diff --git a/mypy/test/testcheck.py b/mypy/test/testcheck.py
index c9e66e4270b6..1e5c47c2be25 100644
--- a/mypy/test/testcheck.py
+++ b/mypy/test/testcheck.py
@@ -55,33 +55,20 @@
     "check-bound.test",
     "check-dynamic-typing.test",
     "check-expressions.test",
-    "check-formatting.test",
     "check-functions.test",
     "check-generic-subtyping.test",
     "check-generics.test",
-    "check-incremental.test",
     "check-inference-context.test",
     "check-inference.test",
-    "check-inline-config.test",
     "check-isinstance.test",
     "check-kwargs.test",
-    "check-lists.test",
     "check-literal.test",
     "check-modules.test",
     "check-namedtuple.test",
-    "check-newsemanal.test",
     "check-overloading.test",
     "check-plugin-attrs.test",
-    "check-protocols.test",
-    "check-selftype.test",
-    "check-serialize.test",
     "check-statements.test",
-    "check-super.test",
     "check-tuples.test",
-    "check-type-aliases.test",
-    "check-type-checks.test",
-    "check-typeddict.test",
-    "check-typevar-values.test",
     "check-unions.test",
     "check-varargs.test",
 }
diff --git a/test-data/unit/check-formatting.test b/test-data/unit/check-formatting.test
index 588b2c11714e..f63abbb33034 100644
--- a/test-data/unit/check-formatting.test
+++ b/test-data/unit/check-formatting.test
@@ -4,7 +4,10 @@
 
 [case testStringInterpolationType]
 from typing import Tuple
-i, f, s, t = None, None, None, None # type: (int, float, str, Tuple[int])
+i: int
+f: float
+s: str
+t: Tuple[int]
 '%d' % i
 '%f' % f
 '%s' % s
@@ -21,7 +24,9 @@ i, f, s, t = None, None, None, None # type: (int, float, str, Tuple[int])
 
 [case testStringInterpolationSAcceptsAnyType]
 from typing import Any
-i, o, s = None, None, None # type: (int, object, str)
+i: int
+o: object
+s: str
 '%s %s %s' % (i, o, s)
 [builtins fixtures/primitives.pyi]
 
@@ -139,8 +144,10 @@ class BytesThing:
     def __getitem__(self, __key: bytes) -> str:
         ...
 
-a = None # type: Any
-ds, do, di = None, None, None # type: Dict[str, int], Dict[object, int], Dict[int, int]
+a: Any
+ds: Dict[str, int]
+do: Dict[object, int]
+di: Dict[int, int]
 '%(a)' % 1  # E: Format requires a mapping (expression has type "int", expected type for mapping is "SupportsKeysAndGetItem[str, Any]")
 '%()d' % a
 '%()d' % ds
diff --git a/test-data/unit/check-incremental.test b/test-data/unit/check-incremental.test
index c3153cd8643a..5203b0828122 100644
--- a/test-data/unit/check-incremental.test
+++ b/test-data/unit/check-incremental.test
@@ -1734,12 +1734,12 @@ class R: pass
 [file r/s.py]
 from . import m
 R = m.R
-a = None  # type: R
+a: R
 
 [file r/s.py.2]
 from . import m
 R = m.R
-a = None  # type: R
+a: R
 
 [case testIncrementalBaseClassAttributeConflict]
 class A: pass
@@ -2603,7 +2603,7 @@ def output() -> IntNode[str]:
     return Node(1, 'x')
 x = output() # type: IntNode
 
-y = None # type: IntNode
+y: IntNode
 y.x = 1
 y.y = 1
 y.y = 'x'
@@ -2625,7 +2625,7 @@ def output() -> IntNode[str]:
     return Node(1, 'x')
 x = output() # type: IntNode
 
