feat: add isServiceAvailable method

Author: stephen-carter-at-sf

src/services/serviceProvider.ts

@@ -25,6 +25,19 @@ export class ServiceProvider {
     Map<string, ServiceReturnType<ServiceType>>
   > = new Map();
 
+  /**
+   * Checks if the service is available to be created and returned from the {@link getService} method.
+   * Specifically, this method checks if there even is a command associated with the specified
+   * @{link ServiceType} registered within VS Code.
+   * @param type - The type of the service.
+   * @returns The value true if the service is available and false otherwise.
+   */
+  static async isServiceAvailable<T extends ServiceType>(
+    type: T
+  ): Promise<boolean> {
+    return (await this.getCommands()).includes(this.getCommandString(type));
+  }
+
   /**
    * Retrieves a service instance of the specified type and instance name.
    * If the service instance does not exist, it will be created.
@@ -99,7 +112,7 @@ export class ServiceProvider {
   }
 
   /**
-   * Checks if a service of the specified type exists.
+   * Checks if a service of the specified type exists yet within the cache of the ServiceProvider.
    * @param type - The type of the service.
    * @returns True if the service exists, false otherwise.
    */
@@ -108,7 +121,7 @@ export class ServiceProvider {
   }
 
   /**
-   * Checks if a service instance of the specified type and instance name exists.
+   * Checks if a service instance of the specified type and instance name exists yet within the cache of the ServiceProvider.
    * @param type - The type of the service.
    * @param instanceName - The name of the service instance.
    * @returns True if the service instance exists, false otherwise.

test/services/serviceProvider.test.ts

@@ -110,6 +110,26 @@ describe('ServiceProvider', () => {
     });
   });
 
+  it('should correctly identify that a service is available if the associated command is registered', async () => {
+    const isAvailable = await ServiceProvider.isServiceAvailable(
+      ServiceType.Telemetry
+    );
+    expect(isAvailable).toBe(true);
+  });
+
+  it('should correctly identify that a service is not available if the associated command is not registered', async () => {
+    jest
+      // eslint-disable-next-line @typescript-eslint/no-explicit-any
+      .spyOn(ServiceProvider as any, 'getCommands')
+      .mockImplementation(() => {
+        return Promise.resolve([loggerCommand]);
+      });
+    const isAvailable = await ServiceProvider.isServiceAvailable(
+      ServiceType.Telemetry
+    );
+    expect(isAvailable).toBe(false);
+  });
+
   it('should get a service', async () => {
     (vscode.commands.executeCommand as jest.Mock).mockResolvedValue(
       'mockService'