/**
* Tests for MCP image content block response formatting
*/
import { describe, it, expect } from "vitest";
/**
* This tests the server response transformation logic for image content blocks.
* The actual logic in server.ts:
*
* if (result && typeof result === "object" && "base64" in result && "mimeType" in result) {
* const { base64, mimeType, ...metadata } = result;
* return {
* content: [
* { type: "image", data: base64, mimeType },
* { type: "text", text: JSON.stringify(metadata, null, 2) },
* ],
* };
* }
*/
// Replicate the server logic for testing
function formatToolResponse(result: unknown) {
if (result && typeof result === "object" && "base64" in result && "mimeType" in result) {
const { base64, mimeType, ...metadata } = result as { base64: string; mimeType: string; [key: string]: unknown };
return {
content: [
{ type: "image", data: base64, mimeType },
{ type: "text", text: JSON.stringify(metadata, null, 2) },
],
};
}
return {
content: [{ type: "text", text: JSON.stringify(result, null, 2) }],
};
}
describe("Image Content Block Response Formatting", () => {
it("should return image content blocks for results with base64 and mimeType", () => {
const mockBase64 = "iVBORw0KGgoAAAANSUhEUgAAAAEAAAABCAYAAAAfFcSJAAAADUlEQVR42mNk+M9QDwADhgGAWjR9awAAAABJRU5ErkJggg==";
const screenshotResult = {
mode: "inline",
base64: mockBase64,
mimeType: "image/png",
sizeBytes: 68,
device: { width: 1080, height: 2400 },
image: { width: 450, height: 1000 },
scaleFactor: 2.4,
deviceId: "emulator-5554",
};
const response = formatToolResponse(screenshotResult);
// Should have 2 content blocks: image + metadata
expect(response.content).toHaveLength(2);
// First block should be the image
const imageBlock = response.content[0];
expect(imageBlock.type).toBe("image");
expect((imageBlock as { data: string }).data).toBe(mockBase64);
expect((imageBlock as { mimeType: string }).mimeType).toBe("image/png");
// Second block should be metadata (without base64/mimeType)
const textBlock = response.content[1];
expect(textBlock.type).toBe("text");
const metadata = JSON.parse((textBlock as { text: string }).text);
expect(metadata.base64).toBeUndefined();
expect(metadata.mimeType).toBeUndefined();
expect(metadata.mode).toBe("inline");
expect(metadata.sizeBytes).toBe(68);
expect(metadata.scaleFactor).toBe(2.4);
expect(metadata.deviceId).toBe("emulator-5554");
});
it("should return text-only for results without base64", () => {
const result = { message: "success", count: 5 };
const response = formatToolResponse(result);
expect(response.content).toHaveLength(1);
expect(response.content[0].type).toBe("text");
});
it("should return text-only for results without mimeType", () => {
const result = { base64: "abc123", data: "something" };
const response = formatToolResponse(result);
expect(response.content).toHaveLength(1);
expect(response.content[0].type).toBe("text");
});
it("should return text-only for null result", () => {
const response = formatToolResponse(null);
expect(response.content).toHaveLength(1);
expect(response.content[0].type).toBe("text");
});
it("should return text-only for primitive result", () => {
const response = formatToolResponse("hello");
expect(response.content).toHaveLength(1);
expect(response.content[0].type).toBe("text");
});
it("should handle JPEG screenshots", () => {
const result = {
base64: "/9j/4AAQSkZJRg==",
mimeType: "image/jpeg",
sizeBytes: 15540,
};
const response = formatToolResponse(result);
expect(response.content).toHaveLength(2);
expect(response.content[0].type).toBe("image");
expect((response.content[0] as { mimeType: string }).mimeType).toBe("image/jpeg");
});
});
