Use pytest-mypy-plugins to test type annotations

setup.py

@@ -32,7 +32,13 @@ def read(fname):
 assert __version__ is not None
 
 REQUIREMENTS_DOCS = ["sphinx~=3.0", "alabaster~=0.7"]
-TESTS_BASIC = ["pytest>=5.0", "pytest-sugar", "coverage"]
+TESTS_BASIC = [
+    "pytest>=5.0",
+    "pytest-sugar",
+    "coverage",
+    "pytest-mypy-plugins",
+    "types-mock",
+]
 TESTS_NUMPY = ["numpy"]
 DEV_TOOLS = [
     "towncrier",

tests/type-hinting/core/core/test_is.yml

@@ -0,0 +1,10 @@
+- case: is
+  main: |
+    from hamcrest import assert_that, is_, empty
+    from typing import Any, Sequence
+
+    a: Sequence[Any] = []
+    b = 99
+
+    assert_that(a, is_(empty()))
+    assert_that(b, is_(empty()))  # E: Cannot infer type argument 1 of "assert_that"

tests/type-hinting/core/test_assert_that.yml

@@ -0,0 +1,9 @@
+- case: assert_that
+  main: |
+    from hamcrest import assert_that, instance_of, starts_with
+
+    assert_that("string", starts_with("str"))
+    assert_that("str", instance_of(str))
+    assert_that(99, starts_with("str"))
+  out: |
+    main:5: error: Cannot infer type argument 1 of "assert_that"

tests/type-hinting/library/collection/test_empty.yml

@@ -0,0 +1,6 @@
+- case: empty
+  main: |
+    from hamcrest import assert_that, is_, empty
+
+    assert_that([], empty())
+    assert_that(99, empty())  # E: Cannot infer type argument 1 of "assert_that"

tests/type-hinting/library/text/test_equal_to_ignoring_case.yml

@@ -0,0 +1,10 @@
+- case: equal_to_ignoring_case
+  main: |
+    from hamcrest import equal_to_ignoring_case
+
+    reveal_type(equal_to_ignoring_case(""))
+    equal_to_ignoring_case("")
+    equal_to_ignoring_case(99)
+  out: |
+    main:3: note: Revealed type is "hamcrest.core.matcher.Matcher[builtins.str]"
+    main:5: error: Argument 1 to "equal_to_ignoring_case" has incompatible type "int"; expected "str"