diff --git a/PHP Monitor.xcodeproj/project.pbxproj b/PHP Monitor.xcodeproj/project.pbxproj
index 0373001..7571def 100644
--- a/PHP Monitor.xcodeproj/project.pbxproj	
+++ b/PHP Monitor.xcodeproj/project.pbxproj	
@@ -72,7 +72,7 @@
 		C40FE738282ABA4F00A302C2 /* AppVersion.swift in Sources */ = {isa = PBXBuildFile; fileRef = C40FE736282ABA4F00A302C2 /* AppVersion.swift */; };
 		C40FE73B282ABB2E00A302C2 /* AppVersionTest.swift in Sources */ = {isa = PBXBuildFile; fileRef = C40FE739282ABB2E00A302C2 /* AppVersionTest.swift */; };
 		C412E5FC25700D5300A1FB67 /* HomebrewPackage.swift in Sources */ = {isa = PBXBuildFile; fileRef = C412E5FB25700D5300A1FB67 /* HomebrewPackage.swift */; };
-		C413E43528DA3EB100AE33C7 /* FakeShellTest.swift in Sources */ = {isa = PBXBuildFile; fileRef = C413E43428DA3EB100AE33C7 /* FakeShellTest.swift */; };
+		C413E43528DA3EB100AE33C7 /* TestableShellTest.swift in Sources */ = {isa = PBXBuildFile; fileRef = C413E43428DA3EB100AE33C7 /* TestableShellTest.swift */; };
 		C415937F27A1B54F00D2E1B7 /* PhpFrameworks.swift in Sources */ = {isa = PBXBuildFile; fileRef = C415937E27A1B54F00D2E1B7 /* PhpFrameworks.swift */; };
 		C415938027A1B54F00D2E1B7 /* PhpFrameworks.swift in Sources */ = {isa = PBXBuildFile; fileRef = C415937E27A1B54F00D2E1B7 /* PhpFrameworks.swift */; };
 		C4159AF728E4D40400545349 /* SystemShellTest.swift in Sources */ = {isa = PBXBuildFile; fileRef = C4159AF628E4D40400545349 /* SystemShellTest.swift */; };
@@ -569,6 +569,11 @@
 		C4D366072911331E006BD146 /* EmptyProxyScanner.swift in Sources */ = {isa = PBXBuildFile; fileRef = C4D366052911331E006BD146 /* EmptyProxyScanner.swift */; };
 		C4D366082911331E006BD146 /* EmptyProxyScanner.swift in Sources */ = {isa = PBXBuildFile; fileRef = C4D366052911331E006BD146 /* EmptyProxyScanner.swift */; };
 		C4D366092911331E006BD146 /* EmptyProxyScanner.swift in Sources */ = {isa = PBXBuildFile; fileRef = C4D366052911331E006BD146 /* EmptyProxyScanner.swift */; };
+		C4D3660B29113F20006BD146 /* System.swift in Sources */ = {isa = PBXBuildFile; fileRef = C4D3660A29113F20006BD146 /* System.swift */; };
+		C4D3660C29113F20006BD146 /* System.swift in Sources */ = {isa = PBXBuildFile; fileRef = C4D3660A29113F20006BD146 /* System.swift */; };
+		C4D3660D29113F20006BD146 /* System.swift in Sources */ = {isa = PBXBuildFile; fileRef = C4D3660A29113F20006BD146 /* System.swift */; };
+		C4D3660E29113F20006BD146 /* System.swift in Sources */ = {isa = PBXBuildFile; fileRef = C4D3660A29113F20006BD146 /* System.swift */; };
+		C4D36611291140BE006BD146 /* TestableFileSystemTest.swift in Sources */ = {isa = PBXBuildFile; fileRef = C4D3660F291140BE006BD146 /* TestableFileSystemTest.swift */; };
 		C4D5CFCA27E0F9CD00035329 /* NginxConfigurationFile.swift in Sources */ = {isa = PBXBuildFile; fileRef = C4D5CFC927E0F9CD00035329 /* NginxConfigurationFile.swift */; };
 		C4D5CFCB27E0F9CD00035329 /* NginxConfigurationFile.swift in Sources */ = {isa = PBXBuildFile; fileRef = C4D5CFC927E0F9CD00035329 /* NginxConfigurationFile.swift */; };
 		C4D8016622B1584700C6DA1B /* Startup.swift in Sources */ = {isa = PBXBuildFile; fileRef = C4D8016522B1584700C6DA1B /* Startup.swift */; };
@@ -725,7 +730,7 @@
 		C40FE736282ABA4F00A302C2 /* AppVersion.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = AppVersion.swift; sourceTree = "<group>"; };
 		C40FE739282ABB2E00A302C2 /* AppVersionTest.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = AppVersionTest.swift; sourceTree = "<group>"; };
 		C412E5FB25700D5300A1FB67 /* HomebrewPackage.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = HomebrewPackage.swift; sourceTree = "<group>"; };
-		C413E43428DA3EB100AE33C7 /* FakeShellTest.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = FakeShellTest.swift; sourceTree = "<group>"; };
+		C413E43428DA3EB100AE33C7 /* TestableShellTest.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = TestableShellTest.swift; sourceTree = "<group>"; };
 		C415937E27A1B54F00D2E1B7 /* PhpFrameworks.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = PhpFrameworks.swift; sourceTree = "<group>"; };
 		C4159AF628E4D40400545349 /* SystemShellTest.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = SystemShellTest.swift; sourceTree = "<group>"; };
 		C415D3B62770F294005EF286 /* Actions.swift */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.swift; path = Actions.swift; sourceTree = "<group>"; };
@@ -851,6 +856,8 @@
 		C4CE3BB927B31F670086CA49 /* ComposerWindow.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = ComposerWindow.swift; sourceTree = "<group>"; };
 		C4D36600291132B7006BD146 /* ValetScanners.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = ValetScanners.swift; sourceTree = "<group>"; };
 		C4D366052911331E006BD146 /* EmptyProxyScanner.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = EmptyProxyScanner.swift; sourceTree = "<group>"; };
+		C4D3660A29113F20006BD146 /* System.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = System.swift; sourceTree = "<group>"; };
