diff --git a/Signal.xcodeproj/project.pbxproj b/Signal.xcodeproj/project.pbxproj
index be57dca33..4da01d946 100644
--- a/Signal.xcodeproj/project.pbxproj
+++ b/Signal.xcodeproj/project.pbxproj
@@ -154,6 +154,7 @@
 		3478506C1FD9B78A007B8332 /* NoopNotificationsManager.swift in Sources */ = {isa = PBXBuildFile; fileRef = 347850681FD9B78A007B8332 /* NoopNotificationsManager.swift */; };
 		347850711FDAEB17007B8332 /* OWSUserProfile.m in Sources */ = {isa = PBXBuildFile; fileRef = 3478506F1FDAEB16007B8332 /* OWSUserProfile.m */; };
 		347850721FDAEB17007B8332 /* OWSUserProfile.h in Headers */ = {isa = PBXBuildFile; fileRef = 347850701FDAEB16007B8332 /* OWSUserProfile.h */; settings = {ATTRIBUTES = (Public, ); }; };
+		34843B2421432293004DED45 /* SignalBaseTest.m in Sources */ = {isa = PBXBuildFile; fileRef = 34843B2221432292004DED45 /* SignalBaseTest.m */; };
 		348570A820F67575004FF32B /* OWSMessageHeaderView.m in Sources */ = {isa = PBXBuildFile; fileRef = 348570A620F67574004FF32B /* OWSMessageHeaderView.m */; };
 		348BB25D20A0C5530047AEC2 /* ContactShareViewHelper.swift in Sources */ = {isa = PBXBuildFile; fileRef = 348BB25C20A0C5530047AEC2 /* ContactShareViewHelper.swift */; };
 		3491D9A121022DB7001EF5A1 /* CDSSigningCertificateTest.m in Sources */ = {isa = PBXBuildFile; fileRef = 3491D9A021022DB7001EF5A1 /* CDSSigningCertificateTest.m */; };
@@ -790,6 +791,8 @@
 		347850681FD9B78A007B8332 /* NoopNotificationsManager.swift */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.swift; path = NoopNotificationsManager.swift; sourceTree = "<group>"; };
 		3478506F1FDAEB16007B8332 /* OWSUserProfile.m */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.c.objc; path = OWSUserProfile.m; sourceTree = "<group>"; };
 		347850701FDAEB16007B8332 /* OWSUserProfile.h */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.c.h; path = OWSUserProfile.h; sourceTree = "<group>"; };
+		34843B2221432292004DED45 /* SignalBaseTest.m */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.c.objc; path = SignalBaseTest.m; sourceTree = "<group>"; };
+		34843B2321432293004DED45 /* SignalBaseTest.h */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.c.h; path = SignalBaseTest.h; sourceTree = "<group>"; };
 		348570A620F67574004FF32B /* OWSMessageHeaderView.m */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.c.objc; path = OWSMessageHeaderView.m; sourceTree = "<group>"; };
 		348570A720F67574004FF32B /* OWSMessageHeaderView.h */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.c.h; path = OWSMessageHeaderView.h; sourceTree = "<group>"; };
 		348BB25C20A0C5530047AEC2 /* ContactShareViewHelper.swift */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.swift; path = ContactShareViewHelper.swift; sourceTree = "<group>"; };
@@ -2306,6 +2309,8 @@
 		B660F66C1C29867F00687D6E /* test */ = {
 			isa = PBXGroup;
 			children = (
+				34843B2321432293004DED45 /* SignalBaseTest.h */,
+				34843B2221432292004DED45 /* SignalBaseTest.m */,
 				4C3EF8002109184A0007EBF7 /* SSKTests */,
 				34C6B0A41FA0E46F00D35993 /* Assets */,
 				B660F6731C29867F00687D6E /* call */,
@@ -3480,6 +3485,7 @@
 				4C3EF7FD2107DDEE0007EBF7 /* ParamParserTest.swift in Sources */,
 				B660F6DB1C29868000687D6E /* FunctionalUtilTest.m in Sources */,
 				45E7A6A81E71CA7E00D44FB5 /* DisplayableTextFilterTest.swift in Sources */,
+				34843B2421432293004DED45 /* SignalBaseTest.m in Sources */,
 				4C3EF802210918740007EBF7 /* SSKProtoEnvelopeTest.swift in Sources */,
 				452D1AF12081059C00A67F7F /* StringAdditionsTest.swift in Sources */,
 				4C4BC6C32102D697004040C9 /* ContactDiscoveryOperationTest.swift in Sources */,
diff --git a/Signal/test/Models/AccountManagerTest.swift b/Signal/test/Models/AccountManagerTest.swift
index 62378e0c7..67590f6fb 100644
--- a/Signal/test/Models/AccountManagerTest.swift
+++ b/Signal/test/Models/AccountManagerTest.swift
@@ -56,7 +56,7 @@ class VerifyingTSAccountManager: FailingTSAccountManager {
 class TokenObtainingTSAccountManager: VerifyingTSAccountManager {
 }
 
-class AccountManagerTest: XCTestCase {
+class AccountManagerTest: SignalBaseTest {
 
     let tsAccountManager = FailingTSAccountManager(networkManager: TSNetworkManager.shared(), primaryStorage: OWSPrimaryStorage.shared())
     var preferences = OWSPreferences()
@@ -103,7 +103,7 @@ class AccountManagerTest: XCTestCase {
     }
 
     func testSuccessfulRegistration() {
-        Environment.clearCurrentForTests()
+        Environment.clearSharedForTests()
         Environment.setCurrent(Release.releaseEnvironment())
 
         let tsAccountManager = TokenObtainingTSAccountManager(networkManager: TSNetworkManager.shared(), primaryStorage: OWSPrimaryStorage.shared())
diff --git a/Signal/test/Models/OWSDeviceProvisioningURLParserTest.m b/Signal/test/Models/OWSDeviceProvisioningURLParserTest.m
index 8af07e92a..bfeb0c8ed 100644
--- a/Signal/test/Models/OWSDeviceProvisioningURLParserTest.m
+++ b/Signal/test/Models/OWSDeviceProvisioningURLParserTest.m
@@ -3,10 +3,10 @@
 //
 