-y = None # type: IntNode
+y: IntNode
 y.x = 1
 y.y = 1
 y.y = 'x'
diff --git a/test-data/unit/check-inline-config.test b/test-data/unit/check-inline-config.test
index 0cc2bd71270a..71030b5c9b97 100644
--- a/test-data/unit/check-inline-config.test
+++ b/test-data/unit/check-inline-config.test
@@ -4,8 +4,8 @@
 
 # mypy: disallow-any-generics, no-warn-no-return
 
-from typing import List
-def foo() -> List:  # E: Missing type parameters for generic type "List"
+from typing import List, Optional
+def foo() -> Optional[List]:  # E: Missing type parameters for generic type "List"
     20
 
 [builtins fixtures/list.pyi]
@@ -15,8 +15,8 @@ def foo() -> List:  # E: Missing type parameters for generic type "List"
 # mypy: disallow-any-generics
 # mypy: no-warn-no-return
 
-from typing import List
-def foo() -> List:  # E: Missing type parameters for generic type "List"
+from typing import List, Optional
+def foo() -> Optional[List]:  # E: Missing type parameters for generic type "List"
     20
 
 [builtins fixtures/list.pyi]
@@ -25,8 +25,8 @@ def foo() -> List:  # E: Missing type parameters for generic type "List"
 
 # mypy: disallow-any-generics=true, warn-no-return=0
 
-from typing import List
-def foo() -> List:  # E: Missing type parameters for generic type "List"
+from typing import List, Optional
+def foo() -> Optional[List]:  # E: Missing type parameters for generic type "List"
     20
 
 [builtins fixtures/list.pyi]
@@ -36,8 +36,8 @@ def foo() -> List:  # E: Missing type parameters for generic type "List"
 
 # mypy: disallow-any-generics = true, warn-no-return = 0
 
-from typing import List
-def foo() -> List:  # E: Missing type parameters for generic type "List"
+from typing import List, Optional
+def foo() -> Optional[List]:  # E: Missing type parameters for generic type "List"
     20
 
 [builtins fixtures/list.pyi]
@@ -84,20 +84,20 @@ import a
 [file a.py]
 # mypy: disallow-any-generics, no-warn-no-return
 
-from typing import List
-def foo() -> List:
+from typing import List, Optional
+def foo() -> Optional[List]:
     20
 
 [file a.py.2]
 # mypy: no-warn-no-return
 
-from typing import List
-def foo() -> List:
+from typing import List, Optional
+def foo() -> Optional[List]:
     20
 
 [file a.py.3]
-from typing import List
-def foo() -> List:
+from typing import List, Optional
+def foo() -> Optional[List]:
     20
 [out]
 tmp/a.py:4: error: Missing type parameters for generic type "List"
@@ -131,8 +131,9 @@ tmp/a.py:4: error: Missing type parameters for generic type "List"
 import a, b
 [file a.py]
 # mypy: no-warn-no-return
+from typing import Optional
 
-def foo() -> int:
+def foo() -> Optional[int]:
     20
 
 [file b.py]
diff --git a/test-data/unit/check-lists.test b/test-data/unit/check-lists.test
index 899b7c5b209f..9809024afdbb 100644
--- a/test-data/unit/check-lists.test
+++ b/test-data/unit/check-lists.test
@@ -3,8 +3,12 @@
 
 [case testNestedListAssignment]
 from typing import List
-a1, b1, c1 = None, None, None # type: (A, B, C)
-a2, b2, c2 = None, None, None # type: (A, B, C)
+a1: A
+a2: A
+b1: B
+b2: B
+c1: C
+c2: C
 
 if int():
     a1, [b1, c1] = a2, [b2, c2]
@@ -21,7 +25,9 @@ class C: pass
 
 [case testNestedListAssignmentToTuple]
 from typing import List
-a, b, c = None, None, None # type: (A, B, C)
+a: A
+b: B
+c: C
 
 a, b = [a, b]
 a, b = [a]  # E: Need more than 1 value to unpack (2 expected)
@@ -35,7 +41,9 @@ class C: pass
 