+		C4D3660F291140BE006BD146 /* TestableFileSystemTest.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = TestableFileSystemTest.swift; sourceTree = "<group>"; };
 		C4D5CFC927E0F9CD00035329 /* NginxConfigurationFile.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = NginxConfigurationFile.swift; sourceTree = "<group>"; };
 		C4D8016522B1584700C6DA1B /* Startup.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = Startup.swift; sourceTree = "<group>"; };
 		C4D89BC52783C99400A02B68 /* ComposerJson.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = ComposerJson.swift; sourceTree = "<group>"; };
@@ -1069,7 +1076,7 @@
 		C413E43328DA3E8F00AE33C7 /* Shell */ = {
 			isa = PBXGroup;
 			children = (
-				C413E43428DA3EB100AE33C7 /* FakeShellTest.swift */,
+				C413E43428DA3EB100AE33C7 /* TestableShellTest.swift */,
 				C4159AF628E4D40400545349 /* SystemShellTest.swift */,
 			);
 			path = Shell;
@@ -1291,6 +1298,7 @@
 		C471E6DA28F9AFCB0021E251 /* Filesystem */ = {
 			isa = PBXGroup;
 			children = (
+				C4D3660F291140BE006BD146 /* TestableFileSystemTest.swift */,
 			);
 			path = Filesystem;
 			sourceTree = "<group>";
@@ -1355,6 +1363,7 @@
 				C41C1B4822B00A9800E7CF16 /* MenuBarImageGenerator.swift */,
 				C4CCBA6B275C567B008C7055 /* PMWindowController.swift */,
 				C4B5635D276AB09000F12CCB /* VersionExtractor.swift */,
+				C4D3660A29113F20006BD146 /* System.swift */,
 			);
 			path = Helpers;
 			sourceTree = "<group>";
@@ -2038,6 +2047,7 @@
 				C4B6091D2853AB9700C95265 /* ServicesView.swift in Sources */,
 				C40508B128ADAB44008FAC1F /* NSMenuItemExtension.swift in Sources */,
 				C4B97B7B275CF20A003F3378 /* App+GlobalHotkey.swift in Sources */,
+				C4D3660B29113F20006BD146 /* System.swift in Sources */,
 				C4D36601291132B7006BD146 /* ValetScanners.swift in Sources */,
 				C4EED88927A48778006D7272 /* InterAppHandler.swift in Sources */,
 				C40C7F1E2772136000DDDCDC /* PhpEnv.swift in Sources */,
@@ -2146,6 +2156,7 @@
 				C471E86A28F9BB650021E251 /* PrefsVC.swift in Sources */,
 				C471E86B28F9BB650021E251 /* PreferenceName.swift in Sources */,
 				C471E86C28F9BB650021E251 /* Preferences.swift in Sources */,
+				C4D3660D29113F20006BD146 /* System.swift in Sources */,
 				C471E86D28F9BB650021E251 /* CustomPrefs.swift in Sources */,
 				C4E2E84C28FC1E70003B070C /* DataExtension.swift in Sources */,
 				C471E86E28F9BB650021E251 /* MenuBarIcons.swift in Sources */,
@@ -2355,6 +2366,7 @@
 				C471E82128F9BB2E0021E251 /* PhpFrameworks.swift in Sources */,
 				C471E7EF28F9BAC30021E251 /* Actions.swift in Sources */,
 				C471E82228F9BB2E0021E251 /* ComposerWindow.swift in Sources */,
+				C4D3660E29113F20006BD146 /* System.swift in Sources */,
 				C471E80428F9BAD40021E251 /* PhpExtension.swift in Sources */,
 				C471E7F728F9BACB0021E251 /* PhpSwitcher.swift in Sources */,
 				C471E82C28F9BB340021E251 /* DomainListable.swift in Sources */,
@@ -2401,7 +2413,7 @@
 				C41CA5EE2774F8EE00A2C80E /* DomainListVC+Actions.swift in Sources */,
 				C4FACE81288F1C0D00FC478F /* PreferencesWindowController+Hotkey.swift in Sources */,
 				54D9E0B727E4F51E003B9AD9 /* HotKey.swift in Sources */,
-				C413E43528DA3EB100AE33C7 /* FakeShellTest.swift in Sources */,
+				C413E43528DA3EB100AE33C7 /* TestableShellTest.swift in Sources */,
 				C4205A7F27F4D21800191A39 /* ValetProxy.swift in Sources */,
 				C42F26742805B4B400938AC7 /* DomainListable.swift in Sources */,
 				C46EBC4528DB95F0007ACC74 /* ShellProtocol.swift in Sources */,
@@ -2505,7 +2517,9 @@
 				C4F7809C25D80344000DBC97 /* CommandTest.swift in Sources */,
 				C44CCD4127AFE2FC00CE40E5 /* AlertableError.swift in Sources */,
 				C4CDA894288F1A71007CE25F /* Keys.swift in Sources */,
+				C4D3660C29113F20006BD146 /* System.swift in Sources */,
 				C4D936CA27E3EB6100BD69FE /* PhpHelper.swift in Sources */,
+				C4D36611291140BE006BD146 /* TestableFileSystemTest.swift in Sources */,
 				C4E2E84B28FC1E70003B070C /* DataExtension.swift in Sources */,
 				C449B4F127EE7FC200C47E8A /* DomainListNameCell.swift in Sources */,
 				C4F780BA25D80B62000DBC97 /* AppDelegate.swift in Sources */,
diff --git a/PHP Monitor.xcodeproj/xcshareddata/xcschemes/PHP Monitor DEV.xcscheme b/PHP Monitor.xcodeproj/xcshareddata/xcschemes/PHP Monitor DEV.xcscheme
index 0b2dcd1..ff88595 100644
--- a/PHP Monitor.xcodeproj/xcshareddata/xcschemes/PHP Monitor DEV.xcscheme	
+++ b/PHP Monitor.xcodeproj/xcshareddata/xcschemes/PHP Monitor DEV.xcscheme	
@@ -80,7 +80,7 @@
          </CommandLineArgument>
          <CommandLineArgument
             argument = "--configuration:~/.phpmon_fconf_working.json"
-            isEnabled = "YES">
+            isEnabled = "NO">
          </CommandLineArgument>
          <CommandLineArgument
             argument = "--configuration:~/.phpmon_fconf_broken.json"
diff --git a/phpmon/Common/Filesystem/FileSystemProtocol.swift b/phpmon/Common/Filesystem/FileSystemProtocol.swift
index cbcf1ec..e1e0fb5 100644
--- a/phpmon/Common/Filesystem/FileSystemProtocol.swift
+++ b/phpmon/Common/Filesystem/FileSystemProtocol.swift
@@ -9,28 +9,36 @@
 import Foundation
 
