feat: create a utils to assert a folder exists

src/services/modules/snapshot/snapshot.services.ts

@@ -1,10 +1,7 @@
 import type {snapshot_id} from '@dfinity/ic-management';
 import {encodeSnapshotId} from '@dfinity/ic-management';
 import {Principal} from '@dfinity/principal';
-import {isEmptyString} from '@dfinity/utils';
 import {nextArg} from '@junobuild/cli-tools';
-import {red, yellow} from 'kleur';
-import {existsSync, lstatSync} from 'node:fs';
 import ora from 'ora';
 import {
   deleteCanisterSnapshot,
@@ -13,6 +10,7 @@ import {
 } from '../../../api/ic.api';
 import type {AssetKey} from '../../../types/asset-key';
 import {displaySegment} from '../../../utils/display.utils';
+import {assertNonNullishFolderExists} from '../../../utils/fs.utils';
 import {confirmAndExit} from '../../../utils/prompt.utils';
 import {
   loadSnapshotAndAssertExist,
@@ -131,26 +129,7 @@ export const uploadSnapshot = async ({
   const canisterId = Principal.fromText(cId);
 
   const folder = nextArg({args, option: '--dir'});
-
-  if (isEmptyString(folder)) {
-    console.log(
-      `You did not provide a ${yellow('directory')} that contains metadata.json and chunks to upload.`
-    );
-    return;
-  }
-
-  if (!existsSync(folder)) {
-    console.log(`The directory ${yellow('directory')} does not exist.`);
-    return;
-  }
-
-  if (!lstatSync(folder).isDirectory()) {
-    console.log(red(`${folder} is not a directory.`));
-    return;
-  }
-
-  // TODO: extract assertions
-  // TODO: more assertion like is there a metadata.json and chunk files
+  assertNonNullishFolderExists(folder);
 
   const {snapshotId} = await loadSnapshotAndAssertOverwrite({canisterId, segment});
 

src/utils/fs.utils.ts

@@ -1,5 +1,6 @@
-import {yellow} from 'kleur';
-import {existsSync} from 'node:fs';
+import {isEmptyString} from '@dfinity/utils';
+import {red, yellow} from 'kleur';
+import {existsSync, lstatSync} from 'node:fs';
 import {copyFile as fsCopyFile, readFile} from 'node:fs/promises';
 import {dirname, join, relative} from 'node:path';
 import {fileURLToPath} from 'node:url';
@@ -47,3 +48,24 @@ export const readTemplateFile = async ({
 }): Promise<string> => {
   return await readFile(join(__dirname, sourceFolder, template), 'utf-8');
 };
+
+export const assertNonNullishFolderExists: (
+  folder?: string
+) => asserts folder is NonNullable<string> = (folder?: string): void => {
+  if (isEmptyString(folder)) {
+    console.log(
+      `You did not provide a ${yellow('directory')} that contains metadata.json and chunks to upload.`
+    );
+    process.exit(1);
+  }
+
+  if (!existsSync(folder)) {
+    console.log(`The directory ${yellow('directory')} does not exist.`);
+    process.exit(1);
+  }
+
+  if (!lstatSync(folder).isDirectory()) {
+    console.log(red(`${folder} is not a directory.`));
+    process.exit(1);
+  }
+};