 [case testListAssignmentFromTuple]
 from typing import List
-a, b, c = None, None, None # type: (A, B, C)
+a: A
+b: B
+c: C
 t = a, b
 
 if int():
@@ -55,7 +63,9 @@ class C: pass
 
 [case testListAssignmentUnequalAmountToUnpack]
 from typing import List
-a, b, c = None, None, None # type: (A, B, C)
+a: A
+b: B
+c: C
 
 def f() -> None: # needed because test parser tries to parse [a, b] as section header
     [a, b] = [a, b]
diff --git a/test-data/unit/check-newsemanal.test b/test-data/unit/check-newsemanal.test
index de8212b3e695..77a1553d4715 100644
--- a/test-data/unit/check-newsemanal.test
+++ b/test-data/unit/check-newsemanal.test
@@ -2149,6 +2149,7 @@ x: C
 class C:
     def frob(self, foos: Dict[Any, Foos]) -> None:
         foo = foos.get(1)
+        assert foo
         dict(foo)
 [builtins fixtures/dict.pyi]
 
diff --git a/test-data/unit/check-protocols.test b/test-data/unit/check-protocols.test
index 6ba1fde4d022..5d5ba54304a3 100644
--- a/test-data/unit/check-protocols.test
+++ b/test-data/unit/check-protocols.test
@@ -319,7 +319,9 @@ class MyHashable(Protocol):
 class C:
     __my_hash__ = None
 
-var: MyHashable = C()  # E: Incompatible types in assignment (expression has type "C", variable has type "MyHashable")
+var: MyHashable = C()  # E: Incompatible types in assignment (expression has type "C", variable has type "MyHashable") \
+                       # N: Following member(s) of "C" have conflicts: \
+                       # N:     __my_hash__: expected "Callable[[], int]", got "None"
 
 [case testNoneDisablesProtocolSubclassingWithStrictOptional]
 # flags: --strict-optional
@@ -1263,13 +1265,13 @@ if int():
 [builtins fixtures/classmethod.pyi]
 
 [case testOverloadedMethodsInProtocols]
-from typing import overload, Protocol, Union
+from typing import overload, Protocol, Union, Optional
 
 class P(Protocol):
     @overload
-    def f(self, x: int) -> int: pass
+    def f(self, x: int) -> Optional[int]: pass
     @overload
-    def f(self, x: str) -> str: pass
+    def f(self, x: str) -> Optional[str]: pass
 
 class C:
     def f(self, x: Union[int, str]) -> None:
@@ -1286,9 +1288,9 @@ main:18: error: Incompatible types in assignment (expression has type "D", varia
 main:18: note: Following member(s) of "D" have conflicts:
 main:18: note:     Expected:
 main:18: note:         @overload
-main:18: note:         def f(self, x: int) -> int
+main:18: note:         def f(self, x: int) -> Optional[int]
 main:18: note:         @overload
-main:18: note:         def f(self, x: str) -> str
+main:18: note:         def f(self, x: str) -> Optional[str]
 main:18: note:     Got:
 main:18: note:         def f(self, x: int) -> None
 
@@ -1441,6 +1443,7 @@ def g(x: P, y: P2) -> None: pass
 reveal_type(f(g)) # N: Revealed type is "__main__.P2"
 
 [case testMeetOfIncompatibleProtocols]
+# flags: --no-strict-optional
 from typing import Protocol, Callable, TypeVar
 
 class P(Protocol):
@@ -1634,6 +1637,7 @@ f(Alias)  # E: Only concrete class can be given where "Type[P]" is expected
 f(GoodAlias)
 
 [case testInstantiationProtocolInTypeForVariables]
+# flags: --no-strict-optional
 from typing import Type, Protocol
 
 class P(Protocol):
@@ -2397,6 +2401,7 @@ x: P = None
 [out]
 
