Refactor CreateAPITests structure and snapshotting (CreateAPI#128)

* Introduce new Snapshotter class as an entry point for running shapshot tests

* Remove test support outside of CreateAPITests target

* Update AllPackages to support new dir structure

* Move Helpers.swift into ./Helpers as TemporaryDirectory.swift

* Move SpecFixture type into its own file

Author: liamnichols

Package.swift

@@ -41,9 +41,7 @@ let package = Package(
         .testTarget(
             name: "create-api-tests",
             dependencies: ["create-api"],
-            path: "Tests/CreateAPITests",
-            exclude: ["AllPackages"],
-            resources: [.copy("Expected"), .copy("Specs")]
+            path: "Tests/CreateAPITests"
         ),
         .testTarget(
             name: "CreateOptionsTests",

Scripts/test-generated.sh

@@ -2,5 +2,5 @@
 
 set -e
 
-cd ./Tests/CreateAPITests/AllPackages
+cd ./Tests/Support/AllPackages
 swift build

Tests/CreateAPITests/GenerateTestCase.swift

@@ -1,26 +1,9 @@
 import XCTest
 @testable import create_api
 
-class GenerateTestCase: XCTestCase {
-    struct SpecFixture {
-        let name: String
-        let ext: String
-
-        static let cookpad = SpecFixture(name: "cookpad", ext: "json")
-        static let discriminator = SpecFixture(name: "discriminator", ext: "yaml")
-        static let edgecases = SpecFixture(name: "edgecases", ext: "yaml")
-        static let github = SpecFixture(name: "github", ext: "yaml")
-        static let inlining = SpecFixture(name: "inlining", ext: "yaml")
-        static let petstore = SpecFixture(name: "petstore", ext: "yaml")
-        static let stripParentNameNestedObjects = SpecFixture(name: "strip-parent-name-nested-objects", ext: "yaml")
-        static let testQueryParameters = SpecFixture(name: "test-query-parameters", ext: "yaml")
-
-        var path: String {
-            pathForSpec(named: name, ext: ext)
-        }
-    }
-    
+class GenerateTestCase: XCTestCase {   
     var temp: TemporaryDirectory!
+    let snapshotter: Snapshotter = .shared
 
     override func setUp() {
         super.setUp()
@@ -40,13 +23,12 @@ class GenerateTestCase: XCTestCase {
         arguments: [String] = [],
         configuration: String? = nil
     ) throws {
-        let output = temp.url
+        let outputURL = temp.url
             .appendingPathComponent("Output")
-            .path
 
         // Append the output, config and spec to the arguments passed
         var arguments = arguments
-        arguments.append(contentsOf: ["--output", output])
+        arguments.append(contentsOf: ["--output", outputURL.path])
         if let configuration = configuration {
             arguments.append(contentsOf: ["--config", self.config(configuration, ext: "yml")])
         }
@@ -56,7 +38,7 @@ class GenerateTestCase: XCTestCase {
         try generate(arguments)
 
         // Then the output should match what was generated
-        try compare(expected: name, actual: output)
+        try snapshotter.processSnapshot(at: outputURL, against: name)
     }
 
     func generate(_ arguments: [String]) throws {

Tests/CreateAPITests/Helpers/SpecFixture.swift

@@ -0,0 +1,28 @@
+import Foundation
+
+struct SpecFixture {
+    let name: String
+    let ext: String
+
+    static let cookpad = SpecFixture(name: "cookpad", ext: "json")
+    static let discriminator = SpecFixture(name: "discriminator", ext: "yaml")
+    static let edgecases = SpecFixture(name: "edgecases", ext: "yaml")
+    static let github = SpecFixture(name: "github", ext: "yaml")
+    static let inlining = SpecFixture(name: "inlining", ext: "yaml")
+    static let petstore = SpecFixture(name: "petstore", ext: "yaml")
+    static let stripParentNameNestedObjects = SpecFixture(name: "strip-parent-name-nested-objects", ext: "yaml")
+    static let testQueryParameters = SpecFixture(name: "test-query-parameters", ext: "yaml")
+
+    var path: String {
+        URL(fileURLWithPath: #filePath)
+            .appendingPathComponent("..")
+            .appendingPathComponent("..")
+            .appendingPathComponent("..")
+            .appendingPathComponent("Support")
+            .appendingPathComponent("Specs")
+            .appendingPathComponent(name)
+            .appendingPathExtension(ext)
+            .resolvingSymlinksInPath()
+            .path
+    }
+}

Tests/CreateAPITests/Helpers.swift renamed to Tests/CreateAPITests/Helpers/TemporaryDirectory.swift

