diff --git a/GoogleSignIn/Tests/Unit/GIDEMMSupportTest.m b/GoogleSignIn/Tests/Unit/GIDEMMSupportTest.m
new file mode 100644
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+++ b/GoogleSignIn/Tests/Unit/GIDEMMSupportTest.m
@@ -0,0 +1,229 @@
+/*
+ * 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 <TargetConditionals.h>
+
+#if TARGET_OS_IOS && !TARGET_OS_MACCATALYST
+
+#import <XCTest/XCTest.h>
+
+#import "GoogleSignIn/Sources/GIDEMMSupport.h"
+
+#import "GoogleSignIn/Sources/Public/GoogleSignIn/GIDSignIn.h"
+
+#import "GoogleSignIn/Sources/GIDEMMErrorHandler.h"
+#import "GoogleSignIn/Sources/GIDMDMPasscodeState.h"
+
+#ifdef SWIFT_PACKAGE
+@import AppAuth;
+@import GoogleUtilities_MethodSwizzler;
+@import GoogleUtilities_SwizzlerTestHelpers;
+@import OCMock;
+#else
+#import <GoogleUtilities/GULSwizzler.h>
+#import <GoogleUtilities/GULSwizzler+Unswizzle.h>
+#import <AppAuth/OIDError.h>
+#import <OCMock/OCMock.h>
+#endif
+
+NS_ASSUME_NONNULL_BEGIN
+
+// The system name in old iOS versions.
+static NSString *const kOldIOSName = @"iPhone OS";
+
+// The system name in new iOS versions.
+static NSString *const kNewIOSName = @"iOS";
+
+// They keys in EMM dictionary.
+static NSString *const kEMMKey = @"emm_support";
+static NSString *const kDeviceOSKey = @"device_os";
+static NSString *const kEMMPasscodeInfoKey = @"emm_passcode_info";
+
+@interface GIDEMMSupportTest : XCTestCase
+@end
+
+@implementation GIDEMMSupportTest
+
+- (void)testUpdatedEMMParametersWithParameters_NoEMMKey {
+  NSDictionary *originalParameters = @{
+    @"not_emm_support_key" : @"xyz",
+  };
+
+  NSDictionary *updatedEMMParameters =
+      [GIDEMMSupport updatedEMMParametersWithParameters:originalParameters];
+
+  XCTAssertEqualObjects(updatedEMMParameters, originalParameters);
+}
+
+- (void)testUpdateEMMParametersWithParameters_systemName {
+  [GULSwizzler swizzleClass:[UIDevice class]
+                   selector:@selector(systemName)
+            isClassSelector:NO
+                  withBlock:^(id sender) { return kNewIOSName; }];
+
+  NSDictionary *originalParameters = @{
+    kEMMKey : @"xyz",
+  };
+
+  NSDictionary *updatedEMMParameters =
+      [GIDEMMSupport updatedEMMParametersWithParameters:originalParameters];
+
+  NSDictionary *expectedParameters = @{
+    kEMMKey : @"xyz",
+    kDeviceOSKey : [NSString stringWithFormat:@"%@ %@", kNewIOSName, [self systemVersion]]
+  };
+
+  XCTAssertEqualObjects(updatedEMMParameters, expectedParameters);
+
+  [self addTeardownBlock:^{
+    [GULSwizzler unswizzleClass:[UIDevice class]
+                       selector:@selector(systemName)
+                isClassSelector:NO];
+  }];
+}
+
+// When the systemName is @"iPhone OS" we still get "iOS".