 #import "OWSDeviceProvisioningURLParser.h"
+#import "SignalBaseTest.h"
 #import <SignalServiceKit/NSData+OWS.h>
-#import <XCTest/XCTest.h>
 
-@interface OWSDeviceProvisioningURLParserTest : XCTestCase
+@interface OWSDeviceProvisioningURLParserTest : SignalBaseTest
 
 @end
 
diff --git a/Signal/test/SSKTests/ParamParserTest.swift b/Signal/test/SSKTests/ParamParserTest.swift
index d4f9f506b..49c92769f 100644
--- a/Signal/test/SSKTests/ParamParserTest.swift
+++ b/Signal/test/SSKTests/ParamParserTest.swift
@@ -4,7 +4,7 @@
 
 import XCTest
 
-class ParamParserTest: XCTestCase {
+class ParamParserTest: SignalBaseTest {
 
     override func setUp() {
         super.setUp()
diff --git a/Signal/test/SSKTests/SSKProtoEnvelopeTest.swift b/Signal/test/SSKTests/SSKProtoEnvelopeTest.swift
index 58206520a..d1cddfb8b 100644
--- a/Signal/test/SSKTests/SSKProtoEnvelopeTest.swift
+++ b/Signal/test/SSKTests/SSKProtoEnvelopeTest.swift
@@ -7,7 +7,7 @@ import XCTest
 import SignalServiceKit
 import SwiftProtobuf
 
-class SSKProtoEnvelopeTest: XCTestCase {
+class SSKProtoEnvelopeTest: SignalBaseTest {
 
     override func setUp() {
         super.setUp()
diff --git a/Signal/test/SignalBaseTest.h b/Signal/test/SignalBaseTest.h
new file mode 100644
index 000000000..6d96e72f1
--- /dev/null
+++ b/Signal/test/SignalBaseTest.h
@@ -0,0 +1,13 @@
+//
+//  Copyright (c) 2018 Open Whisper Systems. All rights reserved.
+//
+
+#import <XCTest/XCTest.h>
+
+NS_ASSUME_NONNULL_BEGIN
+
+@interface SignalBaseTest : XCTestCase
+
+@end
+
+NS_ASSUME_NONNULL_END
diff --git a/Signal/test/SignalBaseTest.m b/Signal/test/SignalBaseTest.m
new file mode 100644
index 000000000..1364d132e
--- /dev/null
+++ b/Signal/test/SignalBaseTest.m
@@ -0,0 +1,36 @@
+//
+//  Copyright (c) 2018 Open Whisper Systems. All rights reserved.
+//
+
+#import "SignalBaseTest.h"
+#import "Environment.h"
+#import <SignalServiceKit/OWSPrimaryStorage.h>
+#import <SignalServiceKit/TestAppContext.h>
+
+NS_ASSUME_NONNULL_BEGIN
+
+@implementation SignalBaseTest
+
+- (void)setUp
+{
+    NSLog(@"%@ setUp", self.logTag);
+
+    [super setUp];
+
+    ClearCurrentAppContextForTests();
+
+    SetCurrentAppContext([TestAppContext new]);
+}
+
+- (void)tearDown
+{
+    NSLog(@"%@ tearDown", self.logTag);
+
+    ClearCurrentAppContextForTests();
+
+    [super tearDown];
+}
+
+@end
+
+NS_ASSUME_NONNULL_END
diff --git a/Signal/test/ViewControllers/ConversationViewItemTest.m b/Signal/test/ViewControllers/ConversationViewItemTest.m
index 710cb23ec..f2f7419d3 100644
--- a/Signal/test/ViewControllers/ConversationViewItemTest.m
+++ b/Signal/test/ViewControllers/ConversationViewItemTest.m
@@ -3,16 +3,16 @@
 //
 
 #import "ConversationViewItem.h"
+#import "SignalBaseTest.h"
 #import <MobileCoreServices/MobileCoreServices.h>
 #import <SignalMessaging/SignalMessaging-Swift.h>
 #import <SignalServiceKit/MIMETypeUtil.h>
 #import <SignalServiceKit/TSAttachmentStream.h>
 #import <SignalServiceKit/TSContactThread.h>
 #import <SignalServiceKit/TSOutgoingMessage.h>
-#import <XCTest/XCTest.h>
 #import <YapDatabase/YapDatabaseConnection.h>
 
-@interface ConversationViewItemTest : XCTestCase
+@interface ConversationViewItemTest : SignalBaseTest
 
 @property TSThread *thread;
 @property ConversationStyle *conversationStyle;
diff --git a/Signal/test/call/PeerConnectionClientTest.swift b/Signal/test/call/PeerConnectionClientTest.swift
index 09fee6e17..61aa400b3 100644
--- a/Signal/test/call/PeerConnectionClientTest.swift
+++ b/Signal/test/call/PeerConnectionClientTest.swift
@@ -46,7 +46,7 @@ class FakePeerConnectionClientDelegate: PeerConnectionClientDelegate {
     }
 }
 
-class PeerConnectionClientTest: XCTestCase {
+class PeerConnectionClientTest: SignalBaseTest {
 
     var client: PeerConnectionClient!
     var clientDelegate: FakePeerConnectionClientDelegate!
diff --git a/Signal/test/contact/ContactDiscoveryOperationTest.swift b/Signal/test/contact/ContactDiscoveryOperationTest.swift
index 75c76b5c2..6289dfbc1 100644
--- a/Signal/test/contact/ContactDiscoveryOperationTest.swift
+++ b/Signal/test/contact/ContactDiscoveryOperationTest.swift
@@ -5,7 +5,7 @@
 import XCTest
 @testable import SignalServiceKit
 
