPxXkKhmc=
+
 chokidar@^3.4.2:
   version "3.4.3"
   resolved "https://registry.yarnpkg.com/chokidar/-/chokidar-3.4.3.tgz#c1df38231448e45ca4ac588e6c79573ba6a57d5b"
@@ -1545,6 +1557,11 @@ cross-spawn@^7.0.0:
     shebang-command "^2.0.0"
     which "^2.0.1"
 
+[email protected]:
+  version "0.0.2"
+  resolved "https://registry.yarnpkg.com/crypt/-/crypt-0.0.2.tgz#88d7ff7ec0dfb86f713dc87bbb42d044d3e6c41b"
+  integrity sha1-iNf/fsDfuG9xPch7u0LQRNPmxBs=
+
 cssom@^0.4.4:
   version "0.4.4"
   resolved "https://registry.yarnpkg.com/cssom/-/cssom-0.4.4.tgz#5a66cf93d2d0b661d80bf6a44fb65f5c2e4e0a10"
@@ -2445,7 +2462,7 @@ is-binary-path@~2.1.0:
   dependencies:
     binary-extensions "^2.0.0"
 
-is-buffer@^1.1.5:
+is-buffer@^1.1.5, is-buffer@~1.1.6:
   version "1.1.6"
   resolved "https://registry.yarnpkg.com/is-buffer/-/is-buffer-1.1.6.tgz#efaa2ea9daa0d7ab2ea13a97b2b8ad51fefbe8be"
   integrity sha512-NcdALwpXkTm5Zvvbk7owOUSvVvBKDgKP5/ewfXEznmQFfs4ZRmanOeKBTjRVjka3QFoN6XJ+9F3USqfHqTaU5w==
@@ -3246,6 +3263,15 @@ map-visit@^1.0.0:
   dependencies:
     object-visit "^1.0.0"
 
+md5@^2.3.0:
+  version "2.3.0"
+  resolved "https://registry.yarnpkg.com/md5/-/md5-2.3.0.tgz#c3da9a6aae3a30b46b7b0c349b87b110dc3bda4f"
+  integrity sha512-T1GITYmFaKuO91vxyoQMFETst+O71VUPEU3ze5GNzDm0OWdP8v1ziTaAEPUr/3kLsY3Sftgz242A1SetQiDL7g==
+  dependencies:
+    charenc "0.0.2"
+    crypt "0.0.2"
+    is-buffer "~1.1.6"
+
 [email protected]:
   version "0.3.0"
   resolved "https://registry.yarnpkg.com/media-typer/-/media-typer-0.3.0.tgz#8710d7af0aa626f8fffa1ce00168545263255748"