ci: add nightly external contract tests

.github/workflows/external-contracts.yml

@@ -0,0 +1,30 @@
+name: External contracts
+
+on:
+  schedule:
+    - cron: "0 3 * * *"
+  workflow_dispatch:
+
+concurrency:
+  group: ${{ github.workflow }}-${{ github.ref }}
+  cancel-in-progress: true
+
+env:
+  CARGO_PROFILE_TEST_DEBUG: line-tables-only
+  CARGO_INCREMENTAL: 0
+
+jobs:
+  external-contracts:
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@df4cb1c069e1874edd31b4311f1884172cec0e10 # v6
+
+      - uses: dtolnay/rust-toolchain@29eef336d9b2848a0b548edc03f92a220660cdb8 # stable
+
+      - uses: Swatinem/rust-cache@e18b497796c12c097a38f9edb9d0641fb99eee32 # v2
+
+      # These tests intentionally call real third-party APIs. Unit/integration
+      # tests mock providers, but a nightly contract check catches external API
+      # drift that would otherwise only appear at runtime.
+      - name: Run external contract tests
+        run: cargo test --locked --test external_contract -- --ignored --test-threads=1

README.md

@@ -102,6 +102,14 @@ cargo test --locked
 
 The crate denies unsafe code and enables strict Clippy groups: `all`, `pedantic`, `nursery` and `cargo`, with only dependency-version noise allowed.
 
+## External contract checks
+
+Normal tests mock third-party APIs. A scheduled GitHub Actions workflow runs ignored contract tests nightly against the real PokéAPI and FunTranslations APIs to catch provider contract drift early:
+
+```bash
+cargo test --locked --test external_contract -- --ignored --test-threads=1
+```
+
 ## Docker multi-arch build
 
 ```bash

tests/external_contract.rs

@@ -0,0 +1,56 @@
+use pokedex_api::{
+    clients::{funtranslations::TranslationClient, pokeapi::PokeApiClient},
+    domain::TranslationKind,
+};
+use std::time::Duration;
+
+const POKEAPI_BASE_URL: &str = "https://pokeapi.co/api/v2";
+const FUN_TRANSLATIONS_BASE_URL: &str = "https://api.funtranslations.mercxry.me/v1";
+const CONTRACT_TIMEOUT: Duration = Duration::from_secs(10);
+
+#[tokio::test]
+#[ignore = "nightly external contract test: calls the real PokéAPI"]
+async fn pokeapi_species_contract_still_matches_what_we_parse() {
+    let client =
+        PokeApiClient::new(POKEAPI_BASE_URL, CONTRACT_TIMEOUT).expect("client should build");
+
+    let pokemon = client
+        .get_pokemon_info("mewtwo")
+        .await
+        .expect("PokéAPI species contract should still parse");
+
+    assert_eq!(pokemon.name, "mewtwo");
+    assert_eq!(pokemon.habitat, "rare");
+    assert!(pokemon.is_legendary);
+    assert!(!pokemon.description.trim().is_empty());
+}
+
+#[tokio::test]
+#[ignore = "nightly external contract test: calls the real FunTranslations API"]
+async fn funtranslations_yoda_contract_still_matches_what_we_parse() {
+    let client = TranslationClient::new(FUN_TRANSLATIONS_BASE_URL, CONTRACT_TIMEOUT)
+        .expect("client should build");
+
+    let translated = client
+        .translate(TranslationKind::Yoda, "It was created by science.")
+        .await
+        .expect("FunTranslations Yoda contract should still parse");
+
+    assert!(!translated.trim().is_empty());
+    assert_ne!(translated, "It was created by science.");
+}
+
+#[tokio::test]
+#[ignore = "nightly external contract test: calls the real FunTranslations API"]
+async fn funtranslations_shakespeare_contract_still_matches_what_we_parse() {
+    let client = TranslationClient::new(FUN_TRANSLATIONS_BASE_URL, CONTRACT_TIMEOUT)
+        .expect("client should build");
+
+    let translated = client
+        .translate(TranslationKind::Shakespeare, "You have a great friend.")
+        .await
+        .expect("FunTranslations Shakespeare contract should still parse");
+
+    assert!(!translated.trim().is_empty());
+    assert_ne!(translated, "You have a great friend.");
+}