Proof-of-concept: pretty print URLRequest body when JSON (#157)

* Pretty print json bodies in URLRequests.

* wip

* Update URLRequest.swift

* Update URLRequest.swift

* Update URLRequest.swift

* Update URLRequest.swift

* backward compatible api.

* fix compile error and use inline snapshot

Author: mbrandonw

Sources/SnapshotTesting/Snapshotting/URLRequest.swift

@@ -2,19 +2,39 @@ import Foundation
 
 extension Snapshotting where Value == URLRequest, Format == String {
   /// A snapshot strategy for comparing requests based on raw equality.
-  public static let raw = SimplySnapshotting.lines.pullback { (request: URLRequest) in
+  public static let raw = Snapshotting.raw(pretty: false)
 
-    let method = "\(request.httpMethod ?? "GET") \(request.url?.absoluteString ?? "(null)")"
+  /// A snapshot strategy for comparing requests based on raw equality.
+  ///
+  /// - Parameter pretty: Attempts to pretty print the body of the request (supports JSON).
+  public static func raw(pretty: Bool) -> Snapshotting {
+    return SimplySnapshotting.lines.pullback { (request: URLRequest) in
+      let method = "\(request.httpMethod ?? "GET") \(request.url?.absoluteString ?? "(null)")"
 
-    let headers = (request.allHTTPHeaderFields ?? [:])
-      .map { key, value in "\(key): \(value)" }
-      .sorted()
+      let headers = (request.allHTTPHeaderFields ?? [:])
+        .map { key, value in "\(key): \(value)" }
+        .sorted()
 
-    let body = request.httpBody
-      .map { ["\n\(String(decoding: $0, as: UTF8.self))"] }
-      ?? []
+      let body: [String]
+      do {
+        if pretty, #available(iOS 11.0, macOS 10.13, tvOS 11.0, *) {
+          body = try request.httpBody
+            .map { try JSONSerialization.jsonObject(with: $0, options: []) }
+            .map { try JSONSerialization.data(withJSONObject: $0, options: [.prettyPrinted, .sortedKeys]) }
+            .map { ["\n\(String(decoding: $0, as: UTF8.self))"] }
+            ?? []
+        } else {
+          throw NSError(domain: "co.pointfree.Never", code: 1, userInfo: nil)
+        }
+      }
+      catch {
+        body = request.httpBody
+          .map { ["\n\(String(decoding: $0, as: UTF8.self))"] }
+          ?? []
+      }
 
-    return ([method] + headers + body).joined(separator: "\n")
+      return ([method] + headers + body).joined(separator: "\n")
+    }
   }
 
   /// A snapshot strategy for comparing requests based on a cURL representation.

Tests/SnapshotTestingTests/SnapshotTestingTests.swift

@@ -606,6 +606,26 @@ final class SnapshotTestingTests: XCTestCase {
     head.addValue("pf_session={}", forHTTPHeaderField: "Cookie")
     assertSnapshot(matching: head, as: .raw, named: "head")
     assertSnapshot(matching: head, as: .curl, named: "head-curl")
+
+    post = URLRequest(url: URL(string: "https://www.pointfree.co/subscribe")!)
+    post.httpMethod = "POST"
+    post.addValue("pf_session={\"user_id\":\"0\"}", forHTTPHeaderField: "Cookie")
+    post.addValue("application/json", forHTTPHeaderField: "Accept")
+    post.httpBody = Data("""
+                         {"pricing": {"lane": "individual","billing": "monthly"}}
+                         """.utf8)
+    _assertInlineSnapshot(matching: post, as: .raw(pretty: true), with: """
+    POST https://www.pointfree.co/subscribe
+    Accept: application/json
+    Cookie: pf_session={"user_id":"0"}
+    
+    {
+      "pricing" : {
+        "billing" : "monthly",
+        "lane" : "individual"
+      }
+    }
+    """)
   }
 
   func testWebView() throws {

Tests/SnapshotTestingTests/__Snapshots__/SnapshotTestingTests/testURLRequest.post-json.txt

@@ -0,0 +1,10 @@
+POST https://www.pointfree.co/subscribe
+Accept: application/json
+Cookie: pf_session={"user_id":"0"}
+
+{
+  "pricing" : {
+    "billing" : "monthly",
+    "lane" : "individual"
+  }
+}