ci: type-check in CI instead of leaning on the test runner (#4)

Type checking only happened as a side effect of ts-node compiling test
files on the way in, and it surfaced as an unrelated-looking module
resolution error rather than a type error. CI never called the check-types
script that already existed.

Running the tests transpile-only and type checking as its own step splits
the two concerns, but tsconfig.json excludes the test tree so that tsup
emits declarations for src alone. Checking that config by itself would
have left test files unchecked by anything, so a second config covers
them, and check-types runs both.

Author: robrigo

.github/workflows/ci.yml

@@ -24,6 +24,12 @@ jobs:
       - name: Install
         run: yarn install --frozen-lockfile
 
+      # Type-checks src and the test tree. tsconfig.json excludes the test
+      # tree so that tsup emits declarations for src alone, so this needs the
+      # dedicated tsconfig.test.json to cover what that one doesn't.
+      - name: Type check
+        run: yarn run check-types
+
       - name: Build
         run: yarn run build
 

package.json

@@ -47,10 +47,10 @@
   ],
   "scripts": {
     "build": "tsup",
-    "check-types": "tsc --noEmit",
+    "check-types": "tsc --noEmit && tsc --noEmit -p tsconfig.test.json",
     "lint": "eslint .",
     "pretest": "tsup",
-    "test": "mocha -r ts-node/register test/**/*.test.ts",
+    "test": "mocha -r ts-node/register/transpile-only test/**/*.test.ts",
     "prepare": "tsup",
     "prepack": "tsup"
   },

tsconfig.test.json

@@ -0,0 +1,14 @@
+// Type-checks the test tree, plus whatever src files the tests import.
+// tsconfig.json excludes the test tree so that tsup builds and emits
+// declarations for src alone; rootDir widens to the repo root because the
+// test files sit outside src.
+{
+  "extends": "./tsconfig.json",
+  "compilerOptions": {
+    "rootDir": ".",
+    "declaration": false,
+    "noEmit": true
+  },
+  "include": ["test/**/*.ts"],
+  "exclude": ["node_modules"]
+}