feat: Container.hasToken() for checking token presence.

packages/ditox/lib/index.d.ts

@@ -72,6 +72,10 @@ declare type Container = {
      * Binds a factory for the token.
      */
     bindFactory<T>(token: Token<T>, factory: (container: Container) => T, options?: FactoryOptions<T>): void;
+    /**
+     * Checks if the token is registered in the container hierarchy.
+     */
+    hasToken(token: Token<unknown>): boolean;
     /**
      * Returns a resolved value by the token, or returns `undefined` in case the token is not found.
      */

packages/ditox/src/ditox.js.flow

@@ -95,10 +95,16 @@ export type Container = {
     options?: FactoryOptions<T>,
   ): void,
 
+  /**
+   * Checks if the token is registered in the container hierarchy.
+   */
+  hasToken(token: Token<*>): boolean;
+
   /**
    * Returns a resolved value by the token, or returns `undefined` in case the token is not found.
    */
   get<T>(token: Token<T>): T | void,
+
   /**
    * Returns a resolved value by the token, or throws `ResolverError` in case the token is not found.
    */
@@ -108,6 +114,7 @@ export type Container = {
    * Removes a binding for the token.
    */
   remove<T>(token: Token<T>): void,
+
   /**
    * Removes all bindings in the container.
    */

packages/ditox/src/ditox.test.ts

@@ -390,6 +390,35 @@ describe('Container', () => {
     });
   });
 
+  describe('hasToken()', () => {
+    it('should check if a container hierarchy has the token', () => {
+      const factory = jest.fn();
+
+      const token1 = token();
+      const token2 = token();
+      const token3 = token();
+
+      const parent = createContainer();
+      parent.bindValue(token1, 1);
+      parent.bindFactory(token2, factory);
+
+      expect(parent.hasToken(token1)).toBe(true);
+      expect(parent.hasToken(token2)).toBe(true);
+      expect(parent.hasToken(token3)).toBe(false);
+
+      const child = createContainer(parent);
+      expect(child.hasToken(token1)).toBe(true);
+      expect(child.hasToken(token2)).toBe(true);
+      expect(child.hasToken(token3)).toBe(false);
+
+      child.bindValue(token3, 2);
+      expect(parent.hasToken(token3)).toBe(false);
+      expect(child.hasToken(token3)).toBe(true);
+
+      expect(factory).toHaveBeenCalledTimes(0);
+    });
+  });
+
   describe('get()', () => {
     it('should return a provided value', () => {
       const container = createContainer();

packages/ditox/src/ditox.ts

@@ -107,6 +107,11 @@ export type Container = {
     options?: FactoryOptions<T>,
   ): void;
 
+  /**
+   * Checks if the token is registered in the container hierarchy.
+   */
+  hasToken(token: Token<unknown>): boolean;
+
   /**
    * Returns a resolved value by the token, or returns `undefined` in case the token is not found.
    */
@@ -247,6 +252,14 @@ export function createContainer(parentContainer?: Container): Container {
       bindInternalTokens();
     },
 
+    hasToken(token: Token<unknown>): boolean {
+      return (
+        values.has(token.symbol) ||
+        factories.has(token.symbol) ||
+        (parentContainer?.hasToken(token) ?? false)
+      );
+    },
+
     get<T>(token: Token<T>): T | undefined {
       const value = resolver(token, container);
       if (value !== NOT_FOUND) {

packages/ditox/test-flow/ditox.test.js

@@ -270,6 +270,35 @@ describe('Container', () => {
     });
   });
 
+  describe('hasToken()', () => {
+    it('should check if a container hierarchy has the token', () => {
+      const factory = jest.fn();
+
+      const token1 = token();
+      const token2 = token();
+      const token3 = token();
+
+      const parent = createContainer();
+      parent.bindValue(token1, 1);
+      parent.bindFactory(token2, factory);
+
+      expect(parent.hasToken(token1)).toBe(true);
+      expect(parent.hasToken(token2)).toBe(true);
+      expect(parent.hasToken(token3)).toBe(false);
+
+      const child = createContainer(parent);
+      expect(child.hasToken(token1)).toBe(true);
+      expect(child.hasToken(token2)).toBe(true);
+      expect(child.hasToken(token3)).toBe(false);
+
+      child.bindValue(token3, 2);
+      expect(parent.hasToken(token3)).toBe(false);
+      expect(child.hasToken(token3)).toBe(true);
+
+      expect(factory).toHaveBeenCalledTimes(0);
+    });
+  });
+
   describe('get()', () => {
     it('should return a provided value', () => {
       const container = createContainer();