import { describe, beforeEach, afterEach, expect } from "vitest";
import { toolHandlers, prologInterface } from "@vpursuit/mcp-server-prolog";
const maybeDescribe = (globalThis as any).HAS_SWIPL ? describe : describe.skip;
maybeDescribe("Ancestor Rules Test", () => {
beforeEach(async () => {
// Use normal timeout for this test
delete process.env.SWI_MCP_QUERY_TIMEOUT_MS;
await prologInterface.stop();
await prologInterface.start();
});
afterEach(async () => {
await prologInterface.stop();
});
it("should handle complete ancestor rules correctly", async () => {
const startTime = Date.now();
// Add parent facts
await toolHandlers.knowledgeBaseAssert({ fact: "parent(tom, bob)" });
await toolHandlers.knowledgeBaseAssert({ fact: "parent(bob, alice)" });
await toolHandlers.knowledgeBaseAssert({ fact: "parent(alice, charlie)" });
// Add the complete ancestor rules (base case + recursive case)
await toolHandlers.knowledgeBaseAssert({ fact: "ancestor(X, Y) :- parent(X, Y)" });
await toolHandlers.knowledgeBaseAssert({ fact: "ancestor(X, Z) :- parent(X, Y), ancestor(Y, Z)" });
// Test direct parent relationship (ground query - should succeed)
let result = await toolHandlers.queryStart({ query: "ancestor(tom, bob)" });
expect(result.isError).toBeFalsy();
result = await toolHandlers.queryNext();
expect(result.isError).toBeFalsy();
expect(result.content[0].text).toMatch(/Solution:\s*true/);
await toolHandlers.queryClose();
// Test transitive relationship (grandparent - ground query)
result = await toolHandlers.queryStart({ query: "ancestor(tom, alice)" });
expect(result.isError).toBeFalsy();
result = await toolHandlers.queryNext();
expect(result.isError).toBeFalsy();
expect(result.content[0].text).toMatch(/Solution:\s*true/);
await toolHandlers.queryClose();
// Test longer chain (great-grandparent - ground query)
result = await toolHandlers.queryStart({ query: "ancestor(tom, charlie)" });
expect(result.isError).toBeFalsy();
result = await toolHandlers.queryNext();
expect(result.isError).toBeFalsy();
expect(result.content[0].text).toMatch(/Solution:\s*true/);
await toolHandlers.queryClose();
// Test finding all ancestors of charlie
result = await toolHandlers.queryStart({ query: "ancestor(X, charlie)" });
expect(result.isError).toBeFalsy();
// Collect all solutions
const ancestors = [];
let currentResult = await toolHandlers.queryNext();
while (!currentResult.isError && currentResult.content[0].text.includes("Solution:")) {
// Extract X value from solution text like "Solution: X = alice, more solutions: true"
const match = currentResult.content[0].text.match(/X\s*=\s*(\w+)/);
if (match) {
ancestors.push(match[1]);
}
try {
currentResult = await toolHandlers.queryNext();
} catch {
break;
}
}
await toolHandlers.queryClose();
// Should find alice, bob, and tom as ancestors of charlie
expect(ancestors).toContain("alice");
expect(ancestors).toContain("bob");
expect(ancestors).toContain("tom");
const elapsed = Date.now() - startTime;
// Should complete quickly without timeout
expect(elapsed).toBeLessThan(5000);
});
it("should handle ancestor queries without infinite loops", async () => {
const startTime = Date.now();
// Add parent facts
await toolHandlers.knowledgeBaseAssert({ fact: "parent(john, mary)" });
await toolHandlers.knowledgeBaseAssert({ fact: "parent(mary, susan)" });
// Add the complete ancestor rules
await toolHandlers.knowledgeBaseAssert({ fact: "ancestor(X, Y) :- parent(X, Y)" });
await toolHandlers.knowledgeBaseAssert({ fact: "ancestor(X, Z) :- parent(X, Y), ancestor(Y, Z)" });
// This query should find solutions without hanging
let result = await toolHandlers.queryStart({ query: "ancestor(john, susan)" });
expect(result.isError).toBeFalsy();
result = await toolHandlers.queryNext();
expect(result.isError).toBeFalsy();
expect(result.content[0].text).toMatch(/Solution:/);
await toolHandlers.queryClose();
// Test query that has no solution (should terminate quickly)
result = await toolHandlers.queryStart({ query: "ancestor(susan, john)" });
expect(result.isError).toBeFalsy();
result = await toolHandlers.queryNext();
expect(result.content[0].text).toMatch(/No more solutions/);
await toolHandlers.queryClose();
const elapsed = Date.now() - startTime;
// Should complete quickly
expect(elapsed).toBeLessThan(2000);
});
});