 [case testNoneSubtypeOfAllProtocolsWithoutStrictOptional]
+# flags: --no-strict-optional
 from typing import Protocol
 class P(Protocol):
     attr: int
diff --git a/test-data/unit/check-selftype.test b/test-data/unit/check-selftype.test
index dc7a6c239fe6..d366e7c33799 100644
--- a/test-data/unit/check-selftype.test
+++ b/test-data/unit/check-selftype.test
@@ -897,7 +897,8 @@ class Base(Protocol):
 
 class TweakFunc:
     def func(self: Base) -> int:
-        return reveal_type(super().func())  # N: Revealed type is "builtins.int"
+        return reveal_type(super().func())  # E: Call to abstract method "func" of "Base" with trivial body via super() is unsafe \
+                                            # N: Revealed type is "builtins.int"
 
 class Good:
     def func(self) -> int: ...
@@ -1269,14 +1270,14 @@ class AClass:
         ...
 
 def foo(x: Type[AClass]) -> None:
-    reveal_type(x.delete)  # N: Revealed type is "Overload(def (id: builtins.int, id2: builtins.int) -> builtins.int, def (id: __main__.AClass, id2: None =) -> builtins.int)"
+    reveal_type(x.delete)  # N: Revealed type is "Overload(def (id: builtins.int, id2: builtins.int) -> Union[builtins.int, None], def (id: __main__.AClass, id2: None =) -> Union[builtins.int, None])"
     y = x()
-    reveal_type(y.delete)  # N: Revealed type is "Overload(def (id: builtins.int, id2: builtins.int) -> builtins.int, def (id: __main__.AClass, id2: None =) -> builtins.int)"
+    reveal_type(y.delete)  # N: Revealed type is "Overload(def (id: builtins.int, id2: builtins.int) -> Union[builtins.int, None], def (id: __main__.AClass, id2: None =) -> Union[builtins.int, None])"
     y.delete(10, 20)
     y.delete(y)
 
 def bar(x: AClass) -> None:
-    reveal_type(x.delete)  # N: Revealed type is "Overload(def (id: builtins.int, id2: builtins.int) -> builtins.int, def (id: __main__.AClass, id2: None =) -> builtins.int)"
+    reveal_type(x.delete)  # N: Revealed type is "Overload(def (id: builtins.int, id2: builtins.int) -> Union[builtins.int, None], def (id: __main__.AClass, id2: None =) -> Union[builtins.int, None])"
     x.delete(10, 20)
 [builtins fixtures/classmethod.pyi]
 
diff --git a/test-data/unit/check-serialize.test b/test-data/unit/check-serialize.test
index 66d5d879ae68..e5d1d6b170f9 100644
--- a/test-data/unit/check-serialize.test
+++ b/test-data/unit/check-serialize.test
@@ -1275,6 +1275,7 @@ main:2: error: Too many arguments for "f"
 main:2: error: Too many arguments for "f"
 
 [case testSerializeDummyType]
+# flags: --no-strict-optional
 import a
 [file a.py]
 import b
diff --git a/test-data/unit/check-super.test b/test-data/unit/check-super.test
index b3379e505be7..48a0a0250ecf 100644
--- a/test-data/unit/check-super.test
+++ b/test-data/unit/check-super.test
@@ -11,7 +11,8 @@ class B:
   def f(self) -> 'B': pass
 class A(B):
   def f(self) -> 'A':
-    a, b = None, None # type: (A, B)
+    a: A
+    b: B
     if int():
         a = super().f() # E: Incompatible types in assignment (expression has type "B", variable has type "A")
         a = super().g() # E: "g" undefined in superclass
@@ -26,7 +27,8 @@ class B:
   def f(self, y: 'A') -> None: pass
 class A(B):
   def f(self, y: Any) -> None:
-    a, b = None, None # type: (A, B)
+    a: A
+    b: B
     super().f(b) # E: Argument 1 to "f" of "B" has incompatible type "B"; expected "A"
     super().f(a)
     self.f(b)
@@ -35,6 +37,7 @@ class A(B):
 [out]
 
