tests: Add option to exclude files from imports

Note that these tests were originally made to prevent dead code from
being in the repository, although a proper coverage solution would
likely be more useful long-term.

tests/lib.ts

@@ -31,11 +31,25 @@ async function getImportsInFile(file: string): Promise<string[]> {
   return imports;
 }
 
-export async function assertAllModulesInDirectory(directory: string) {
+/** Assets that all files in a given directory are imported in default.nix.
+ *
+ * @param directory The directory to assert.
+ * @param excludes Files to exclude from assertion. Useful for files imported elsewhere.
+ */
+export async function assertAllModulesInDirectory(
+  directory: string,
+  excludes?: string[],
+) {
   const files = await getFilesInDirectory(`./${directory}`);
   const imports = await getImportsInFile(`./${directory}/default.nix`);
 
   for (const file of files) {
+    const basename = file.split(`${directory}/`)[1];
+
+    if (excludes && excludes.includes(basename)) {
+      continue;
+    }
+
     assert(imports.includes(file));
   }
 }

tests/main.ts

@@ -9,8 +9,20 @@ const dirs = [
   "specializations",
 ];
 
+/** A helper function to return excluded files.
+ *
+ * @param directory The directory to get excludes for.
+ * @returns An array of excluded files for the given directory or undefined.
+ */
+function getExcludes(directory: string): string[] | undefined {
+  switch (directory) {
+    case "packages":
+      return ["hycov.nix"];
+  }
+}
+
 for (const dir of dirs) {
   Deno.test(`imports all modules in ./${dir}`, async () => {
-    await assertAllModulesInDirectory(dir);
+    await assertAllModulesInDirectory(dir, getExcludes(dir));
   });
 }