+- (void)testUpdateEMMParametersWithParameters_systemNameNormalization {
+  [GULSwizzler swizzleClass:[UIDevice class]
+                    selector:@selector(systemName)
+             isClassSelector:NO
+                   withBlock:^(id sender) { return kOldIOSName; }];
+
+  NSDictionary *originalParameters = @{
+    kEMMKey : @"xyz",
+  };
+
+  NSDictionary *updatedEMMParameters =
+      [GIDEMMSupport updatedEMMParametersWithParameters:originalParameters];
+
+  NSDictionary *expectedParameters = @{
+    kEMMKey : @"xyz",
+    kDeviceOSKey : [NSString stringWithFormat:@"%@ %@", kNewIOSName, [self systemVersion]]
+  };
+
+  XCTAssertEqualObjects(updatedEMMParameters, expectedParameters);
+
+  [self addTeardownBlock:^{
+    [GULSwizzler unswizzleClass:[UIDevice class]
+                       selector:@selector(systemName)
+                isClassSelector:NO];
+  }];
+}
+
+- (void)testUpdateEMMParametersWithParameters_passcodInfo {
+  [GULSwizzler swizzleClass:[UIDevice class]
+                   selector:@selector(systemName)
+            isClassSelector:NO
+                  withBlock:^(id sender) { return kOldIOSName; }];
+
+  NSDictionary *originalParameters = @{
+    kEMMKey : @"xyz",
+    kDeviceOSKey : @"old one",
+    kEMMPasscodeInfoKey : @"something",
+  };
+
+  NSDictionary *updatedEMMParameters =
+      [GIDEMMSupport updatedEMMParametersWithParameters:originalParameters];
+
+  NSDictionary *expectedParameters = @{
+    kEMMKey : @"xyz",
+    kDeviceOSKey : [NSString stringWithFormat:@"%@ %@", kNewIOSName, [self systemVersion]],
+    kEMMPasscodeInfoKey : [GIDMDMPasscodeState passcodeState].info,
+  };
+
+  XCTAssertEqualObjects(updatedEMMParameters, expectedParameters);
+
+  [self addTeardownBlock:^{
+    [GULSwizzler unswizzleClass:[UIDevice class]
+                       selector:@selector(systemName)
+                isClassSelector:NO];
+  }];
+  
+}
+
+- (void)testHandleTokenFetchEMMError_errorIsEMM {
+  // Set expectations.
+  NSDictionary *errorJSON = @{ @"error" : @"EMM Specific Error" };
+  NSError *emmError = [NSError errorWithDomain:@"anydomain"
+                                          code:12345
+                                      userInfo:@{ OIDOAuthErrorResponseErrorKey : errorJSON }];
+  id mockEMMErrorHandler = OCMStrictClassMock([GIDEMMErrorHandler class]);
+  [[[mockEMMErrorHandler stub] andReturn:mockEMMErrorHandler] sharedInstance];
+  __block void (^savedCompletion)(void);
+  [[[mockEMMErrorHandler stub] andReturnValue:@YES]
+      handleErrorFromResponse:errorJSON completion:[OCMArg checkWithBlock:^(id arg) {
+    savedCompletion = arg;
+    return YES;
+  }]];
+
+  XCTestExpectation *notCalled = [self expectationWithDescription:@"Callback is not called"];
+  notCalled.inverted = YES;
+  XCTestExpectation *called = [self expectationWithDescription:@"Callback is called"];
+
+  [GIDEMMSupport handleTokenFetchEMMError:emmError completion:^(NSError *error) {
+    [notCalled fulfill];
+    [called fulfill];
+    XCTAssertEqualObjects(error.domain, kGIDSignInErrorDomain);
+    XCTAssertEqual(error.code, kGIDSignInErrorCodeEMM);
+  }];
+  
+  [self waitForExpectations:@[ notCalled ] timeout:1];
+  savedCompletion();
+  [self waitForExpectations:@[ called ] timeout:1];
+}
+
+- (void)testHandleTokenFetchEMMError_errorIsNotEMM {
+  // Set expectations.
+  NSDictionary *errorJSON = @{ @"error" : @"Not EMM Specific Error" };
+  NSError *emmError = [NSError errorWithDomain:@"anydomain"
+                                          code:12345
+                                      userInfo:@{ OIDOAuthErrorResponseErrorKey : errorJSON }];
+  id mockEMMErrorHandler = OCMStrictClassMock([GIDEMMErrorHandler class]);
+  [[[mockEMMErrorHandler stub] andReturn:mockEMMErrorHandler] sharedInstance];
+  __block void (^savedCompletion)(void);
+  [[[mockEMMErrorHandler stub] andReturnValue:@NO]
+      handleErrorFromResponse:errorJSON completion:[OCMArg checkWithBlock:^(id arg) {
+    savedCompletion = arg;
+    return YES;
+  }]];
+
+  XCTestExpectation *notCalled = [self expectationWithDescription:@"Callback is not called"];
+  notCalled.inverted = YES;
+  XCTestExpectation *called = [self expectationWithDescription:@"Callback is called"];
+  
+  [GIDEMMSupport handleTokenFetchEMMError:emmError completion:^(NSError *error) {
+    [notCalled fulfill];
+    [called fulfill];
+    XCTAssertEqualObjects(error.domain, @"anydomain");
+    XCTAssertEqual(error.code, 12345);
+  }];
+
+  [self waitForExpectations:@[ notCalled ] timeout:1];
+  savedCompletion();
+  [self waitForExpectations:@[ called ] timeout:1];
+}
+
+# pragma mark - Helpers
+
+- (NSString *)systemVersion {
+  return [UIDevice currentDevice].systemVersion;
+}
+
+@end
+
+NS_ASSUME_NONNULL_END
+
+#endif // TARGET_OS_IOS && !TARGET_OS_MACCATALYST