test: lock in .env.example placeholder-only template (E00-S04-T05)

tests/env-example.test.mjs

@@ -0,0 +1,235 @@
+/**
+ * .env.example test — locks in the [E00-S04-T05] guarantee that the committed
+ * `.env.example` template at the repo root contains placeholders only and no
+ * real secret values.
+ *
+ * Acceptance criteria covered (each test fails without the committed state):
+ *   - ".env.example contains placeholders only" → the file exists at the repo
+ *     root and every assignment value is a placeholder (an explicit
+ *     `change-me`/`<…>`-style marker) or a benign non-secret default (bind
+ *     address, port, local database/user name); no value is a long
+ *     random-looking token without a placeholder marker, no value embeds a
+ *     credential URI, every line is a comment, a blank line, or a well-formed
+ *     `KEY=value` assignment, no variable is repeated, and the file documents
+ *     every configuration environment source (`HOST`/`PORT`/`DATABASE_URL`/
+ *     `EPPP_SESSION_SECRET`).
+ *   - "no real secret values appear in the example file" → the same value
+ *     predicate rejects secret-shaped values, the compose dev-default
+ *     credential value appears nowhere in the file (values or comments), and
+ *     `.gitignore` keeps real `.env` files ignored while un-ignoring the
+ *     committed `.env.example`. The mutation probes below prove the
+ *     assertions are non-vacuous (a secret-looking value, a credential URI, a
+ *     compose default credential, a missing required variable, a dropped
+ *     `!.env.example` negation, or a malformed line all break the criterion).
+ *
+ * Run: `node --test tests/env-example.test.mjs`
+ * (node:test — built into Node >= 18; no dependencies, lockfile untouched.)
+ */
+
+import test from 'node:test';
+import assert from 'node:assert/strict';
+import { existsSync, readFileSync } from 'node:fs';
+import path from 'node:path';
+import { fileURLToPath } from 'node:url';
+
+const REPO_ROOT = path.resolve(path.dirname(fileURLToPath(import.meta.url)), '..');
+
+const read = (relPath) => readFileSync(path.join(REPO_ROOT, relPath), 'utf8');
+const exists = (relPath) => existsSync(path.join(REPO_ROOT, relPath));
+
+const ENV_EXAMPLE_PATH = '.env.example';
+
+/** The config schema's environment sources (E00-S04-T01/T04) the template must document. */
+const REQUIRED_VARS = ['HOST', 'PORT', 'DATABASE_URL', 'EPPP_SESSION_SECRET'];
+
+/** Compose dev-default credential values that must never appear in the template. */
+const FORBIDDEN_VALUES = ['postgres://eppp:eppp@db:5432/eppp'];
+
+/** A long random-looking value (JWT/API-key/token-shaped literal). */
+const LONG_SECRET_RE = /^[A-Za-z0-9+/=_-]{32,}$/;
+
+/** A credential URI (`scheme://user:pass@host`) embedded as a literal value. */
+const CREDENTIAL_URI_RE = /:\/\/[^/\s]+:[^@\s]+@/;
+
+/** Explicit placeholder markers a value may carry. */
+const PLACEHOLDER_MARKERS = [
+  'change-me',
+  'changeme',
+  'change_me',
+  'your-',
+  'replace',
+  'example',
+  'xxx',
+  '<',
+  '>',
+];
+
+/** Benign non-secret defaults the template may show as values. */
+const BENIGN_VALUES = new Set([
+  '0.0.0.0', // HOST container default
+  '3000', // PORT / APP_PORT default
+  '5432', // POSTGRES_PORT default
+  'localhost', // local bind/db host
+  'eppp', // local database/user name (non-secret)
+  'postgres://localhost:5432/eppp', // DATABASE_URL shape without embedded credentials
+]);
+
+/**
+ * True when an assignment value is a placeholder, never a real secret.
+ *
+ * A value is a placeholder when it is a benign non-secret default or carries
+ * an explicit placeholder marker; a marked value is still rejected when it
+ * embeds a credential URI or reproduces a compose default credential. Any
+ * other value — including a long random-looking token — is not a placeholder.
+ */
+function isPlaceholderValue(value) {
+  if (value === '') return false;
+  if (BENIGN_VALUES.has(value)) return true;
+  if (PLACEHOLDER_MARKERS.some((marker) => value.includes(marker))) {
+    return !CREDENTIAL_URI_RE.test(value) && !FORBIDDEN_VALUES.includes(value);
+  }
+  return false;
+}
+
+/**
+ * Parses the template into `{ key, value }` assignments, ignoring blank lines
+ * and `#` comment lines. Throws a descriptive Error on a malformed line so a
+ * stray non-assignment line cannot silently pass.
+ */
+function parseAssignments(content) {
+  const assignments = [];
+  content.split(/\r?\n/).forEach((raw, index) => {
+    const line = raw.trim();
+    if (line === '' || line.startsWith('#')) return;
+    const match = /^([A-Z][A-Z0-9_]*)=(.*)$/.exec(line);
+    if (!match) {
+      throw new Error(
+        `line ${index + 1} is not a comment, blank line, or KEY=value assignment: "${raw}"`,
+      );
+    }
+    assignments.push({ key: match[1], value: match[2] });
+  });
+  return assignments;
+}
+
+/**
+ * Asserts the acceptance criteria for the given template content — used by
+ * the committed-state test and by the mutation probes (which must make it
+ * throw).
