feat: implement seed method on InMemoryDBService (#53)

* feat: implement seed method on InMemoryDBService

Add new seed method on InMemoryDBService with ability to set amount and record factory for
generation.

Closes #7

Author: wesleygrimes

lib/services/in-memory-db.service.spec.ts

@@ -559,4 +559,38 @@ describe('In Memory DB Service', () => {
       }),
     );
   });
+
+  describe('seed', () => {
+    const recordFactory = (idx: number): Partial<TestEntity> => ({
+      someField: `${idx}`,
+    });
+
+    it.each([[0, 0], [9, 9], [10, 10], [11, 11], [10, null], [10, undefined]])(
+      'should seed %p records given input amount of %p',
+      (expectedAmount: number, inputAmount: number) => {
+        // act
+        service.seed(recordFactory, inputAmount);
+
+        // assert
+        expect(service.records.length).toEqual(expectedAmount);
+      },
+    );
+
+    it.each([[0, 0], [9, 9], [10, 10], [11, 11], [10, null], [10, undefined]])(
+      'should generate correct seed records of %p given input amount of %p',
+      (expectedAmount: number, inputAmount: number) => {
+        // arrange
+        const expectedRecords = [...Array(expectedAmount).keys()].map(i => ({
+          ...recordFactory(i),
+          id: i + 1,
+        }));
+
+        // act
+        service.seed(recordFactory, inputAmount);
+
+        // assert
+        expect(service.records).toEqual(expectedRecords);
+      },
+    );
+  });
 });

lib/services/in-memory-db.service.ts

@@ -296,6 +296,26 @@ export class InMemoryDBService<T extends InMemoryDBEntity> {
     return result$;
   }
 
+  /**
+   * Randomly generate at a set of records for the given amount and record factory.
+   * Example:
+   * ```typescript
+   * service.seed((i) => { myProp: i}, 100);
+   * ```
+   *
+   * @param recordFactory a factory method to call when generating the random record.
+   * @param amount the amount of records to generate, defaults to 10.
+   */
+  public seed(recordFactory: (index: number) => Partial<T>, amount = 10) {
+    amount = amount === null ? 10 : amount;
+
+    const recordsToCreate = [...Array(amount).keys()].map(i =>
+      recordFactory(i),
+    );
+
+    this.createMany(recordsToCreate);
+  }
+
   /**
    * get the next id by finding the max id in the current records array and adding 1 to that value.
    * Example:

package.json

@@ -10,7 +10,7 @@
     "build:dev": "tsc-watch -p tsconfig.json",
     "format": "prettier lib/**/*.ts --write",
     "format:verify": "prettier lib/**/*.ts --check",
-    "lint": "tslint -p tsconfig.json -c tslint.json \"lib/**/*.ts\" -e \"*.spec.ts\"",
+    "lint": "npx tslint -p tsconfig.json -c tslint.json \"lib/**/*.ts\" -e \"*.spec.ts\" --force",
     "test": "jest --config jest.json",
     "semantic-release": "semantic-release",
     "commit": "npx git-cz"
@@ -42,13 +42,16 @@
   "lint-staged": {
     "*.ts": [
       "prettier --write",
-      "git add -f",
+      "git add -f"
+    ],
+    "*.ts,!*.spec.ts": [
       "npm run lint"
     ]
   },
   "husky": {
     "hooks": {
-      "pre-commit": "lint-staged"
+      "pre-commit": "lint-staged",
+      "prepare-commit-msg": "exec < /dev/tty && git cz --hook"
     }
   },
   "publishConfig": {
@@ -67,5 +70,6 @@
       "@semantic-release/npm",
       "@semantic-release/github"
     ]
-  }
+  },
+  "dependencies": {}
 }