-class ContactDiscoveryOperationTest: XCTestCase {
+class ContactDiscoveryOperationTest: SignalBaseTest {
 
     override func setUp() {
         super.setUp()
diff --git a/Signal/test/contact/ContactsPickerTest.swift b/Signal/test/contact/ContactsPickerTest.swift
index c5279a0b2..bf98b4750 100644
--- a/Signal/test/contact/ContactsPickerTest.swift
+++ b/Signal/test/contact/ContactsPickerTest.swift
@@ -6,7 +6,7 @@ import XCTest
 import Contacts
 @testable import Signal
 
-final class ContactsPickerTest: XCTestCase {
+final class ContactsPickerTest: SignalBaseTest {
     private var prevLang: Any?
 
     override func setUp() {
diff --git a/Signal/test/contact/OWSContactsManagerTest.m b/Signal/test/contact/OWSContactsManagerTest.m
index 133720803..cdf3235c1 100644
--- a/Signal/test/contact/OWSContactsManagerTest.m
+++ b/Signal/test/contact/OWSContactsManagerTest.m
@@ -1,12 +1,12 @@
 //
-//  Copyright (c) 2017 Open Whisper Systems. All rights reserved.
+//  Copyright (c) 2018 Open Whisper Systems. All rights reserved.
 //
 
+#import "SignalBaseTest.h"
 #import "TestUtil.h"
 #import <SignalMessaging/OWSContactsManager.h>
-#import <XCTest/XCTest.h>
 
-@interface OWSContactsManagerTest : XCTestCase
+@interface OWSContactsManagerTest : SignalBaseTest
 
 @end
 
diff --git a/Signal/test/push/PushManagerTest.m b/Signal/test/push/PushManagerTest.m
index dba45114c..9c2f534ef 100644
--- a/Signal/test/push/PushManagerTest.m
+++ b/Signal/test/push/PushManagerTest.m
@@ -1,14 +1,10 @@
 //
-//  PushManagerTest.m
-//  Signal
-//
-//  Created by Frederic Jacobs on 12/09/14.
-//  Copyright (c) 2014 Open Whisper Systems. All rights reserved.
+//  Copyright (c) 2018 Open Whisper Systems. All rights reserved.
 //
 
-#import <XCTest/XCTest.h>
+#import "SignalBaseTest.h"
 
-@interface PushManagerTest : XCTestCase
+@interface PushManagerTest : SignalBaseTest
 
 @end
 
diff --git a/Signal/test/util/ByteParserTest.swift b/Signal/test/util/ByteParserTest.swift
index c70644c65..dac0b9136 100644
--- a/Signal/test/util/ByteParserTest.swift
+++ b/Signal/test/util/ByteParserTest.swift
@@ -5,7 +5,7 @@
 import XCTest
 @testable import Signal
 
-class ByteParserTest: XCTestCase {
+class ByteParserTest: SignalBaseTest {
 
     override func setUp() {
         super.setUp()
diff --git a/Signal/test/util/CDSSigningCertificateTest.m b/Signal/test/util/CDSSigningCertificateTest.m
index 25825c2d1..83a171b4b 100644
--- a/Signal/test/util/CDSSigningCertificateTest.m
+++ b/Signal/test/util/CDSSigningCertificateTest.m
@@ -2,11 +2,11 @@
 //  Copyright (c) 2018 Open Whisper Systems. All rights reserved.
 //
 
+#import "SignalBaseTest.h"
 #import <SignalServiceKit/CDSSigningCertificate.h>
 #import <SignalServiceKit/NSData+OWS.h>
-#import <XCTest/XCTest.h>
 
-@interface CDSSigningCertificateTest : XCTestCase
+@interface CDSSigningCertificateTest : SignalBaseTest
 
 @end
 
diff --git a/Signal/test/util/DisplayableTextFilterTest.swift b/Signal/test/util/DisplayableTextFilterTest.swift
index e1dbb40d6..204f4521e 100644
--- a/Signal/test/util/DisplayableTextFilterTest.swift
+++ b/Signal/test/util/DisplayableTextFilterTest.swift
@@ -6,7 +6,7 @@ import XCTest
 @testable import Signal
 @testable import SignalMessaging
 
-class DisplayableTextTest: XCTestCase {
+class DisplayableTextTest: SignalBaseTest {
 
     override func setUp() {
         super.setUp()
diff --git a/Signal/test/util/ExceptionsTest.h b/Signal/test/util/ExceptionsTest.h
index 7b1e4c581..1ee996e49 100644
--- a/Signal/test/util/ExceptionsTest.h
+++ b/Signal/test/util/ExceptionsTest.h
@@ -1,5 +1,9 @@
-#import <XCTest/XCTest.h>
+//
+//  Copyright (c) 2018 Open Whisper Systems. All rights reserved.
+//
 
-@interface ExceptionsTest : XCTestCase
+#import "SignalBaseTest.h"
+
+@interface ExceptionsTest : SignalBaseTest
 
 @end
diff --git a/Signal/test/util/FunctionalUtilTest.h b/Signal/test/util/FunctionalUtilTest.h
index 29fe5f829..95736e0c8 100644
--- a/Signal/test/util/FunctionalUtilTest.h
+++ b/Signal/test/util/FunctionalUtilTest.h
@@ -1,5 +1,9 @@
-#import <XCTest/XCTest.h>
+//
+//  Copyright (c) 2018 Open Whisper Systems. All rights reserved.
+//
 
-@interface FunctionalUtilTest : XCTestCase
+#import "SignalBaseTest.h"
+
+@interface FunctionalUtilTest : SignalBaseTest
 
 @end
diff --git a/Signal/test/util/ImageCacheTest.swift b/Signal/test/util/ImageCacheTest.swift
index 8b495e21f..d943275ed 100644
--- a/Signal/test/util/ImageCacheTest.swift
+++ b/Signal/test/util/ImageCacheTest.swift
@@ -1,11 +1,11 @@
 //
-//  Copyright (c) 2017 Open Whisper Systems. All rights reserved.
+//  Copyright (c) 2018 Open Whisper Systems. All rights reserved.
 //
 
 import XCTest
 @testable import Signal
 
-class ImageCacheTest: XCTestCase {
+class ImageCacheTest: SignalBaseTest {
 
     var imageCache: ImageCache!
 