 protocol FileSystemProtocol {
-    /**
-     Checks if a given path is a file *and* executable.
-     */
+
+    // MARK: - Basics
+
+    func createDirectory(_ path: String, withIntermediateDirectories: Bool) throws
+
+    func writeAtomicallyToFile(_ path: String, content: String) throws
+
+    func readStringFromFile(_ path: String) throws -> String
+
+    // MARK: - Move & Delete Files
+
+    func move(from path: String, to newPath: String) throws
+
+    func remove(_ path: String) throws
+
+    // MARK: — Attributes
+
+    func makeExecutable(_ path: String) throws
+
+    // MARK: - Checks
+
     func isExecutableFile(_ path: String) -> Bool
 
-    /**
-     Checks if a file or directory exists at the provided path.
-     */
-    func exists(_ path: String) -> Bool
+    func isWriteableFile(_ path: String) -> Bool
+
+    func anyExists(_ path: String) -> Bool
 
-    /**
-     Checks if a file exists at the provided path.
-     */
     func fileExists(_ path: String) -> Bool
 
-    /**
-     Checks if a directory exists at the provided path.
-     */
     func directoryExists(_ path: String) -> Bool
 
-    /**
-     Checks if a given file is a symbolic link.
-     */
     func fileIsSymlink(_ path: String) -> Bool
 }
diff --git a/phpmon/Common/Filesystem/RealFileSystem.swift b/phpmon/Common/Filesystem/RealFileSystem.swift
index 601f92b..6d6262f 100644
--- a/phpmon/Common/Filesystem/RealFileSystem.swift
+++ b/phpmon/Common/Filesystem/RealFileSystem.swift
@@ -15,27 +15,67 @@ extension String {
 }
 
