MockAdaptor

MockAdaptor implements the whole host bridge in memory. A test needs no real host, no iframe, and no window globals.

import { MockAdaptor } from "ng-mcp-ui/testing";

const adaptor = new MockAdaptor({
  hostContext: { theme: "dark" },
  toolResponses: { cast_vote: { structuredContent: { total: 4 } } },
});

Usually you do not construct it directly. provideMockMcpUi() builds one and returns it with the matching providers.

Constructor arguments

Field	Type	Purpose
hostContext	Partial<HostContext>	Seed values for any subset of the keys. Unset keys take a default.
toolResponses	Record<string, MockToolResponse>	A canned response for each tool name.
serverUrl	string	The value bound to MCP_SERVER_URL. The default is "".

toolResponses

A MockToolResponse is a full CallToolResponse, or just the structuredContent object. The short form is usually enough.

toolResponses: {
  cast_vote: { total: 4 },                                        // short form
  create_poll: { content: [], structuredContent: { id: "1" }, isError: false },
}

The long form needs all three of content, structuredContent and isError. An object that misses one of them counts as the short form, and the whole object becomes the structuredContent. A long form may also carry meta.

A callTool for a name that is not listed resolves with an empty success response. Therefore a wrapper still moves to the success state, and you can test that path without listing every tool.

A canned response with resultType: "input_required" is refused: callTool rejects with an error. A host never surfaces a multi-round trip to a widget, therefore a tool that a view calls has to finish in one round. Keep an elicitation flow on a chat-path tool.

Members

Member	Purpose
calls	The log of every recorded call.
clearCalls()	Empties the log.
pushHostContext(key, value)	Pushes a new value for one key and fires its subscribers.

calls

Each entry is { method, args }. method is a bridge method name, or "registerViewTool:dispose" for a teardown.

expect(adaptor.calls).toContainEqual({
  method: "callTool",
  args: ["cast_vote", { option: "a" }],
});

Call clearCalls() between assertions in a long test.

pushHostContext

This is the counterpart of a real host push. It flips the matching signal in every wrapper that subscribes to that key.

adaptor.pushHostContext("theme", "dark");
// every injectLayout() signal now reports the dark theme

Use it to test how a view reacts to a host change, for example a theme switch or a tool result that arrives late.

Related

• provideMockMcpUi
• Testing widgets