@@ -1,17 +1,4 @@
-import XCTest
-
-func file(named name: String, ext: String) -> Data {
-    let url = Bundle.module.url(forResource: name, withExtension: ext)
-    return try! Data(contentsOf: url!)
-}
-
-func fileExists(named name: String, ext: String) -> Bool {
-    Bundle.module.url(forResource: name, withExtension: ext) != nil
-}
-
-func pathForSpec(named name: String, ext: String) -> String {
-    Bundle.module.url(forResource: name, withExtension: ext, subdirectory: "Specs")!.path
-}
+import Foundation
 
 struct TemporaryDirectory {
     let url: URL

Tests/CreateAPITests/Snapshotting/DirectoryDiffer.swift

@@ -0,0 +1,8 @@
+import Foundation
+
+struct DirectoryDiffer {
+    func compare(_ expectedURL: URL, against actualURL: URL) throws {
+        // TODO: Rewrite differ and leverage https://github.com/pointfreeco/swift-custom-dump?
+        try diff(expectedURL: expectedURL, actualURL: actualURL)
+    }
+}

Tests/CreateAPITests/Snapshots.swift renamed to Tests/CreateAPITests/Snapshotting/LegacyDiffer.swift

@@ -1,27 +1,8 @@
 import XCTest
 
-private let generateSnapshots = false
 private let openDiff = false
 
-func compare(expected: String, actual: String) throws {
-    let expectedURL = Bundle.module.resourceURL!
-        .appendingPathComponent("Expected")
-        .appendingPathComponent(expected)
-    let actualURL = URL(fileURLWithPath: actual)
-    
-    if generateSnapshots || !FileManager.default.fileExists(atPath: expectedURL.path) {
-        let destinationURL = URL(fileURLWithPath: #filePath)
-            .deletingLastPathComponent()
-            .appendingPathComponent("Expected")
-            .appendingPathComponent(actualURL.lastPathComponent)
-        try? FileManager.default.removeItem(at: destinationURL)
-        try FileManager.default.copyItem(at: actualURL, to: destinationURL)
-    } else {
-        try diff(expectedURL: expectedURL, actualURL: actualURL)
-    }
-}
-
-private func diff(expectedURL: URL, actualURL: URL) throws {
+func diff(expectedURL: URL, actualURL: URL) throws {
     func contents(at url: URL) throws -> [URL] {
         try FileManager.default.contentsOfDirectory(at: url, includingPropertiesForKeys: [.isDirectoryKey], options: [.skipsHiddenFiles])
     }

Tests/CreateAPITests/Snapshotting/Snapshotter.swift

@@ -0,0 +1,75 @@
+import Foundation
+
+private let generateSnapshots = false
+
+class Snapshotter {
+    enum Behavior {
+        case assert, record
+    }
+
+    static let shared = Snapshotter(behavior: generateSnapshots ? .record : .assert)
+
+    let behavior: Behavior
+    private(set) var recordedSnapshots: [URL]
+    private let fileManager: FileManager
+
+    private init(behavior: Behavior) {
+        self.behavior = behavior
+        self.recordedSnapshots = []
+        self.fileManager = .default
+    }
+
+    /// Processes a snapshot at the given path by either asserting a match against a stored snapshot, or rewriting it.
+    func processSnapshot(at generatedURL: URL, against name: String) throws {
+        let snapshotURL = snapshotLocation(for: name)
+
+        switch behavior {
+        case .assert:
+            try DirectoryDiffer().compare(snapshotURL, against: generatedURL)
+
+        case .record:
+            try resetAllSnapshotsIfNeeded()
+            try resetDirectory(at: snapshotURL, create: false)
+            try fileManager.copyItem(at: generatedURL, to: snapshotURL)
+            recordedSnapshots.append(snapshotURL)
+        }
+    }
+
+    /// The location of a generated snapshot stored on disk
+    private func snapshotLocation(for name: String) -> URL {
+        snapshotDirectory.appendingPathComponent(name)
+    }
+
+    /// Deletes the contents of the snapshot directory if it was already there in preparation to re-record all outputs
+    private func resetAllSnapshotsIfNeeded() throws {
+        guard shouldResetAllSnapshots else { return }
+        try resetDirectory(at: snapshotDirectory)
+    }
+
+    private var shouldResetAllSnapshots: Bool {
+        guard recordedSnapshots.isEmpty else { return false }
+        return true // TODO: Don't reset snapshot directory when only running a subset of tests
+    }
+
+    /// The URL to the snapshot storage directory
+    var snapshotDirectory: URL {
+        URL(fileURLWithPath: #filePath)
+            .appendingPathComponent("..")
+            .appendingPathComponent("..")
+            .appendingPathComponent("..")
+            .appendingPathComponent("Support")
+            .appendingPathComponent("Snapshots")
+            .resolvingSymlinksInPath()
+    }
+
+    /// Deletes and recreates the directory at the given location.
+    private func resetDirectory(at url: URL, create: Bool = true) throws {
+        if fileManager.fileExists(atPath: url.path) {
+            try fileManager.removeItem(at: url)
+        }
+
+        if create {
+            try fileManager.createDirectory(at: url, withIntermediateDirectories: true)
+        }
+    }
+}

Tests/CreateAPITests/AllPackages/Package.resolved renamed to Tests/Support/AllPackages/Package.resolved