 class RealFileSystem: FileSystemProtocol {
-    /**
-     Checks if a given path is a file *and* executable.
-     */
+
+    // MARK: - Basics
+
+    func createDirectory(_ path: String, withIntermediateDirectories: Bool) {
+        try! FileManager.default.createDirectory(
+            atPath: path.replacingTildeWithHomeDirectory,
+            withIntermediateDirectories: withIntermediateDirectories
+        )
+    }
+
+    func writeAtomicallyToFile(_ path: String, content: String) throws {
+        try content.write(
+            to: URL(fileURLWithPath: path.replacingTildeWithHomeDirectory),
+            atomically: true,
+            encoding: String.Encoding.utf8
+        )
+    }
+
+    func readStringFromFile(_ path: String) throws -> String {
+        return try String(
+            contentsOf: URL(fileURLWithPath: path.replacingTildeWithHomeDirectory),
+            encoding: .utf8
+        )
+    }
+
+    // MARK: - Move & Delete Files
+
+    func move(from path: String, to newPath: String) throws {
+        // TODO
+    }
+
+    func remove(_ path: String) throws {
+        // TODO
+    }
+
+    // MARK: — FS Attributes
+
+    func makeExecutable(_ path: String) throws {
+        system("chmod +x \(path.replacingTildeWithHomeDirectory)")
+    }
+
+    // MARK: - Checks
+
     func isExecutableFile(_ path: String) -> Bool {
         return FileManager.default.isExecutableFile(
             atPath: path.replacingTildeWithHomeDirectory
         )
     }
 
-    /**
-     Checks if a file or directory exists at the provided path.
-     */
-    func exists(_ path: String) -> Bool {
+    func isWriteableFile(_ path: String) -> Bool {
+        return FileManager.default.isWritableFile(
+            atPath: path.replacingTildeWithHomeDirectory
+        )
+    }
+
+    func anyExists(_ path: String) -> Bool {
         return FileManager.default.fileExists(
             atPath: path.replacingTildeWithHomeDirectory
         )
     }
 
-    /**
-     Checks if a file exists at the provided path.
-     */
     func fileExists(_ path: String) -> Bool {
         var isDirectory: ObjCBool = true
         let exists = FileManager.default.fileExists(
@@ -46,9 +86,6 @@ class RealFileSystem: FileSystemProtocol {
         return exists && !isDirectory.boolValue
     }
 
-    /**
-     Checks if a directory exists at the provided path.
-     */
     func directoryExists(_ path: String) -> Bool {
         var isDirectory: ObjCBool = true
         let exists = FileManager.default.fileExists(
@@ -59,9 +96,6 @@ class RealFileSystem: FileSystemProtocol {
         return exists && isDirectory.boolValue
     }
 
-    /**
-     Checks if a given file is a symbolic link.
-     */
     func fileIsSymlink(_ path: String) -> Bool {
         do {
             let attribs = try FileManager.default.attributesOfItem(atPath: path)
diff --git a/phpmon/Common/Helpers/System.swift b/phpmon/Common/Helpers/System.swift
new file mode 100644
index 0000000..9b8d000
--- /dev/null
+++ b/phpmon/Common/Helpers/System.swift
@@ -0,0 +1,18 @@
+//
+//  System.swift
+//  PHP Monitor
+//
+//  Created by Nico Verbruggen on 01/11/2022.
+//  Copyright © 2022 Nico Verbruggen. All rights reserved.
+//
+
+import Foundation
+
+public func system(_ command: String) {
+    let argsArray = command.split(separator: " ").map { String($0) }
+    guard argsArray.isEmpty else { return  }
+    let command = strdup(argsArray.first!)
+    let args = argsArray.map { strdup($0) } + [nil]
+    posix_spawn(nil, command, nil, nil, args, nil)
+    return
+}
diff --git a/phpmon/Common/PHP/PHP Version/PhpHelper.swift b/phpmon/Common/PHP/PHP Version/PhpHelper.swift
index 28a200b..4e1ce7b 100644
--- a/phpmon/Common/PHP/PHP Version/PhpHelper.swift	
+++ b/phpmon/Common/PHP/PHP Version/PhpHelper.swift	
@@ -23,12 +23,15 @@ class PhpHelper {
         let inPath = Shell.PATH.contains("\(Paths.homePath)/.config/phpmon/bin")
 
         // Check if we can create symlinks (`/usr/local/bin` must be writable)
-        let canWriteSymlinks = FileManager.default.isWritableFile(atPath: "/usr/local/bin/")
+        let canWriteSymlinks = FileSystem.isWriteableFile("/usr/local/bin/")
 
         Task { // Create the appropriate folders and check if the files exist
             do {
                 if !FileSystem.directoryExists("~/.config/phpmon/bin") {
-                    await Shell.quiet("mkdir -p ~/.config/phpmon/bin")
+                    try FileSystem.createDirectory(
+                        "~/.config/phpmon/bin",
+                        withIntermediateDirectories: true
+                    )
                 }
 
                 if FileSystem.fileExists(destination) {
@@ -56,17 +59,10 @@ class PhpHelper {
                     export PATH=\(path):$PATH
                     """
 
-                // Write to the destination
-                // TODO: Use FileSystem abstraction
-                try script.write(
-                    to: URL(fileURLWithPath: destination),
-                    atomically: true,
-                    encoding: String.Encoding.utf8
-                )
+                try FileSystem.writeAtomicallyToFile(destination, content: script)
 
-                // Make sure the file is executable
                 if !FileSystem.isExecutableFile(destination) {
-                    await Shell.quiet("chmod +x \(destination)")
+                   try FileSystem.makeExecutable(destination)
                 }
 