@@ -19,9 +19,9 @@ class ImageCacheTest: XCTestCase {
     override func setUp() {
         super.setUp()
          self.imageCache = ImageCache()
-        imageCache.setImage(firstVariation, forKey:cacheKey1, diameter:100)
-        imageCache.setImage(secondVariation, forKey:cacheKey1, diameter:200)
-        imageCache.setImage(otherImage, forKey:cacheKey2, diameter:100)
+        imageCache.setImage(firstVariation, forKey: cacheKey1, diameter: 100)
+        imageCache.setImage(secondVariation, forKey: cacheKey1, diameter: 200)
+        imageCache.setImage(otherImage, forKey: cacheKey2, diameter: 100)
     }
 
     override func tearDown() {
@@ -30,32 +30,32 @@ class ImageCacheTest: XCTestCase {
     }
 
     func testSetGet() {
-        XCTAssertEqual(firstVariation, imageCache.image(forKey:cacheKey1, diameter: 100))
-        XCTAssertEqual(secondVariation, imageCache.image(forKey:cacheKey1, diameter: 200))
-        XCTAssertNotEqual(secondVariation, imageCache.image(forKey:cacheKey1, diameter: 100))
-        XCTAssertEqual(otherImage, imageCache.image(forKey:cacheKey2, diameter: 100))
-        XCTAssertNil(imageCache.image(forKey:cacheKey2, diameter: 200))
+        XCTAssertEqual(firstVariation, imageCache.image(forKey: cacheKey1, diameter: 100))
+        XCTAssertEqual(secondVariation, imageCache.image(forKey: cacheKey1, diameter: 200))
+        XCTAssertNotEqual(secondVariation, imageCache.image(forKey: cacheKey1, diameter: 100))
+        XCTAssertEqual(otherImage, imageCache.image(forKey: cacheKey2, diameter: 100))
+        XCTAssertNil(imageCache.image(forKey: cacheKey2, diameter: 200))
     }
 
     func testRemoveAllForKey() {
         // sanity check
-        XCTAssertEqual(firstVariation, imageCache.image(forKey:cacheKey1, diameter: 100))
-        XCTAssertEqual(otherImage, imageCache.image(forKey:cacheKey2, diameter: 100))
+        XCTAssertEqual(firstVariation, imageCache.image(forKey: cacheKey1, diameter: 100))
+        XCTAssertEqual(otherImage, imageCache.image(forKey: cacheKey2, diameter: 100))
 
-        imageCache.removeAllImages(forKey:cacheKey1)
+        imageCache.removeAllImages(forKey: cacheKey1)
 
-        XCTAssertNil(imageCache.image(forKey:cacheKey1, diameter: 100))
-        XCTAssertNil(imageCache.image(forKey:cacheKey1, diameter: 200))
-        XCTAssertEqual(otherImage, imageCache.image(forKey:cacheKey2, diameter: 100))
+        XCTAssertNil(imageCache.image(forKey: cacheKey1, diameter: 100))
+        XCTAssertNil(imageCache.image(forKey: cacheKey1, diameter: 200))
+        XCTAssertEqual(otherImage, imageCache.image(forKey: cacheKey2, diameter: 100))
     }
 
     func testRemoveAll() {
-        XCTAssertEqual(firstVariation, imageCache.image(forKey:cacheKey1, diameter: 100))
+        XCTAssertEqual(firstVariation, imageCache.image(forKey: cacheKey1, diameter: 100))
 
         imageCache.removeAllImages()
 
-        XCTAssertNil(imageCache.image(forKey:cacheKey1, diameter: 100))
-        XCTAssertNil(imageCache.image(forKey:cacheKey1, diameter: 200))
-        XCTAssertNil(imageCache.image(forKey:cacheKey2, diameter: 100))
+        XCTAssertNil(imageCache.image(forKey: cacheKey1, diameter: 100))
+        XCTAssertNil(imageCache.image(forKey: cacheKey1, diameter: 200))
+        XCTAssertNil(imageCache.image(forKey: cacheKey2, diameter: 100))
     }
 }
diff --git a/Signal/test/util/OWSDatabaseConverterTest.h b/Signal/test/util/OWSDatabaseConverterTest.h
index f83de9fd0..de2c82a74 100644
--- a/Signal/test/util/OWSDatabaseConverterTest.h
+++ b/Signal/test/util/OWSDatabaseConverterTest.h
@@ -2,11 +2,11 @@
 //  Copyright (c) 2018 Open Whisper Systems. All rights reserved.
 //
 
-#import <XCTest/XCTest.h>
+#import "SignalBaseTest.h"
 
 NS_ASSUME_NONNULL_BEGIN
 
-@interface OWSDatabaseConverterTest : XCTestCase
+@interface OWSDatabaseConverterTest : SignalBaseTest
 
