Add more truthiness tests (#2040)

Author: ddfisher

test-data/unit/check-expressions.test

@@ -310,8 +310,6 @@ i = None # type: str
 j = not b and i
 if j:
     reveal_type(j) # E: Revealed type is 'builtins.str'
-
-
 [builtins fixtures/bool.pyi]
 
 [case testRestrictedTypeOr]
@@ -321,7 +319,13 @@ i = None # type: str
 j = b or i
 if not j:
     reveal_type(j) # E: Revealed type is 'builtins.str'
+[builtins fixtures/bool.pyi]
+
+[case testAndOr]
 
+s = ""
+b = bool()
+reveal_type(s and b or b)  # E: Revealed type is 'builtins.bool'
 [builtins fixtures/bool.pyi]
 
 [case testNonBooleanOr]

test-data/unit/check-isinstance.test

@@ -1165,3 +1165,24 @@ reveal_type(l) # E: Revealed type is 'builtins.list[builtins.int*]'
 reveal_type(g) # E: Revealed type is 'typing.Iterator[builtins.int*]'
 reveal_type(d) # E: Revealed type is 'builtins.dict[builtins.int*, builtins.int*]'
 [builtins fixtures/isinstancelist.pyi]
+
+[case testIsinstanceInWrongOrderInBooleanOp]
+class A:
+    m = 1
+def f(x: object) -> None:
+    if x.m and isinstance(x, A) or False:  # E: "object" has no attribute "m"
+        pass
+[builtins fixtures/isinstance.pyi]
+[out]
+main: note: In function "f":
+
+[case testIsinstanceAndOr]
+class A:
+    a = None  # type: A
+
+def f(x: object) -> None:
+    b = isinstance(x, A) and x.a or A()
+    reveal_type(b)  # E: Revealed type is '__main__.A'
+[builtins fixtures/isinstance.pyi]
+[out]
+main: note: In function "f":

test-data/unit/check-optional.test

@@ -77,6 +77,30 @@ else:
   reveal_type(x)  # E: Revealed type is 'builtins.int'
 [builtins fixtures/bool.pyi]
 
+[case testOrCases]
+from typing import Optional
+x = None  # type: Optional[str]
+y1 = x or 'a'
+reveal_type(y1)  # E: Revealed type is 'builtins.str'
+y2 = x or 1
+reveal_type(y2)  # E: Revealed type is 'Union[builtins.str, builtins.int]'
+z1 = 'a' or x
+reveal_type(z1)  # E: Revealed type is 'Union[builtins.str, builtins.None]'
+z2 = 1 or x
+reveal_type(z2)  # E: Revealed type is 'Union[builtins.int, builtins.str, builtins.None]'
+
+[case testAndCases]
+from typing import Optional
+x = None  # type: Optional[str]
+y1 = x and 'b'
+reveal_type(y1)  # E: Revealed type is 'Union[builtins.str, builtins.None]'
+y2 = x and 1  # x could be '', so...
+reveal_type(y2)  # E: Revealed type is 'Union[builtins.str, builtins.None, builtins.int]'
+z1 = 'b' and x
+reveal_type(z1)  # E: Revealed type is 'Union[builtins.str, builtins.None]'
+z2 = 1 and x
+reveal_type(z2)  # E: Revealed type is 'Union[builtins.int, builtins.str, builtins.None]'
+
 [case testLambdaReturningNone]
 f = lambda: None
 x = f()