                 // Create a symlink if the folder is not in the PATH
diff --git a/phpmon/Common/PHP/Switcher/InternalSwitcher.swift b/phpmon/Common/PHP/Switcher/InternalSwitcher.swift
index 372c0cb..f6d9374 100644
--- a/phpmon/Common/PHP/Switcher/InternalSwitcher.swift
+++ b/phpmon/Common/PHP/Switcher/InternalSwitcher.swift
@@ -74,22 +74,22 @@ class InternalSwitcher: PhpSwitcher {
 
     func requiresDisablingOfDefaultPhpFpmPool(_ version: String) -> Bool {
         let pool = "\(Paths.etcPath)/php/\(version)/php-fpm.d/www.conf"
-        return FileManager.default.fileExists(atPath: pool)
+        return FileSystem.fileExists(pool)
     }
 
     func disableDefaultPhpFpmPool(_ version: String) async {
         let pool = "\(Paths.etcPath)/php/\(version)/php-fpm.d/www.conf"
-        if FileManager.default.fileExists(atPath: pool) {
+        if FileSystem.fileExists(pool) {
             Log.info("A default `www.conf` file was found in the php-fpm.d directory for PHP \(version).")
-            let existing = URL(string: "file://\(Paths.etcPath)/php/\(version)/php-fpm.d/www.conf")!
-            let new = URL(string: "file://\(Paths.etcPath)/php/\(version)/php-fpm.d/www.conf.disabled-by-phpmon")!
+            let existing = "\(Paths.etcPath)/php/\(version)/php-fpm.d/www.conf"
+            let new = "\(Paths.etcPath)/php/\(version)/php-fpm.d/www.conf.disabled-by-phpmon"
             do {
-                if FileManager.default.fileExists(atPath: new.path) {
+                if FileSystem.fileExists(new) {
                     Log.info("A moved `www.conf.disabled-by-phpmon` file was found for PHP \(version), "
                              + "cleaning up so the newer `www.conf` can be moved again.")
-                    try FileManager.default.removeItem(at: new)
+                    try FileSystem.remove(new)
                 }
-                try FileManager.default.moveItem(at: existing, to: new)
+                try FileSystem.move(from: existing, to: new)
                 Log.info("Success: A default `www.conf` file was disabled for PHP \(version).")
             } catch {
                 Log.err(error)
diff --git a/phpmon/Common/Testables/TestableFileSystem.swift b/phpmon/Common/Testables/TestableFileSystem.swift
index ca6f41b..b3f425d 100644
--- a/phpmon/Common/Testables/TestableFileSystem.swift
+++ b/phpmon/Common/Testables/TestableFileSystem.swift
@@ -15,6 +15,54 @@ class TestableFileSystem: FileSystemProtocol {
 
     var files: [String: FakeFile]
 
+    // MARK: - Basics
+
+    func createDirectory(_ path: String, withIntermediateDirectories: Bool) throws {
+        if files[path] != nil {
+            throw TestableFileSystemError.alreadyExists
+        }
+
+        self.files[path] = .fake(.directory)
+    }
+
+    func writeAtomicallyToFile(_ path: String, content: String) throws {
+        if files[path] != nil {
+            throw TestableFileSystemError.alreadyExists
+        }
+
+        self.files[path] = .fake(.text, content)
+    }
+
+    func readStringFromFile(_ path: String) throws -> String {
+        guard let file = files[path] else {
+            throw TestableFileSystemError.fileMissing
+        }
+
+        return file.content ?? ""
+    }
+
+    // MARK: - Move & Delete Files
+
+    func move(from path: String, to newPath: String) throws {
+        // TODO
+    }
+
+    func remove(_ path: String) throws {
+        // TODO
+    }
+
+    // MARK: — Attributes
+
+    func makeExecutable(_ path: String) throws {
+        guard let file = files[path] else {
+            throw TestableFileSystemError.fileMissing
+        }
+
+        file.type = .binary
+    }
+
+    // MARK: - Checks
+
     func isExecutableFile(_ path: String) -> Bool {
         guard let file = files[path] else {
             return false
@@ -23,7 +71,15 @@ class TestableFileSystem: FileSystemProtocol {
         return file.type == .binary
     }
 
-    func exists(_ path: String) -> Bool {
+    func isWriteableFile(_ path: String) -> Bool {
+        guard let file = files[path] else {
+            return false
+        }
+
+        return !file.readOnly
+    }
+
+    func anyExists(_ path: String) -> Bool {
         return files.keys.contains(path)
     }
 
@@ -56,11 +112,31 @@ enum FakeFileType: Codable {
     case binary, text, directory, symlink
 }
 
-struct FakeFile: Codable {
+class FakeFile: Codable {
     var type: FakeFileType
     var content: String?
+    var readOnly: Bool = false
 