 @end
 
diff --git a/Signal/test/util/OWSScrubbingLogFormatterTest.m b/Signal/test/util/OWSScrubbingLogFormatterTest.m
index 6aa0bf4fb..16ac6eb1a 100644
--- a/Signal/test/util/OWSScrubbingLogFormatterTest.m
+++ b/Signal/test/util/OWSScrubbingLogFormatterTest.m
@@ -3,11 +3,11 @@
 //
 
 #import "OWSScrubbingLogFormatter.h"
-#import <XCTest/XCTest.h>
+#import "SignalBaseTest.h"
 
 NS_ASSUME_NONNULL_BEGIN
 
-@interface OWSScrubbingLogFormatterTest : XCTestCase
+@interface OWSScrubbingLogFormatterTest : SignalBaseTest
 
 @property (nonatomic) NSDate *testDate;
 
diff --git a/Signal/test/util/ProtoParsingTest.m b/Signal/test/util/ProtoParsingTest.m
index 91432e28f..c0f4e3624 100644
--- a/Signal/test/util/ProtoParsingTest.m
+++ b/Signal/test/util/ProtoParsingTest.m
@@ -2,6 +2,7 @@
 //  Copyright (c) 2018 Open Whisper Systems. All rights reserved.
 //
 
+#import "SignalBaseTest.h"
 #import <Curve25519Kit/Randomness.h>
 #import <SignalServiceKit/ContactsManagerProtocol.h>
 #import <SignalServiceKit/NSData+OWS.h>
@@ -9,7 +10,6 @@
 #import <SignalServiceKit/OWSGroupsOutputStream.h>
 #import <SignalServiceKit/SignalAccount.h>
 #import <SignalServiceKit/SignalServiceKit-Swift.h>
-#import <XCTest/XCTest.h>
 
 NS_ASSUME_NONNULL_BEGIN
 
@@ -91,7 +91,7 @@ NS_ASSUME_NONNULL_BEGIN
 
 #pragma mark -
 
-@interface ProtoParsingTest : XCTestCase
+@interface ProtoParsingTest : SignalBaseTest
 
 @end
 
diff --git a/Signal/test/util/SearcherTest.swift b/Signal/test/util/SearcherTest.swift
index 4538aaa63..31b8ff513 100644
--- a/Signal/test/util/SearcherTest.swift
+++ b/Signal/test/util/SearcherTest.swift
@@ -88,7 +88,7 @@ class FakeContactsManager: NSObject, ContactsManagerProtocol {
 let bobRecipientId = "+49030183000"
 let aliceRecipientId = "+12345678900"
 
-class ConversationSearcherTest: XCTestCase {
+class ConversationSearcherTest: SignalBaseTest {
 
     // MARK: - Dependencies
     var searcher: ConversationSearcher {
@@ -381,7 +381,7 @@ class ConversationSearcherTest: XCTestCase {
     }
 }
 
-class SearcherTest: XCTestCase {
+class SearcherTest: SignalBaseTest {
 
     struct TestCharacter {
         let name: String
diff --git a/Signal/test/util/StringAdditionsTest.swift b/Signal/test/util/StringAdditionsTest.swift
index f0c785f94..005d742c5 100644
--- a/Signal/test/util/StringAdditionsTest.swift
+++ b/Signal/test/util/StringAdditionsTest.swift
@@ -4,7 +4,7 @@
 
 import XCTest
 
-class StringAdditionsTest: XCTestCase {
+class StringAdditionsTest: SignalBaseTest {
 
     override func setUp() {
         super.setUp()
diff --git a/Signal/test/util/UtilTest.h b/Signal/test/util/UtilTest.h
index 3252acaa8..97e23ad65 100644
--- a/Signal/test/util/UtilTest.h
+++ b/Signal/test/util/UtilTest.h
@@ -1,5 +1,9 @@
-#import <XCTest/XCTest.h>
+//
+//  Copyright (c) 2018 Open Whisper Systems. All rights reserved.
+//
 
-@interface UtilTest : XCTestCase
+#import "SignalBaseTest.h"
+
+@interface UtilTest : SignalBaseTest
 
 @end
diff --git a/SignalMessaging/environment/Environment.h b/SignalMessaging/environment/Environment.h
index 71042899c..fe4d7754b 100644
--- a/SignalMessaging/environment/Environment.h
+++ b/SignalMessaging/environment/Environment.h
@@ -37,6 +37,6 @@
 @property (class, nonatomic) Environment *shared;
 
 // Should only be called by tests.
-+ (void)clearCurrentForTests;
++ (void)clearSharedForTests;
 
 @end
diff --git a/SignalMessaging/environment/Environment.m b/SignalMessaging/environment/Environment.m
index 103fce4a3..7a3957bee 100644
--- a/SignalMessaging/environment/Environment.m
+++ b/SignalMessaging/environment/Environment.m
@@ -49,7 +49,7 @@ static Environment *sharedEnvironment = nil;
     sharedEnvironment = environment;
 }
 
-+ (void)clearCurrentForTests
++ (void)clearSharedForTests
 {
     sharedEnvironment = nil;
 }
diff --git a/SignalServiceKit/tests/Account/SignedPreKeyDeletionTests.m b/SignalServiceKit/tests/Account/SignedPreKeyDeletionTests.m
index ff3611aba..f60062412 100644
--- a/SignalServiceKit/tests/Account/SignedPreKeyDeletionTests.m
+++ b/SignalServiceKit/tests/Account/SignedPreKeyDeletionTests.m
@@ -3,9 +3,9 @@
 //
 
 #import "OWSPrimaryStorage+SignedPreKeyStore.h"
+#import "SSKBaseTest.h"
 #import "TSPreKeyManager.h"
 #import <AxolotlKit/SignedPrekeyRecord.h>
-#import <XCTest/XCTest.h>
 
 @interface  TSPreKeyManager (Testing)
 
@@ -13,7 +13,7 @@
 
 @end
 
-@interface SignedPreKeyDeletionTests : XCTestCase
+@interface SignedPreKeyDeletionTests : SSKBaseTest
 
