Merge pull request #749 from balena-io/migrationStatus-type-guard

Use a type guard for `"migration"."migration status"`

package.json

@@ -20,7 +20,7 @@
     "webpack-build": "npm run webpack-browser && npm run webpack-module && npm run webpack-server",
     "lint": "balena-lint -t tsconfig.dev.json -e js -e ts src build typings Gruntfile.ts && npx tsc --project tsconfig.dev.json --noEmit",
     "test": "npm run lint && npm run build && npm run webpack-build && npm run test:compose",
-    "test:compose": "trap 'docker-compose -f docker-compose.npm-test.yml down ; echo Stopped ; exit 0' SIGINT; docker-compose -f docker-compose.npm-test.yml up -d && sleep 2 && DATABASE_URL=postgres://docker:docker@localhost:5431/postgres PINEJS_WEBRESOURCE_MAXFILESIZE=1000000000 S3_ENDPOINT=http://localhost:43680 S3_ACCESS_KEY=USERNAME S3_SECRET_KEY=PASSWORD S3_STORAGE_ADAPTER_BUCKET=balena-pine-web-resources S3_REGION=us-east-1 npm run mocha",
+    "test:compose": "trap 'docker compose -f docker-compose.npm-test.yml down ; echo Stopped ; exit 0' SIGINT; docker compose -f docker-compose.npm-test.yml up -d && sleep 2 && DATABASE_URL=postgres://docker:docker@localhost:5431/postgres PINEJS_WEBRESOURCE_MAXFILESIZE=1000000000 S3_ENDPOINT=http://localhost:43680 S3_ACCESS_KEY=USERNAME S3_SECRET_KEY=PASSWORD S3_STORAGE_ADAPTER_BUCKET=balena-pine-web-resources S3_REGION=us-east-1 npm run mocha",
     "mocha": "TS_NODE_FILES=true mocha",
     "prettify": "balena-lint -t tsconfig.dev.json -e js -e ts --fix src test build typings Gruntfile.ts"
   },

src/migrator/utils.ts

@@ -326,16 +326,27 @@ WHERE "migration"."model name" = ${1}`,
 		return [];
 	}
 
-	/**
-	 * Should be
-	 * 	if ( Array.isArray(executedMigrations) && executedMigrations.every((migration) => typeof migration === 'string') ) {
-	 * 		return executedMigrations;
-	 *  }
-	 * but typescript does not infer that every element of the array is a string
-	 */
-	return sbvrUtils.sbvrTypes.JSON.fetchProcessing(
+	const executedMigrations = sbvrUtils.sbvrTypes.JSON.fetchProcessing(
 		data.executed_migrations,
-	) as string[];
+	);
+	if (!Array.isArray(executedMigrations)) {
+		throw new Error(
+			`"migration"."executed migrations" is expected to be an Array<string>, but the retrieved value was ${typeof executedMigrations}`,
+		);
+	}
+	if (
+		!executedMigrations.every(
+			(migration): migration is string => typeof migration === 'string',
+		)
+	) {
+		const nonStringMigrationValue = executedMigrations.find(
+			(migration) => typeof migration !== 'string',
+		);
+		throw new Error(
+			`"migration"."executed migrations" is expected to be an Array<string>, but the retrieved array included ${typeof nonStringMigrationValue}`,
+		);
+	}
+	return executedMigrations;
 };
 
 export const migrationTablesExist = async (tx: Tx) => {