Restore inotify limits even when a test body throws

The limits were only written back after a successful body, so a
failing limit test left the shared kernel at the lowered values and
every later run failed with ENOSPC. The helper now restores in a
`defer` and can lower a chosen subset of the limits.

Tests/InotifyIntegrationTests/Utilities/withLowInotifyWatchLimit.swift

@@ -1,10 +1,28 @@
 import Foundation
 
-func withInotifyWatchLimit(of limit: Int, _ body: () async throws -> Void) async throws {
+enum InotifyLimit: String, CaseIterable {
+	case userWatches = "max_user_watches"
+	case userInstances = "max_user_instances"
+	case queuedEvents = "max_queued_events"
+}
+
+func withInotifyWatchLimit(
+	of limit: Int,
+	for limits: [InotifyLimit] = InotifyLimit.allCases,
+	_ body: () async throws -> Void
+) async throws {
 	let confPath = URL(filePath: "/proc/sys/fs/inotify")
-	let filenames = ["max_user_watches", "max_user_instances", "max_queued_events"]
+	let filenames = limits.map(\.rawValue)
 	var previousLimits: [String: String] = [:]
 
+	defer {
+		for filename in filenames {
+			let filePath = confPath.appending(path: filename)
+			guard let previousLimit = previousLimits[filename] else { continue }
+			try? previousLimit.write(to: filePath, atomically: false, encoding: .utf8)
+		}
+	}
+
 	for filename in filenames {
 		let filePath = confPath.appending(path: filename)
 		let currentLimit = try String(contentsOf: filePath, encoding: .utf8)
@@ -13,10 +31,4 @@ func withInotifyWatchLimit(of limit: Int, _ body: () async throws -> Void) async
 	}
 
 	try await body()
-
-	for filename in filenames {
-		let filePath = confPath.appending(path: filename)
-		guard let previousLimit = previousLimits[filename] else { continue }
-		try previousLimit.write(to: filePath, atomically: false, encoding: .utf8)
-	}
 }