feat: add container strategies

npm/ng-packs/packages/core/src/lib/strategies/container.strategy.ts

@@ -0,0 +1,44 @@
+import { ViewContainerRef } from '@angular/core';
+
+export abstract class ContainerStrategy {
+  constructor(public containerRef: ViewContainerRef) {}
+
+  abstract getIndex(): number;
+
+  prepare(): void {}
+}
+
+export class ClearContainerStrategy extends ContainerStrategy {
+  getIndex(): number {
+    return 0;
+  }
+
+  prepare() {
+    this.containerRef.clear();
+  }
+}
+
+export class InsertIntoContainerStrategy extends ContainerStrategy {
+  constructor(containerRef: ViewContainerRef, private index: number) {
+    super(containerRef);
+  }
+
+  getIndex() {
+    return Math.min(Math.max(0, this.index), this.containerRef.length);
+  }
+}
+
+export const CONTAINER_STRATEGY = {
+  Clear(containerRef: ViewContainerRef) {
+    return new ClearContainerStrategy(containerRef);
+  },
+  Append(containerRef: ViewContainerRef) {
+    return new InsertIntoContainerStrategy(containerRef, containerRef.length);
+  },
+  Prepend(containerRef: ViewContainerRef) {
+    return new InsertIntoContainerStrategy(containerRef, 0);
+  },
+  Insert(containerRef: ViewContainerRef, index: number) {
+    return new InsertIntoContainerStrategy(containerRef, index);
+  },
+};

npm/ng-packs/packages/core/src/lib/strategies/index.ts

@@ -1,3 +1,4 @@
+export * from './container.strategy';
 export * from './content-security.strategy';
 export * from './content.strategy';
 export * from './context.strategy';

npm/ng-packs/packages/core/src/lib/tests/container.strategy.spec.ts

@@ -0,0 +1,80 @@
+import { ViewContainerRef } from '@angular/core';
+import {
+  ClearContainerStrategy,
+  CONTAINER_STRATEGY,
+  InsertIntoContainerStrategy,
+} from '../strategies';
+
+describe('ClearContainerStrategy', () => {
+  const containerRef = ({
+    clear: jest.fn(),
+    length: 7,
+  } as any) as ViewContainerRef;
+
+  describe('#getIndex', () => {
+    it('should return 0', () => {
+      const strategy = new ClearContainerStrategy(containerRef);
+      expect(strategy.getIndex()).toBe(0);
+    });
+  });
+
+  describe('#prepare', () => {
+    it('should call clear method of containerRef once', () => {
+      const strategy = new ClearContainerStrategy(containerRef);
+      strategy.prepare();
+      expect(strategy.getIndex()).toBe(0);
+      expect(containerRef.clear).toHaveBeenCalledTimes(1);
+    });
+  });
+});
+
+describe('InsertIntoContainerStrategy', () => {
+  const containerRef = ({
+    clear: jest.fn(),
+    length: 7,
+  } as any) as ViewContainerRef;
+
+  describe('#getIndex', () => {
+    test.each`
+      index       | expected
+      ${0}        | ${0}
+      ${4}        | ${4}
+      ${9}        | ${7}
+      ${-1}       | ${0}
+      ${Infinity} | ${7}
+    `(
+      'should return $expected when index is given $index',
+      ({ index, expected }: { index: number; expected: number }) => {
+        const strategy = new InsertIntoContainerStrategy(containerRef, index);
+        expect(strategy.getIndex()).toBe(expected);
+      },
+    );
+  });
+
+  describe('#prepare', () => {
+    it('should not call clear method of containerRef', () => {
+      const strategy = new InsertIntoContainerStrategy(containerRef, 0);
+      strategy.prepare();
+      expect(containerRef.clear).not.toHaveBeenCalled();
+    });
+  });
+});
+
+describe('CONTAINER_STRATEGY', () => {
+  const containerRef = ({
+    clear: jest.fn(),
+    length: 7,
+  } as any) as ViewContainerRef;
+
+  test.each`
+    name         | Strategy                       | index
+    ${'Clear'}   | ${ClearContainerStrategy}      | ${undefined}
+    ${'Append'}  | ${InsertIntoContainerStrategy} | ${containerRef.length}
+    ${'Prepend'} | ${InsertIntoContainerStrategy} | ${0}
+    ${'Insert'}  | ${InsertIntoContainerStrategy} | ${4}
+  `('should successfully map $name to $Strategy.name', ({ name, Strategy, index }) => {
+    expect(CONTAINER_STRATEGY[name](containerRef, index)).toEqual(
+      new Strategy(containerRef, index),
+    );
+  });
+});