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Testing your integration

Never touch the real key​

Point PSEUDONYM_HOME to a new temporary folder before your tests call the library. Each folder gets its own key and directory. With node:test (any test runner works the same way):

import { mkdtempSync } from "node:fs";
import { tmpdir } from "node:os";
import path from "node:path";
import { beforeEach } from "node:test";

beforeEach(() => {
  process.env.PSEUDONYM_HOME = mkdtempSync(path.join(tmpdir(), "pseudonym-"));
});

The library reads PSEUDONYM_HOME on every call, so setting it in beforeEach is enough. Child processes you spawn need it in their environment too.

Don't assert on fixed aliases​

Each temporary folder has a new random key, so aliases change between runs. Assert on their shape, or compare two calls:

const ALIAS = /^A-[0-9A-HJKMNP-TV-Z]{6,12}$/;

const [a] = await remember([person]);
assert.match(a, ALIAS);
assert.equal(await remember(person), a); // stable within the same folder

Assert that nothing personal leaks​

The most useful test of an integration: call your tools and check that no personal value from your fixtures appears in their output.

const personal = students.flatMap((s) => [s.fullName, s.email, s.studentNumber, String(s.id)]);

const output = await callTool("list_students");
for (const value of personal) assert.ok(!output.includes(value), `leaked: ${value}`);

Use invented data in fixtures: invented names, and domains such as example.test or example-school.test.

Test the way back​

For write tools, check that an alias from one tool resolves to the right record, and that an unknown alias is a readable error:

const [{ student }] = JSON.parse(await callTool("list_students"));
await callTool("grade_student", { student, grade: 6 });
assert.equal(gradebook.get(students[0].id), 6);

const result = await callTool("grade_student", { student: "A-000000", grade: 5 });
assert.equal(result.isError, true);

The classroom example's test does all of this through MCP, with an in-process client.