+ */
+function assertTemplateHasPlaceholdersOnly(content) {
+  for (const forbidden of FORBIDDEN_VALUES) {
+    assert.ok(
+      !content.includes(forbidden),
+      `the template must not contain the compose default credential value "${forbidden}"`,
+    );
+  }
+
+  const assignments = parseAssignments(content);
+  assert.ok(assignments.length > 0, 'the template must contain at least one assignment');
+
+  const keys = assignments.map(({ key }) => key);
+  assert.equal(new Set(keys).size, keys.length, 'the template must not repeat a variable');
+
+  for (const required of REQUIRED_VARS) {
+    assert.ok(
+      keys.includes(required),
+      `the template must document the required variable "${required}"`,
+    );
+  }
+
+  for (const { key, value } of assignments) {
+    assert.ok(
+      isPlaceholderValue(value),
+      `"${key}" must be a placeholder value, got: "${value}"`,
+    );
+  }
+}
+
+// ---------------------------------------------------------------------------
+// Tests
+// ---------------------------------------------------------------------------
+
+test('a committed .env.example exists at the repo root', () => {
+  assert.ok(exists(ENV_EXAMPLE_PATH), `"${ENV_EXAMPLE_PATH}" must exist at the repo root`);
+});
+
+test('.gitignore keeps real .env files ignored while un-ignoring the committed example', () => {
+  const gitignore = read('.gitignore');
+  assert.ok(gitignore.includes('.env'), 'real .env files must stay git-ignored');
+  assert.ok(gitignore.includes('.env.*'), 'real .env.* files must stay git-ignored');
+  assert.ok(
+    gitignore.includes('!.env.example'),
+    'the committed .env.example must be un-ignored (negation pattern)',
+  );
+});
+
+test('.env.example contains placeholders only and no real secret values', () => {
+  assertTemplateHasPlaceholdersOnly(read(ENV_EXAMPLE_PATH));
+});
+
+// ---------------------------------------------------------------------------
+// Non-vacuous probes — the assertions above really do fail on violations
+// ---------------------------------------------------------------------------
+
+test('a compose default credential value in the template fails the criterion (mutation probe)', () => {
+  const content = read(ENV_EXAMPLE_PATH);
+  const mutated = content.replace(
+    'DATABASE_URL=postgres://localhost:5432/eppp',
+    'DATABASE_URL=postgres://eppp:eppp@db:5432/eppp',
+  );
+  assert.notEqual(mutated, content, 'the mutation must actually replace the DATABASE_URL value');
+  assert.throws(
+    () => assertTemplateHasPlaceholdersOnly(mutated),
+    /compose default credential|placeholder/,
+  );
+});
+
+test('a long secret-looking value fails the criterion (mutation probe)', () => {
+  const content = read(ENV_EXAMPLE_PATH);
+  const mutated = content.replace(
+    'EPPP_SESSION_SECRET=change-me-to-a-random-32-character-secret',
+    'EPPP_SESSION_SECRET=aB3dE9fG0hI1jK2lM3nO4pQ5rS6tU7vW8xY9zA0',
+  );
+  assert.notEqual(mutated, content, 'the mutation must actually replace the session secret');
+  assert.throws(() => assertTemplateHasPlaceholdersOnly(mutated), /placeholder/);
+});
+
+test('a credential URI value fails the criterion (mutation probe)', () => {
+  const content = read(ENV_EXAMPLE_PATH);
+  const mutated = content.replace(
+    'DATABASE_URL=postgres://localhost:5432/eppp',
+    'DATABASE_URL=postgres://alice:supersecret@db.example.com:5432/eppp',
+  );
+  assert.notEqual(mutated, content, 'the mutation must actually replace the DATABASE_URL value');
+  assert.throws(() => assertTemplateHasPlaceholdersOnly(mutated), /placeholder/);
+});
+
+test('a missing required variable fails the criterion (mutation probe)', () => {
+  const content = read(ENV_EXAMPLE_PATH);
+  const mutated = content.replace(/^EPPP_SESSION_SECRET=.*$/m, '');
+  assert.notEqual(
+    mutated,
+    content,
+    'the mutation must actually remove the EPPP_SESSION_SECRET assignment',
+  );
+  assert.throws(() => assertTemplateHasPlaceholdersOnly(mutated), /EPPP_SESSION_SECRET/);
+});
+
+test('dropping the !.env.example negation fails the criterion (mutation probe)', () => {
+  const gitignore = read('.gitignore');
+  const mutated = gitignore.replace('!.env.example', '');
+  assert.notEqual(mutated, gitignore, 'the mutation must actually drop the negation pattern');
+  assert.throws(
+    () => {
+      assert.ok(mutated.includes('!.env.example'), 'the committed .env.example must be un-ignored');
+    },
+    /un-ignored/,
+  );
+});
+
+test('a malformed non-assignment line fails the criterion (mutation probe)', () => {
+  const content = read(ENV_EXAMPLE_PATH);
+  const mutated = `${content}\nTHIS IS NOT A VALID LINE\n`;
+  assert.throws(() => assertTemplateHasPlaceholdersOnly(mutated), /not a comment/);
+});