-    public static func fake(_ type: FakeFileType, _ content: String? = nil) -> FakeFile {
-        return FakeFile(type: type, content: content)
+    init(type: FakeFileType, content: String?, readOnly: Bool = false) {
+        self.type = type
+        self.content = content
+        self.readOnly = readOnly
+    }
+
+    public static func fake(
+        _ type: FakeFileType,
+        _ content: String? = nil,
+        readOnly: Bool = false
+    ) -> FakeFile {
+        return FakeFile(
+            type: type,
+            content: content,
+            readOnly: readOnly
+        )
     }
 }
+
+enum TestableFileSystemError: Error {
+    case fileMissing
+    case alreadyExists
+}
diff --git a/phpmon/Domain/DomainList/AddSiteVC.swift b/phpmon/Domain/DomainList/AddSiteVC.swift
index a427613..17fd285 100644
--- a/phpmon/Domain/DomainList/AddSiteVC.swift
+++ b/phpmon/Domain/DomainList/AddSiteVC.swift
@@ -55,7 +55,7 @@ class AddSiteVC: NSViewController, NSTextFieldDelegate {
         let path = pathControl.url!.path
         let name = inputDomainName.stringValue
 
-        if !FileSystem.exists(path) {
+        if !FileSystem.anyExists(path) {
             Alert.confirm(
                 onWindow: view.window!,
                 messageText: "domain_list.alert.folder_missing.title".localized,
diff --git a/phpmon/Domain/Integrations/Composer/PhpFrameworks.swift b/phpmon/Domain/Integrations/Composer/PhpFrameworks.swift
index 2de9176..dd66bdc 100644
--- a/phpmon/Domain/Integrations/Composer/PhpFrameworks.swift
+++ b/phpmon/Domain/Integrations/Composer/PhpFrameworks.swift
@@ -71,7 +71,7 @@ struct PhpFrameworks {
     public static func detectFallbackDependency(_ basePath: String) -> String? {
         for entry in Self.FileMapping {
             let found = entry.value
-                .map { path in return FileSystem.exists(basePath + path) }
+                .map { path in return FileSystem.anyExists(basePath + path) }
                 .contains(true)
 