 [case testAccessingSuperInit]
+# flags: --no-strict-optional
 import typing
 class B:
     def __init__(self, x: A) -> None: pass
@@ -90,7 +93,7 @@ class B(A):
     def __new__(cls, x: int, y: str = '') -> 'B':
         super().__new__(cls, 1)
         super().__new__(cls, 1, '')  # E: Too many arguments for "__new__" of "A"
-        return None
+        return cls(1)
 B('')  # E: Argument 1 to "B" has incompatible type "str"; expected "int"
 B(1)
 B(1, 'x')
diff --git a/test-data/unit/check-type-aliases.test b/test-data/unit/check-type-aliases.test
index 05a03ecaf7b0..3bfcf6a9afea 100644
--- a/test-data/unit/check-type-aliases.test
+++ b/test-data/unit/check-type-aliases.test
@@ -28,7 +28,7 @@ f(1) # E: Argument 1 to "f" has incompatible type "int"; expected "Tuple[int, st
 [case testCallableTypeAlias]
 from typing import Callable
 A = Callable[[int], None]
-f = None  # type: A
+f: A
 f(1)
 f('') # E: Argument 1 has incompatible type "str"; expected "int"
 [targets __main__]
@@ -169,11 +169,11 @@ f(1) # E: Argument 1 to "f" has incompatible type "int"; expected "str"
 [case testEmptyTupleTypeAlias]
 from typing import Tuple, Callable
 EmptyTuple = Tuple[()]
-x = None # type: EmptyTuple
+x: EmptyTuple
 reveal_type(x)  # N: Revealed type is "Tuple[]"
 
 EmptyTupleCallable = Callable[[Tuple[()]], None]
-f = None # type: EmptyTupleCallable
+f: EmptyTupleCallable
 reveal_type(f)  # N: Revealed type is "def (Tuple[])"
 [builtins fixtures/list.pyi]
 
diff --git a/test-data/unit/check-type-checks.test b/test-data/unit/check-type-checks.test
index 106f2d680ba4..03c8de4177f3 100644
--- a/test-data/unit/check-type-checks.test
+++ b/test-data/unit/check-type-checks.test
@@ -2,9 +2,9 @@
 
 
 [case testSimpleIsinstance]
-x = None  # type: object
-n = None  # type: int
-s = None  # type: str
+x: object
+n: int
+s: str
 if int():
     n = x # E: Incompatible types in assignment (expression has type "object", variable has type "int")
 if isinstance(x, int):
diff --git a/test-data/unit/check-typeddict.test b/test-data/unit/check-typeddict.test
index 4d2d64848515..739d1ba6eb75 100644
--- a/test-data/unit/check-typeddict.test
+++ b/test-data/unit/check-typeddict.test
@@ -1121,8 +1121,8 @@ D = TypedDict('D', {'x': int, 'y': str}, total=False)
 d: D
 reveal_type(d['x']) # N: Revealed type is "builtins.int"
 reveal_type(d['y']) # N: Revealed type is "builtins.str"
-reveal_type(d.get('x')) # N: Revealed type is "builtins.int"
-reveal_type(d.get('y')) # N: Revealed type is "builtins.str"
+reveal_type(d.get('x')) # N: Revealed type is "Union[builtins.int, None]"
+reveal_type(d.get('y')) # N: Revealed type is "Union[builtins.str, None]"
 [builtins fixtures/dict.pyi]
 [typing fixtures/typing-typeddict.pyi]
 
@@ -1642,7 +1642,7 @@ def f1(x: int, y: str, z: bytes) -> None: ...
 def f2(x: int, y: str) -> None: ...
 
 td: TD
-d = None # type: Dict[Any, Any]
+d: Dict[Any, Any]
 
 f1(**td, **d)
 f1(**d, **td)
@@ -1740,8 +1740,8 @@ class TDB(TypedDict):
 
 td: Union[TDA, TDB]
 