@@ -15,44 +15,44 @@ let package = Package(
         .library(name: "AllPackages", targets: ["AllPackages"])
     ],
     dependencies: [
-        .package(path: "../Expected/cookpad"),
-        .package(path: "../Expected/discriminator"),
-        .package(path: "../Expected/edgecases-change-access-control"),
-        .package(path: "../Expected/edgecases-coding-keys"),
-        .package(path: "../Expected/edgecases-default"),
-        .package(path: "../Expected/edgecases-disable-acronyms"),
-        .package(path: "../Expected/edgecases-disable-enums"),
-        .package(path: "../Expected/edgecases-indent-with-two-width-spaces"),
-        .package(path: "../Expected/edgecases-int32-int64"),
-        .package(path: "../Expected/edgecases-rename"),
-        .package(path: "../Expected/edgecases-rename-properties"),
-        .package(path: "../Expected/edgecases-tabs"),
-        .package(path: "../Expected/edgecases-yaml-config"),
-        .package(path: "../Expected/inlining-default"),
-        .package(path: "../Expected/OctoKit"),
-        .package(path: "../Expected/petstore-base-class"),
-        .package(path: "../Expected/petstore-change-entityname"),
-        .package(path: "../Expected/petstore-change-namespace-when-operations-style"),
-        .package(path: "../Expected/petstore-change-namespace-when-rest-style"),
-        .package(path: "../Expected/petstore-custom-imports"),
-        .package(path: "../Expected/petstore-default"),
-        .package(path: "../Expected/petstore-disable-comments"),
-        .package(path: "../Expected/petstore-disable-init-with-coder"),
-        .package(path: "../Expected/petstore-disable-inlining"),
-        .package(path: "../Expected/petstore-disable-mutable-properties"),
-        .package(path: "../Expected/petstore-enable-mutable-properties"),
-        .package(path: "../Expected/petstore-entity-exclude"),
-        .package(path: "../Expected/petstore-filename-template"),
-        .package(path: "../Expected/petstore-generate-classes"),
-        .package(path: "../Expected/petstore-identifiable"),
-        .package(path: "../Expected/petstore-only-schemas"),
-        .package(path: "../Expected/petstore-single-threaded"),
-        .package(path: "../Expected/petstore-some-entities-as-classes"),
-        .package(path: "../Expected/petstore-some-entities-as-structs"),
-        .package(path: "../Expected/petstore-merge-sources"),
-        .package(path: "../Expected/strip-parent-name-nested-objects-default"),
-        .package(path: "../Expected/strip-parent-name-nested-objects-enabled"),
-        .package(path: "../Expected/test-query-parameters")
+        .package(path: "../Snapshots/cookpad"),
+        .package(path: "../Snapshots/discriminator"),
+        .package(path: "../Snapshots/edgecases-change-access-control"),
+        .package(path: "../Snapshots/edgecases-coding-keys"),
+        .package(path: "../Snapshots/edgecases-default"),
+        .package(path: "../Snapshots/edgecases-disable-acronyms"),
+        .package(path: "../Snapshots/edgecases-disable-enums"),
+        .package(path: "../Snapshots/edgecases-indent-with-two-width-spaces"),
+        .package(path: "../Snapshots/edgecases-int32-int64"),
+        .package(path: "../Snapshots/edgecases-rename"),
+        .package(path: "../Snapshots/edgecases-rename-properties"),
+        .package(path: "../Snapshots/edgecases-tabs"),
+        .package(path: "../Snapshots/edgecases-yaml-config"),
+        .package(path: "../Snapshots/inlining-default"),
+        .package(path: "../Snapshots/OctoKit"),
+        .package(path: "../Snapshots/petstore-base-class"),
+        .package(path: "../Snapshots/petstore-change-entityname"),
+        .package(path: "../Snapshots/petstore-change-namespace-when-operations-style"),
+        .package(path: "../Snapshots/petstore-change-namespace-when-rest-style"),
+        .package(path: "../Snapshots/petstore-custom-imports"),
+        .package(path: "../Snapshots/petstore-default"),
+        .package(path: "../Snapshots/petstore-disable-comments"),
+        .package(path: "../Snapshots/petstore-disable-init-with-coder"),
+        .package(path: "../Snapshots/petstore-disable-inlining"),
+        .package(path: "../Snapshots/petstore-disable-mutable-properties"),
+        .package(path: "../Snapshots/petstore-enable-mutable-properties"),
+        .package(path: "../Snapshots/petstore-entity-exclude"),
+        .package(path: "../Snapshots/petstore-filename-template"),
+        .package(path: "../Snapshots/petstore-generate-classes"),
+        .package(path: "../Snapshots/petstore-identifiable"),
+        .package(path: "../Snapshots/petstore-only-schemas"),
+        .package(path: "../Snapshots/petstore-single-threaded"),
+        .package(path: "../Snapshots/petstore-some-entities-as-classes"),
+        .package(path: "../Snapshots/petstore-some-entities-as-structs"),
+        .package(path: "../Snapshots/petstore-merge-sources"),
+        .package(path: "../Snapshots/strip-parent-name-nested-objects-default"),
+        .package(path: "../Snapshots/strip-parent-name-nested-objects-enabled"),
+        .package(path: "../Snapshots/test-query-parameters")
     ],
     targets: [
         .target(