[Sessions] Add NetworkInfo abstraction over CoreTelephony helpers (#10399)

Author: samedson

FirebaseSessions/Sources/ApplicationInfo.swift

@@ -38,8 +38,11 @@ protocol ApplicationInfoProtocol {
 class ApplicationInfo: ApplicationInfoProtocol {
   let appID: String
 
-  init(appID: String) {
+  private let networkInfo: NetworkInfoProtocol
+
+  init(appID: String, networkInfo: NetworkInfoProtocol = NetworkInfo()) {
     self.appID = appID
+    self.networkInfo = networkInfo
   }
 
   var bundleID: String {
@@ -58,6 +61,6 @@ class ApplicationInfo: ApplicationInfoProtocol {
   }
 
   var mccMNC: String {
-    return FIRSESGetMccMnc() ?? ""
+    return FIRSESValidateMccMnc(networkInfo.mobileCountryCode, networkInfo.mobileNetworkCode) ?? ""
   }
 }

FirebaseSessions/Sources/NanoPB/FIRSESNanoPBHelpers.h

@@ -65,8 +65,14 @@ BOOL FIRSESIsPBStringEqual(pb_bytes_array_t* _Nullable pbString, NSString* _Null
 /// @param data NSData that's expected
 BOOL FIRSESIsPBDataEqual(pb_bytes_array_t* _Nullable pbArray, NSData* _Nullable data);
 
+/// Returns the cellular mobile country code (mnc) if CoreTelephony is supported, otherwise nil
+NSString* _Nullable FIRSESNetworkMobileCountryCode(void);
+
+/// Returns the cellular mobile network code (mnc) if CoreTelephony is supported, otherwise nil
+NSString* _Nullable FIRSESNetworkMobileNetworkCode(void);
+
 /// Returns the validated MccMnc if it is available, or nil if the device does not support telephone
-NSString* _Nullable FIRSESGetMccMnc(void);
+NSString* _Nullable FIRSESValidateMccMnc(NSString* _Nullable mcc, NSString* _Nullable mnc);
 
 NS_ASSUME_NONNULL_END
 

FirebaseSessions/Sources/NanoPB/FIRSESNanoPBHelpers.m

@@ -135,28 +135,49 @@ BOOL FIRSESIsPBDataEqual(pb_bytes_array_t *_Nullable pbArray, NSData *_Nullable
   });
   return networkInfo;
 }
+#endif
+
+NSString *_Nullable FIRSESNetworkMobileCountryCode(void) {
+#ifdef TARGET_HAS_MOBILE_CONNECTIVITY
+  CTTelephonyNetworkInfo *networkInfo = FIRSESNetworkInfo();
+  CTCarrier *provider = networkInfo.subscriberCellularProvider;
+  return provider.mobileCountryCode;
+#endif
+  return nil;
+}
 
-NSString *FIRSESValidatedMccMnc(NSString *mcc, NSString *mnc) {
-  if ([mcc length] != 3 || [mnc length] < 2 || [mnc length] > 3) return nil;
+NSString *_Nullable FIRSESNetworkMobileNetworkCode(void) {
+#ifdef TARGET_HAS_MOBILE_CONNECTIVITY
+  CTTelephonyNetworkInfo *networkInfo = FIRSESNetworkInfo();
+  CTCarrier *provider = networkInfo.subscriberCellularProvider;
+  return provider.mobileNetworkCode;
+#endif
+  return nil;
+}
 
+NSString *_Nullable FIRSESValidateMccMnc(NSString *_Nullable mcc, NSString *_Nullable mnc) {
+  // These are both nil if the target does not support mobile connectivity
+  if (mcc == nil && mnc == nil) {
+    return nil;
+  }
+
+  if (mcc.length != 3 || mnc.length < 2 || mnc.length > 3) {
+    return nil;
+  }
+
+  // If the resulting appended mcc + mnc contains characters that are not
+  // decimal digits, return nil
   static NSCharacterSet *notDigits;
   static dispatch_once_t token;
   dispatch_once(&token, ^{
     notDigits = [[NSCharacterSet decimalDigitCharacterSet] invertedSet];
   });
   NSString *mccMnc = [mcc stringByAppendingString:mnc];
-  if ([mccMnc rangeOfCharacterFromSet:notDigits].location != NSNotFound) return nil;
-  return mccMnc;
-}
-#endif
+  if ([mccMnc rangeOfCharacterFromSet:notDigits].location != NSNotFound) {
+    return nil;
+  }
 