-reveal_type(td.get('a'))  # N: Revealed type is "builtins.int"
-reveal_type(td.get('b'))  # N: Revealed type is "Union[builtins.str, builtins.int]"
+reveal_type(td.get('a'))  # N: Revealed type is "Union[builtins.int, None]"
+reveal_type(td.get('b'))  # N: Revealed type is "Union[builtins.str, None, builtins.int]"
 reveal_type(td.get('c'))  # N: Revealed type is "builtins.object"
 
 reveal_type(td['a'])  # N: Revealed type is "builtins.int"
@@ -1805,7 +1805,7 @@ from mypy_extensions import TypedDict
 class A(TypedDict):
     x: int
 
-d: Union[A, None]
+d: A
 d.update({'x': 1})
 [builtins fixtures/dict.pyi]
 
diff --git a/test-data/unit/check-typevar-values.test b/test-data/unit/check-typevar-values.test
index 83340c52b63b..effaf620f1f0 100644
--- a/test-data/unit/check-typevar-values.test
+++ b/test-data/unit/check-typevar-values.test
@@ -97,8 +97,8 @@ def f(x: AB) -> AB:
 from typing import TypeVar
 T = TypeVar('T', int, str)
 def f(x: T) -> T:
-    a = None  # type: T
-    b = None # type: T
+    a: T
+    b: T
     if 1:
         a = x
         b = x
@@ -248,10 +248,10 @@ def g(a: T) -> None:
 from typing import TypeVar, Generic, Any
 X = TypeVar('X', int, str)
 class A(Generic[X]): pass
-a = None  # type: A[int]
-b = None  # type: A[str]
-d = None  # type: A[object] # E: Value of type variable "X" of "A" cannot be "object"
-c = None  # type: A[Any]
+a: A[int]
+b: A[str]
+d: A[object]  # E: Value of type variable "X" of "A" cannot be "object"
+c: A[Any]
 
 [case testConstructGenericTypeWithTypevarValuesAndTypeInference]
 from typing import TypeVar, Generic, Any, cast
@@ -272,11 +272,11 @@ Z = TypeVar('Z')
 class D(Generic[X]):
     def __init__(self, x: X) -> None: pass
 def f(x: X) -> None:
-    a = None  # type: D[X]
+    a: D[X]
 def g(x: Y) -> None:
-    a = None  # type: D[Y]
+    a: D[Y]
 def h(x: Z) -> None:
-    a = None  # type: D[Z]
+    a: D[Z]
 [out]
 main:11: error: Invalid type argument value for "D"
 main:13: error: Type variable "Z" not valid as type argument value for "D"
@@ -287,7 +287,7 @@ X = TypeVar('X', int, str)
 class S(str): pass
 class C(Generic[X]):
     def __init__(self, x: X) -> None: pass
-x = None  # type: C[str]
+x: C[str]
 y = C(S())
 if int():
     x = y
@@ -412,10 +412,10 @@ class B: pass
 X = TypeVar('X', A, B)
 Y = TypeVar('Y', int, str)
 class C(Generic[X, Y]): pass
-a = None  # type: C[A, int]
-b = None  # type: C[B, str]
-c = None  # type: C[int, int] # E: Value of type variable "X" of "C" cannot be "int"
-d = None  # type: C[A, A]     # E: Value of type variable "Y" of "C" cannot be "A"
+a: C[A, int]
+b: C[B, str]
+c: C[int, int]  # E: Value of type variable "X" of "C" cannot be "int"
+d: C[A, A]      # E: Value of type variable "Y" of "C" cannot be "A"
 
 [case testCallGenericFunctionUsingMultipleTypevarsWithValues]
 from typing import TypeVar
@@ -512,7 +512,7 @@ class C(A[str]):
 from typing import TypeVar, Generic
 T = TypeVar('T', int, str)
 class C(Generic[T]):
-    def f(self, x: int = None) -> None: pass
+    def f(self, x: int = 2) -> None: pass
 
 [case testTypevarValuesWithOverloadedFunctionSpecialCase]
 from foo import *