             if found {
diff --git a/phpmon/Domain/Integrations/Valet/Valet.swift b/phpmon/Domain/Integrations/Valet/Valet.swift
index 5b11982..2bdc6fe 100644
--- a/phpmon/Domain/Integrations/Valet/Valet.swift
+++ b/phpmon/Domain/Integrations/Valet/Valet.swift
@@ -98,13 +98,10 @@ class Valet {
      If the JSON is invalid when the app launches, an alert will be presented, however.
      */
     public func loadConfiguration() {
-        let file = FileManager.default.homeDirectoryForCurrentUser
-            .appendingPathComponent(".config/valet/config.json")
-
         do {
             config = try JSONDecoder().decode(
                 Valet.Configuration.self,
-                from: try String(contentsOf: file, encoding: .utf8).data(using: .utf8)!
+                from: FileSystem.readStringFromFile("~/.config/valet/config.json").data(using: .utf8)!
             )
         } catch {
             Log.err(error)
diff --git a/phpmon/Domain/Watcher/PhpConfigWatcher.swift b/phpmon/Domain/Watcher/PhpConfigWatcher.swift
index 37d006b..fc00cc3 100644
--- a/phpmon/Domain/Watcher/PhpConfigWatcher.swift
+++ b/phpmon/Domain/Watcher/PhpConfigWatcher.swift
@@ -51,7 +51,7 @@ class PhpConfigWatcher {
         eventMask: DispatchSource.FileSystemEvent,
         behaviour: FSWatcherBehaviour = .reloadsMenu
     ) {
-        if !FileSystem.exists(url.path) {
+        if !FileSystem.anyExists(url.path) {
             Log.warn("No watcher was created for \(url.path) because the requested file does not exist.")
             return
         }
diff --git a/tests/Shared/TestableConfigurations.swift b/tests/Shared/TestableConfigurations.swift
index 05f00e4..28374d1 100644
--- a/tests/Shared/TestableConfigurations.swift
+++ b/tests/Shared/TestableConfigurations.swift
@@ -14,6 +14,8 @@ class TestableConfigurations {
         return TestableConfiguration(
             architecture: "arm64",
             filesystem: [
+                "/usr/local/bin/"
+                    : .fake(.directory, readOnly: true),
                 "/opt/homebrew/bin/brew"
                     : .fake(.binary),
                 "/opt/homebrew/bin/php"
@@ -30,10 +32,21 @@ class TestableConfigurations {
                     : .fake(.binary),
                 "/opt/homebrew/Cellar/php/8.1.10_1/bin/php-config"
                     : .fake(.binary),
-                "~/.config/valet"
+                "/Users/user/.config/valet"
                     : .fake(.directory),
+                "/Users/user/.config/valet/config.json"
+                    : .fake(.text, """
+                    {
+                    "tld": "test",
+                    "paths": [
+                        "/Users/user/.config/valet/Sites",
+                        "/Users/user/Sites"
+                    ],
+                        "loopback": "127.0.0.1"
+                    }
+                    """),
                 "/opt/homebrew/etc/php/8.1/php-fpm.d/valet-fpm.conf"
-                    : .fake(.text)
+                    : .fake(.text),
             ],
             shellOutput: [
                 "sysctl -n sysctl.proc_translated"
diff --git a/tests/Shared/Utility.swift b/tests/Shared/Utility.swift
index abf2b78..3caa4ec 100644
--- a/tests/Shared/Utility.swift
+++ b/tests/Shared/Utility.swift
@@ -1,6 +1,6 @@
 //
 //  Utility.swift
-//  phpmon-tests
+//  PHP Monitor
 //
 //  Created by Nico Verbruggen on 14/02/2021.
 //  Copyright © 2022 Nico Verbruggen. All rights reserved.
diff --git a/tests/unit/Commands/CommandTest.swift b/tests/unit/Commands/CommandTest.swift
index d5ea2b6..1241bf2 100644
--- a/tests/unit/Commands/CommandTest.swift
+++ b/tests/unit/Commands/CommandTest.swift
@@ -1,6 +1,6 @@
 //
 //  CommandTest.swift
-//  phpmon-tests
+//  PHP Monitor
 //
 //  Created by Nico Verbruggen on 13/02/2021.
 //  Copyright © 2022 Nico Verbruggen. All rights reserved.
diff --git a/tests/unit/Parsers/HomebrewPackageTest.swift b/tests/unit/Parsers/HomebrewPackageTest.swift
index f6a30f7..81c9718 100644
--- a/tests/unit/Parsers/HomebrewPackageTest.swift
+++ b/tests/unit/Parsers/HomebrewPackageTest.swift
@@ -1,6 +1,6 @@
 //
 //  BrewJsonParserTest.swift
-//  phpmon-tests
+//  PHP Monitor
 //
 //  Created by Nico Verbruggen on 14/02/2021.
 //  Copyright © 2022 Nico Verbruggen. All rights reserved.
diff --git a/tests/unit/Parsers/NginxConfigurationTest.swift b/tests/unit/Parsers/NginxConfigurationTest.swift
index 07fa2a3..b09175c 100644
--- a/tests/unit/Parsers/NginxConfigurationTest.swift
+++ b/tests/unit/Parsers/NginxConfigurationTest.swift
@@ -1,6 +1,6 @@
 //
 //  NginxConfigurationTest.swift
-//  phpmon-tests
+//  PHP Monitor
 //
 //  Created by Nico Verbruggen on 29/11/2021.
 //  Copyright © 2022 Nico Verbruggen. All rights reserved.
diff --git a/tests/unit/Parsers/PhpExtensionTest.swift b/tests/unit/Parsers/PhpExtensionTest.swift
index 0bbebc2..2647559 100644
--- a/tests/unit/Parsers/PhpExtensionTest.swift
+++ b/tests/unit/Parsers/PhpExtensionTest.swift
@@ -1,6 +1,6 @@
 //
 //  ExtensionParserTest.swift
-//  phpmon-tests
+//  PHP Monitor
 //
 //  Created by Nico Verbruggen on 13/02/2021.
 //  Copyright © 2022 Nico Verbruggen. All rights reserved.
diff --git a/tests/unit/Parsers/ValetConfigurationTest.swift b/tests/unit/Parsers/ValetConfigurationTest.swift
index e640177..5b57fe9 100644
--- a/tests/unit/Parsers/ValetConfigurationTest.swift
+++ b/tests/unit/Parsers/ValetConfigurationTest.swift
@@ -1,6 +1,6 @@
 //
 //  ValetConfigParserTest.swift
-//  phpmon-tests
+//  PHP Monitor
 //
 //  Created by Nico Verbruggen on 29/11/2021.
 //  Copyright © 2022 Nico Verbruggen. All rights reserved.
diff --git a/tests/unit/Testables/Filesystem/TestableFileSystemTest.swift b/tests/unit/Testables/Filesystem/TestableFileSystemTest.swift
new file mode 100644
index 0000000..1329933
--- /dev/null
+++ b/tests/unit/Testables/Filesystem/TestableFileSystemTest.swift
@@ -0,0 +1,61 @@
+//
+//  TestableFileSystemTest.swift
+//  PHP Monitor
+//
+//  Created by Nico Verbruggen on 01/11/2022.
+//  Copyright © 2022 Nico Verbruggen. All rights reserved.
+//
+
+import XCTest
+
+class TestableFileSystemTest: XCTestCase {
+
+    override class func setUp() {
+        ActiveFileSystem.useTestable([
+            "/home/user/bin": .fake(.directory),
+            "/home/user/bin/foo": .fake(.binary),
+            "/home/user/documents": .fake(.directory),
+            "/home/user/docs": .fake(.symlink, "/home/user/documents"),
+            "/home/user/documents/nice.txt": .fake(.text, "69"),
+            "/home/user/documents/script.sh": .fake(.text, "echo 'cool';")
+        ])
+    }
+
+    func test_testable_fs_is_in_use() {
+        XCTAssertTrue(FileSystem is TestableFileSystem)
+    }
+
+    func test_binary_directory_exists() {
+        XCTAssertTrue(FileSystem.directoryExists("/home/user/bin"))
+    }
+
+    func test_binary_directory_is_writable() {
+        XCTAssertTrue(FileSystem.isWriteableFile("/home/user/bin"))
+    }
+
+    func test_binary_exists() {
+        XCTAssertTrue(FileSystem.isExecutableFile("/home/user/bin/foo"))
+    }
+
+    func test_can_write_text_to_executable() throws {
+        try! FileSystem.writeAtomicallyToFile("/home/user/bin/bar", content: "bar bar bar!")
+
+        XCTAssertFalse(FileSystem.isExecutableFile("/home/user/bin/bar"))
+
+        try! FileSystem.makeExecutable("/home/user/bin/bar")
+
+        XCTAssertTrue(FileSystem.isExecutableFile("/home/user/bin/bar"))
+    }
+
+    func test_can_create_directory() throws {
+        try! FileSystem.createDirectory(
+            "/home/nico/phpmon/config",
+            withIntermediateDirectories: true
+        )
+
+        XCTAssertTrue(FileSystem.anyExists("/home/nico/phpmon/config"))
+        XCTAssertTrue(FileSystem.directoryExists("/home/nico/phpmon/config"))
+    }
+
+    // TODO: Implement and test the remove() and move() methods and reorganize method order
+}
diff --git a/tests/unit/Testables/Shell/SystemShellTest.swift b/tests/unit/Testables/Shell/SystemShellTest.swift
index 7771285..467fc9a 100644
--- a/tests/unit/Testables/Shell/SystemShellTest.swift
+++ b/tests/unit/Testables/Shell/SystemShellTest.swift
@@ -1,6 +1,6 @@
 //
 //  SystemShellTest.swift
-//  phpmon-tests
+//  PHP Monitor
 //
 //  Created by Nico Verbruggen on 28/09/2022.
 //  Copyright © 2022 Nico Verbruggen. All rights reserved.
diff --git a/tests/unit/Testables/Shell/FakeShellTest.swift b/tests/unit/Testables/Shell/TestableShellTest.swift
similarity index 92%
rename from tests/unit/Testables/Shell/FakeShellTest.swift
rename to tests/unit/Testables/Shell/TestableShellTest.swift
index 16cfc34..d2a819a 100644
--- a/tests/unit/Testables/Shell/FakeShellTest.swift
+++ b/tests/unit/Testables/Shell/TestableShellTest.swift
@@ -1,6 +1,6 @@
 //
-//  ShellTest.swift
-//  phpmon-tests
+//  TestableShellTest.swift
+//  PHP Monitor
 //
 //  Created by Nico Verbruggen on 20/09/2022.
 //  Copyright © 2022 Nico Verbruggen. All rights reserved.
@@ -8,7 +8,7 @@
 