-NSString *_Nullable FIRSESGetMccMnc(void) {
-#ifdef TARGET_HAS_MOBILE_CONNECTIVITY
-  CTTelephonyNetworkInfo *networkInfo = FIRSESNetworkInfo();
-  CTCarrier *provider = networkInfo.subscriberCellularProvider;
-  return FIRSESValidatedMccMnc(provider.mobileCountryCode, provider.mobileNetworkCode);
-#endif
-  return nil;
+  return mccMnc;
 }
 
 NS_ASSUME_NONNULL_END

FirebaseSessions/Sources/NetworkInfo.swift

@@ -0,0 +1,31 @@
+//
+// Copyright 2022 Google LLC
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//      http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+import Foundation
+protocol NetworkInfoProtocol {
+  var mobileCountryCode: String? { get }
+
+  var mobileNetworkCode: String? { get }
+}
+
+class NetworkInfo: NetworkInfoProtocol {
+  var mobileCountryCode: String? {
+    return FIRSESNetworkMobileCountryCode()
+  }
+
+  var mobileNetworkCode: String? {
+    return FIRSESNetworkMobileNetworkCode()
+  }
+}

FirebaseSessions/Tests/Unit/ApplicationInfoTests.swift

@@ -0,0 +1,65 @@
+//
+// Copyright 2022 Google LLC
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//      http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+import XCTest
+
+@testable import FirebaseSessions
+
+class ApplicationInfoTests: XCTestCase {
+  var appInfo: ApplicationInfo!
+  var mockNetworkInfo: MockNetworkInfo!
+
+  override func setUp() {
+    super.setUp()
+    mockNetworkInfo = MockNetworkInfo()
+    appInfo = ApplicationInfo(appID: "testAppID", networkInfo: mockNetworkInfo)
+  }
+
+  func test_mccMNC_validatesCorrectly() {
+    let expectations: [(mobileCountryCode: String, mobileNetworkCode: String, expected: String)] = [
+      ("310", "004", "310004"),
+      ("310", "01", "31001"),
+      ("001", "50", "00150"),
+    ]
+
+    expectations
+      .forEach { (mobileCountryCode: String, mobileNetworkCode: String, expected: String) in
+        mockNetworkInfo.mobileCountryCode = mobileCountryCode
+        mockNetworkInfo.mobileNetworkCode = mobileNetworkCode
+
+        XCTAssertEqual(appInfo.mccMNC, expected)
+      }
+  }
+
+  func test_mccMNC_isEmptyWhenInvalid() {
+    let expectations: [(mobileCountryCode: String?, mobileNetworkCode: String?)] = [
+      ("3100", "004"), // MCC too long
+      ("31", "01"), // MCC too short
+      ("310", "0512"), // MNC too long
+      ("L00", "003"), // MCC contains non-decimal characters
+      ("300", "00T"), // MNC contains non-decimal characters
+      (nil, nil), // Handle nils gracefully
+      (nil, "001"),
+      ("310", nil),
+    ]
+
+    expectations.forEach { (mobileCountryCode: String?, mobileNetworkCode: String?) in
+      mockNetworkInfo.mobileCountryCode = mobileCountryCode
+      mockNetworkInfo.mobileNetworkCode = mobileNetworkCode
+
+      XCTAssertEqual(appInfo.mccMNC, "")
+    }
+  }
+}

FirebaseSessions/Tests/Unit/Mocks/MockNetworkInfo.swift

@@ -0,0 +1,23 @@
+//
+// Copyright 2022 Google LLC
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//      http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+import Foundation
+
+@testable import FirebaseSessions
+
+class MockNetworkInfo: NetworkInfoProtocol {
+  var mobileCountryCode: String?
+  var mobileNetworkCode: String?
+}