 @end
 
diff --git a/SignalServiceKit/tests/Account/TSAttributesTest.m b/SignalServiceKit/tests/Account/TSAttributesTest.m
index 92389b8ec..1204a0aa3 100644
--- a/SignalServiceKit/tests/Account/TSAttributesTest.m
+++ b/SignalServiceKit/tests/Account/TSAttributesTest.m
@@ -3,10 +3,11 @@
 //
 
 #import "TSAttributes.h"
+#import "SSKBaseTest.h"
 #import "TSAccountManager.h"
 #import <XCTest/XCTest.h>
 
-@interface TSAttributesTest : XCTestCase
+@interface TSAttributesTest : SSKBaseTest
 
 @end
 
diff --git a/SignalServiceKit/tests/Contacts/ContactSortingTest.m b/SignalServiceKit/tests/Contacts/ContactSortingTest.m
index 855a02662..940af935e 100644
--- a/SignalServiceKit/tests/Contacts/ContactSortingTest.m
+++ b/SignalServiceKit/tests/Contacts/ContactSortingTest.m
@@ -3,13 +3,15 @@
 //
 
 #import "Contact.h"
-#import <XCTest/XCTest.h>
+#import "SSKBaseTest.h"
+
+@import Contacts;
 
 @import Contacts;
 
 NS_ASSUME_NONNULL_BEGIN
 
-@interface ContactSortingTest : XCTestCase
+@interface ContactSortingTest : SSKBaseTest
 
 @end
 
diff --git a/SignalServiceKit/tests/Contacts/OWSDisappearingMessagesConfigurationTest.m b/SignalServiceKit/tests/Contacts/OWSDisappearingMessagesConfigurationTest.m
index 3ce466ef9..1f8703502 100644
--- a/SignalServiceKit/tests/Contacts/OWSDisappearingMessagesConfigurationTest.m
+++ b/SignalServiceKit/tests/Contacts/OWSDisappearingMessagesConfigurationTest.m
@@ -1,12 +1,13 @@
-//  Created by Michael Kirk on 9/25/16.
-//  Copyright © 2016 Open Whisper Systems. All rights reserved.
+//
+//  Copyright (c) 2018 Open Whisper Systems. All rights reserved.
+//
 
 #import "OWSDisappearingMessagesConfiguration.h"
-#import <XCTest/XCTest.h>
+#import "SSKBaseTest.h"
 
 NS_ASSUME_NONNULL_BEGIN
 
-@interface OWSDisappearingMessagesConfigurationTest : XCTestCase
+@interface OWSDisappearingMessagesConfigurationTest : SSKBaseTest
 
 @end
 
diff --git a/SignalServiceKit/tests/Contacts/PhoneNumberTest.m b/SignalServiceKit/tests/Contacts/PhoneNumberTest.m
index 08f20cc26..2848ca316 100644
--- a/SignalServiceKit/tests/Contacts/PhoneNumberTest.m
+++ b/SignalServiceKit/tests/Contacts/PhoneNumberTest.m
@@ -3,9 +3,9 @@
 //
 
 #import "PhoneNumber.h"
-#import <XCTest/XCTest.h>
+#import "SSKBaseTest.h"
 
-@interface PhoneNumberTest : XCTestCase
+@interface PhoneNumberTest : SSKBaseTest
 
 @end
 
diff --git a/SignalServiceKit/tests/Contacts/PhoneNumberUtilTest.m b/SignalServiceKit/tests/Contacts/PhoneNumberUtilTest.m
index 188d1c391..fe8595f74 100644
--- a/SignalServiceKit/tests/Contacts/PhoneNumberUtilTest.m
+++ b/SignalServiceKit/tests/Contacts/PhoneNumberUtilTest.m
@@ -1,11 +1,11 @@
 //
-//  Copyright (c) 2017 Open Whisper Systems. All rights reserved.
+//  Copyright (c) 2018 Open Whisper Systems. All rights reserved.
 //
 
 #import "PhoneNumberUtil.h"
-#import <XCTest/XCTest.h>
+#import "SSKBaseTest.h"
 
-@interface PhoneNumberUtilTest : XCTestCase
+@interface PhoneNumberUtilTest : SSKBaseTest
 
 @end
 
diff --git a/SignalServiceKit/tests/Contacts/SignalRecipientTest.m b/SignalServiceKit/tests/Contacts/SignalRecipientTest.m
index 0e2fbc655..f66501f9c 100644
--- a/SignalServiceKit/tests/Contacts/SignalRecipientTest.m
+++ b/SignalServiceKit/tests/Contacts/SignalRecipientTest.m
@@ -3,10 +3,12 @@
 //
 
 #import "SignalRecipient.h"
+#import "MockSSKEnvironment.h"
+#import "OWSPrimaryStorage.h"
+#import "SSKBaseTest.h"
 #import "TSAccountManager.h"
-
-//#import "TSStorageManager+keyingMaterial.h"
-#import <XCTest/XCTest.h>
+#import "TestAppContext.h"
+#import <SignalServiceKit/SignalServiceKit-Swift.h>
 
 @interface TSAccountManager (Testing)
 
@@ -14,7 +16,7 @@
 
 @end
 
-@interface SignalRecipientTest : XCTestCase
+@interface SignalRecipientTest : SSKBaseTest
 
 @property (nonatomic) NSString *localNumber;
 
diff --git a/SignalServiceKit/tests/Contacts/TSContactThreadTest.m b/SignalServiceKit/tests/Contacts/TSContactThreadTest.m
index 35aef0e47..ac69a8d21 100644
--- a/SignalServiceKit/tests/Contacts/TSContactThreadTest.m
+++ b/SignalServiceKit/tests/Contacts/TSContactThreadTest.m
@@ -1,15 +1,15 @@
 //
-//  Copyright (c) 2017 Open Whisper Systems. All rights reserved.
+//  Copyright (c) 2018 Open Whisper Systems. All rights reserved.
 //
 