 import XCTest
 
-class FakeShellTest: XCTestCase {
+class TestableShellTest: XCTestCase {
     func test_fake_shell_output_can_be_declared() async {
         let greeting = BatchFakeShellOutput(items: [
             .instant("Hello world\n"),
diff --git a/tests/unit/Versions/AppUpdaterCheckTest.swift b/tests/unit/Versions/AppUpdaterCheckTest.swift
index 11215fd..c70d5a2 100644
--- a/tests/unit/Versions/AppUpdaterCheckTest.swift
+++ b/tests/unit/Versions/AppUpdaterCheckTest.swift
@@ -1,6 +1,6 @@
 //
 //  AppUpdaterCheckTest.swift
-//  phpmon-tests
+//  PHP Monitor
 //
 //  Created by Nico Verbruggen on 10/05/2022.
 //  Copyright © 2022 Nico Verbruggen. All rights reserved.
diff --git a/tests/unit/Versions/PhpVersionDetectionTest.swift b/tests/unit/Versions/PhpVersionDetectionTest.swift
index 64541b0..d9f636e 100644
--- a/tests/unit/Versions/PhpVersionDetectionTest.swift
+++ b/tests/unit/Versions/PhpVersionDetectionTest.swift
@@ -1,6 +1,6 @@
 //
 //  PhpVersionDetectionTest.swift
-//  phpmon-tests
+//  PHP Monitor
 //
 //  Created by Nico Verbruggen on 01/04/2021.
 //  Copyright © 2022 Nico Verbruggen. All rights reserved.
diff --git a/tests/unit/Versions/ValetVersionExtractorTest.swift b/tests/unit/Versions/ValetVersionExtractorTest.swift
index e1499f3..9e7673e 100644
--- a/tests/unit/Versions/ValetVersionExtractorTest.swift
+++ b/tests/unit/Versions/ValetVersionExtractorTest.swift
@@ -1,6 +1,6 @@
 //
 //  ValetTest.swift
-//  phpmon-tests
+//  PHP Monitor
 //
 //  Created by Nico Verbruggen on 29/11/2021.
 //  Copyright © 2022 Nico Verbruggen. All rights reserved.
diff --git a/tests/unit/Versions/VersionExtractorTest.swift b/tests/unit/Versions/VersionExtractorTest.swift
index 3501af1..6b44657 100644
--- a/tests/unit/Versions/VersionExtractorTest.swift
+++ b/tests/unit/Versions/VersionExtractorTest.swift
@@ -1,6 +1,6 @@
 //
 //  VersionExtractorTest.swift
-//  phpmon-tests
+//  PHP Monitor
 //
 //  Created by Nico Verbruggen on 16/12/2021.
 //  Copyright © 2022 Nico Verbruggen. All rights reserved.