Add coverage for ignoring unchanged files

Sources/Config/ConfigGenerator.swift

@@ -10,6 +10,8 @@ import Foundation
 
 public class ConfigGenerator {
 
+    var printer: Printing = Printer()
+
     public init() {}
 
     public func run(_ arguments: [String]) throws {
@@ -44,15 +46,15 @@ public class ConfigGenerator {
                 if newData == currentData {
                     shouldWrite = false
                 } else {
-                    print("Existing file different from new file, writing \(url.lastPathComponent)\nExisting: \(currentData), New: \(newData)")
+                    printer.print(message: "Existing file different from new file, writing \(url.lastPathComponent)\nExisting: \(currentData), New: \(newData)")
                 }
             } else {
-                print("Existing file not present, writing \(url.lastPathComponent)")
+                printer.print(message: "Existing file not present, writing \(url.lastPathComponent)")
             }
             if shouldWrite == false {
-                print("Ignoring \(url.lastPathComponent) as it has not changed")
+                printer.print(message: "Ignoring \(url.lastPathComponent) as it has not changed")
             } else {
-                print("Wrote \(url.lastPathComponent)")
+                printer.print(message: "Wrote \(url.lastPathComponent)")
                 try configurationFile.description.write(to: swiftOutput, atomically: true, encoding: .utf8)
             }
         }
@@ -62,3 +64,13 @@ public class ConfigGenerator {
         return Arguments.Option.all.compactMap { $0.usage }.joined(separator: "\n")
     }
 }
+
+protocol Printing {
+    func print(message: String)
+}
+
+struct Printer: Printing {
+    func print(message: String) {
+        Swift.print(message)
+    }
+}

Tests/ConfigTests/ConfigGeneratorTests.swift

@@ -41,7 +41,7 @@ class ConfigGeneratorTests: XCTestCase {
         let generator = ConfigGenerator()
         try generator.run(validOptions())
         try configFixtures.forEach {
-            let contents = try String(contentsOf: tempURL.appendingPathComponent(filenames[$0.key] ?? $0.key).appendingPathExtension("ext.swift"), encoding: .utf8)
+            let contents = try String(contentsOf: url(for: $0.key), encoding: .utf8)
             expect(contents).to(equal(expectedStrings[$0.key]))
         }
     }
@@ -61,6 +61,52 @@ class ConfigGeneratorTests: XCTestCase {
         }
     }
 
+    func testItDoesNotWriteIfTheConfigHasNotChanged() throws {
+        let generator = ConfigGenerator()
+        let mockPrinter = MockPrinter()
+        generator.printer = mockPrinter
+        try givenAConfigFile((key: "standard", value: generatorConfiguration))
+        try generator.run(validOptions())
+        let outputURL = url(for: "standard")
+        let inputURL = configURL(for: "standard")
+        let currentTouchDate = try FileManager.default.attributesOfItem(atPath: outputURL.path)[.modificationDate] as? Date
+        expect(mockPrinter.receivedMessages.first).to(equal("Existing file not present, writing \(inputURL.lastPathComponent)"))
+        expect(mockPrinter.receivedMessages.last).to(equal("Wrote \(inputURL.lastPathComponent)"))
+        mockPrinter.reset()
+        try generator.run(validOptions())
+        let newTouchDate = try FileManager.default.attributesOfItem(atPath: outputURL.path)[.modificationDate] as? Date
+        expect(currentTouchDate).to(equal(newTouchDate))
+        expect(mockPrinter.receivedMessages.first).to(equal("Ignoring \(inputURL.lastPathComponent) as it has not changed"))
+    }
+
+    func testItDoesWriteIfTheConfigHasChanged() throws {
+        let generator = ConfigGenerator()
+        let outputURL = url(for: "standard")
+        let inputURL = configURL(for: "standard")
+
+        try givenAConfigFile((key: "standard", value: generatorConfiguration))
+        try generator.run(validOptions())
+        let currentTouchDate = try FileManager.default.attributesOfItem(atPath: outputURL.path)[.modificationDate] as? Date
+
+        let mockPrinter = MockPrinter()
+        generator.printer = mockPrinter
+
+        try givenAConfigFile((key: "standard", value: enumConfiguration))
+        try generator.run(validOptions())
+        let newTouchDate = try FileManager.default.attributesOfItem(atPath: outputURL.path)[.modificationDate] as? Date
+        expect(currentTouchDate).to(beLessThan(newTouchDate))
+        expect(mockPrinter.receivedMessages.first).to(equal("Existing file different from new file, writing \(inputURL.lastPathComponent)\nExisting: \(expectedStrings["standard"]!), New: \(expectedStrings["enumconfig"]!.replacingOccurrences(of: "enumconfig", with: "standard"))"))
+    }
+
+    func testItCanPrintItsUsage() {
+        let generator = ConfigGenerator()
+        expect(generator.usage).to(equal("""
+        \(Arguments.Option.scheme.usage)
+        \(Arguments.Option.configPath.usage)
+        \(Arguments.Option.additionalExtension.usage)
+        """))
+    }
+
     func validOptions() -> [String] {
         return [
             "",
@@ -70,16 +116,28 @@ class ConfigGeneratorTests: XCTestCase {
         ]
     }
 
+    func givenAConfigFile(_ config: (key: String, value: [String: Any])) throws {
+        try write(object: config.value, toConfigFileNamed: config.key)
+    }
+
     func givenSomeConfigFiles() throws {
         try configFixtures.forEach {
-            try write(object: $0.value, toConfigFileNamed: $0.key)
+            try givenAConfigFile($0)
         }
     }
 
     func write(object: Any, toConfigFileNamed name: String) throws {
         let data = try JSONSerialization.data(withJSONObject: object, options: [])
         try data.write(to: tempURL.appendingPathComponent(name).appendingPathExtension("config"))
     }
+
+    private func url(for key: String) -> URL {
+        return tempURL.appendingPathComponent(filenames[key] ?? key).appendingPathExtension("ext.swift")
+    }
+
+    private func configURL(for key: String) -> URL {
+        return tempURL.appendingPathComponent(filenames[key] ?? key).appendingPathExtension("config")
+    }
 }
 
 private let configFixtures = [
@@ -147,3 +205,15 @@ private let extensionConfiguration: [String: Any] = [
         "extensionOn": "UIColor"
     ]
 ]
+
+private class MockPrinter: Printing {
+    var receivedMessages = [String]()
+
+    func print(message: String) {
+        receivedMessages.append(message)
+    }
+
+    func reset() {
+        receivedMessages.removeAll()
+    }
+}