 #import "TSContactThread.h"
+#import "MockSSKEnvironment.h"
 #import "OWSIdentityManager.h"
-#import "OWSUnitTestEnvironment.h"
-#import <XCTest/XCTest.h>
+#import "SSKBaseTest.h"
 
 NS_ASSUME_NONNULL_BEGIN
 
-@interface TSContactThreadTest : XCTestCase
+@interface TSContactThreadTest : SSKBaseTest
 
 @property (nonatomic) TSContactThread *contactThread;
 
@@ -19,7 +19,6 @@ NS_ASSUME_NONNULL_BEGIN
 
 - (void)setUp
 {
-    [OWSUnitTestEnvironment ensureSetup];
     self.contactThread = [TSContactThread getOrCreateThreadWithContactId:@"fake-contact-id"];
     [OWSRecipientIdentity removeAllObjectsInCollection];
 }
diff --git a/SignalServiceKit/tests/Contacts/TSGroupThreadTest.m b/SignalServiceKit/tests/Contacts/TSGroupThreadTest.m
index 9dfe91d90..974d36b19 100644
--- a/SignalServiceKit/tests/Contacts/TSGroupThreadTest.m
+++ b/SignalServiceKit/tests/Contacts/TSGroupThreadTest.m
@@ -1,12 +1,13 @@
-//  Created by Michael Kirk on 11/7/16.
-//  Copyright © 2016 Open Whisper Systems. All rights reserved.
+//
+//  Copyright (c) 2018 Open Whisper Systems. All rights reserved.
+//
 
 #import "TSGroupThread.h"
-#import <XCTest/XCTest.h>
+#import "SSKBaseTest.h"
 
 NS_ASSUME_NONNULL_BEGIN
 
-@interface TSGroupThreadTest : XCTestCase
+@interface TSGroupThreadTest : SSKBaseTest
 
 @end
 
diff --git a/SignalServiceKit/tests/Contacts/TSThreadTest.m b/SignalServiceKit/tests/Contacts/TSThreadTest.m
index be71219ba..e8371abd0 100644
--- a/SignalServiceKit/tests/Contacts/TSThreadTest.m
+++ b/SignalServiceKit/tests/Contacts/TSThreadTest.m
@@ -4,16 +4,20 @@
 
 #import "OWSDevice.h"
 #import "OWSPrimaryStorage.h"
+#import "SSKBaseTest.h"
 #import "TSAttachmentStream.h"
 #import "TSContactThread.h"
 #import "TSIncomingMessage.h"
 #import "TSOutgoingMessage.h"
-#import <XCTest/XCTest.h>
+#import "TestAppContext.h"
+#import <SignalServiceKit/SignalServiceKit-Swift.h>
 
-@interface TSThreadTest : XCTestCase
+@interface TSThreadTest : SSKBaseTest
 
 @end
 
+#pragma mark -
+
 @implementation TSThreadTest
 
 - (void)setUp
diff --git a/SignalServiceKit/tests/Devices/OWSDeviceProvisionerTest.m b/SignalServiceKit/tests/Devices/OWSDeviceProvisionerTest.m
index a1b874ca9..1f4293ca8 100644
--- a/SignalServiceKit/tests/Devices/OWSDeviceProvisionerTest.m
+++ b/SignalServiceKit/tests/Devices/OWSDeviceProvisionerTest.m
@@ -6,8 +6,8 @@
 #import "OWSDeviceProvisioningCodeService.h"
 #import "OWSDeviceProvisioningService.h"
 #import "OWSFakeNetworkManager.h"
+#import "SSKBaseTest.h"
 #import "TSNetworkManager.h"
-#import <XCTest/XCTest.h>
 
 @interface OWSFakeDeviceProvisioningService : OWSDeviceProvisioningService
 
@@ -48,7 +48,7 @@
 
 @end
 
-@interface OWSDeviceProvisionerTest : XCTestCase
+@interface OWSDeviceProvisionerTest : SSKBaseTest
 
 @end
 
diff --git a/SignalServiceKit/tests/Messages/Interactions/TSOutgoingMessageTest.m b/SignalServiceKit/tests/Messages/Interactions/TSOutgoingMessageTest.m
index 03c5504f6..bcb297b99 100644
--- a/SignalServiceKit/tests/Messages/Interactions/TSOutgoingMessageTest.m
+++ b/SignalServiceKit/tests/Messages/Interactions/TSOutgoingMessageTest.m
@@ -1,14 +1,15 @@
 //
-//  Copyright (c) 2017 Open Whisper Systems. All rights reserved.
+//  Copyright (c) 2018 Open Whisper Systems. All rights reserved.
 //
 
-#import "TSContactThread.h"
 #import "TSOutgoingMessage.h"
-#import <XCTest/XCTest.h>
+#import "OWSPrimaryStorage.h"
+#import "SSKBaseTest.h"
+#import "TSContactThread.h"
 
 NS_ASSUME_NONNULL_BEGIN
 
-@interface TSOutgoingMessageTest : XCTestCase
+@interface TSOutgoingMessageTest : SSKBaseTest
 
 @property (nonatomic) TSContactThread *thread;
 
diff --git a/SignalServiceKit/tests/SSKBaseTest.h b/SignalServiceKit/tests/SSKBaseTest.h
new file mode 100644
index 000000000..e0957284d
--- /dev/null
+++ b/SignalServiceKit/tests/SSKBaseTest.h
@@ -0,0 +1,13 @@
+//
+//  Copyright (c) 2018 Open Whisper Systems. All rights reserved.
+//
+
+#import <XCTest/XCTest.h>
+
+NS_ASSUME_NONNULL_BEGIN
+
+@interface SSKBaseTest : XCTestCase
+
+@end
+
+NS_ASSUME_NONNULL_END
diff --git a/SignalServiceKit/tests/SSKBaseTest.m b/SignalServiceKit/tests/SSKBaseTest.m
new file mode 100644
index 000000000..e32e30a9c
--- /dev/null
+++ b/SignalServiceKit/tests/SSKBaseTest.m
@@ -0,0 +1,38 @@
+//
+//  Copyright (c) 2018 Open Whisper Systems. All rights reserved.
+//
+
+#import "SSKBaseTest.h"
+#import "OWSPrimaryStorage.h"
+#import "SSKEnvironment.h"
+#import "TestAppContext.h"
+
+NS_ASSUME_NONNULL_BEGIN
+
+@implementation SSKBaseTest
+
+- (void)setUp
+{
+    NSLog(@"%@ setUp", self.logTag);
+
+    [super setUp];
+
+    ClearCurrentAppContextForTests();
+    SetCurrentAppContext([TestAppContext new]);
+}
+
+- (void)tearDown
+{
+    NSLog(@"%@ tearDown", self.logTag);
+
+    [SSKEnvironment.shared.primaryStorage closeStorageForTests];
+
+    ClearCurrentAppContextForTests();
+    [SSKEnvironment clearSharedForTests];
+
+    [super tearDown];
+}
+
+@end
+
+NS_ASSUME_NONNULL_END
diff --git a/SignalServiceKit/tests/Storage/TSStorageSignedPreKeyStore.m b/SignalServiceKit/tests/Storage/TSStorageSignedPreKeyStore.m
index f8d96b9d6..3918c0aa5 100644
--- a/SignalServiceKit/tests/Storage/TSStorageSignedPreKeyStore.m
+++ b/SignalServiceKit/tests/Storage/TSStorageSignedPreKeyStore.m
@@ -1,14 +1,10 @@
 //
-//  TSStorageSignedPreKeyStore.m
-//  TextSecureKit
-//
-//  Created by Frederic Jacobs on 07/11/14.
-//  Copyright (c) 2014 Open Whisper Systems. All rights reserved.
+//  Copyright (c) 2018 Open Whisper Systems. All rights reserved.
 //
 
-#import <XCTest/XCTest.h>
+#import "SSKBaseTest.h"
 
-@interface TSStorageSignedPreKeyStore : XCTestCase
+@interface TSStorageSignedPreKeyStore : SSKBaseTest
 
 @end
 
@@ -24,6 +20,4 @@
     [super tearDown];
 }
 
-
-
 @end
diff --git a/SignalServiceKit/tests/Util/CryptographyTests.m b/SignalServiceKit/tests/Util/CryptographyTests.m
index 215143a59..43605b8a3 100644
--- a/SignalServiceKit/tests/Util/CryptographyTests.m
+++ b/SignalServiceKit/tests/Util/CryptographyTests.m
@@ -3,7 +3,7 @@
 //
 
 #import "Cryptography.h"
-#import "NSData+Base64.h"
+#import "NSData+OWS.h"
 #import <XCTest/XCTest.h>
 
 NS_ASSUME_NONNULL_BEGIN
diff --git a/SignalServiceKit/tests/Util/MessagePaddingTests.m b/SignalServiceKit/tests/Util/MessagePaddingTests.m
index 4b00dcfa2..68933d236 100644
--- a/SignalServiceKit/tests/Util/MessagePaddingTests.m
+++ b/SignalServiceKit/tests/Util/MessagePaddingTests.m
@@ -1,16 +1,12 @@
 //
-//  MessagePaddingTests.m
-//  Signal
-//
-//  Created by Frederic Jacobs on 26/02/15.
-//  Copyright (c) 2015 Open Whisper Systems. All rights reserved.
+//  Copyright (c) 2018 Open Whisper Systems. All rights reserved.
 //
 
 #import "Cryptography.h"
 #import "NSData+messagePadding.h"
-#import <XCTest/XCTest.h>
+#import "SSKBaseTest.h"
 
-@interface MessagePaddingTests : XCTestCase
+@interface MessagePaddingTests : SSKBaseTest
 
 @end
 
diff --git a/SignalServiceKit/tests/Util/OWSAnalyticsTests.m b/SignalServiceKit/tests/Util/OWSAnalyticsTests.m
index c4201fa01..3e0f3e7b1 100644
--- a/SignalServiceKit/tests/Util/OWSAnalyticsTests.m
+++ b/SignalServiceKit/tests/Util/OWSAnalyticsTests.m
@@ -1,14 +1,14 @@
 //
-//  Copyright (c) 2017 Open Whisper Systems. All rights reserved.
+//  Copyright (c) 2018 Open Whisper Systems. All rights reserved.
 //
 
-#import "NSData+Base64.h"
+#import "NSData+OWS.h"
 #import "OWSAnalytics.h"
-#import <XCTest/XCTest.h>
+#import "SSKBaseTest.h"
 
 NS_ASSUME_NONNULL_BEGIN
 
-@interface OWSAnalyticsTests : XCTestCase
+@interface OWSAnalyticsTests : SSKBaseTest
 
 @end
 
diff --git a/SignalServiceKit/tests/Util/SSKSwiftTests.swift b/SignalServiceKit/tests/Util/SSKSwiftTests.swift
new file mode 100644
index 000000000..7287600b5
--- /dev/null
+++ b/SignalServiceKit/tests/Util/SSKSwiftTests.swift
@@ -0,0 +1,8 @@
+//
+//  Copyright (c) 2018 Open Whisper Systems. All rights reserved.
+//
+
+import XCTest
+
+class SSKSwiftTests: XCTestCase {
+}