Hypothesis: Initial support

.gitignore

@@ -0,0 +1,4 @@
+/.cache/
+/*.egg-info/
+__pycache__/
+.hypothesis/

.travis.yml

@@ -11,6 +11,11 @@ matrix:
     allow_failures:
         - python: "nightly"
 
+ cache:
+    directories:
+     - $HOME/.cache/pip
+     - .hypothesis
+
 before_install:
   - if [[ $MINICONDA_OS ]]; then
       URL="https://repo.continuum.io/miniconda/Miniconda3-latest-${MINICONDA_OS}-x86_64.sh";

dev-requirements.txt

@@ -1 +1,2 @@
 pytest~=3.8
+hypothesis

ppb_vector/vector2.py

@@ -1,11 +1,11 @@
 from math import acos, cos, degrees, hypot, radians, sin
-from numbers import Number
+from numbers import Real
 from collections.abc import Sequence
 
 
 class Vector2(Sequence):
 
-    def __init__(self, x, y):
+    def __init__(self, x: Real, y: Real):
         self.x = x
         self.y = y
         self.length = hypot(x, y)
@@ -37,13 +37,13 @@ def __sub__(self, other):
     def __mul__(self, other):
         if isinstance(other, Vector2):
             return self.x * other.x + self.y * other.y
-        elif isinstance(other, Number):
+        elif isinstance(other, Real):
             return Vector2(self.x * other, self.y * other)
         else:
             return NotImplemented
 
     def __rmul__(self, other):
-        if isinstance(other, Number):
+        if isinstance(other, Real):
             return Vector2(self.x * other, self.y * other)
 
     def __xor__(self, other):
@@ -94,6 +94,28 @@ def __neg__(self):
     def angle(self, other):
         return degrees(acos(self.normalize() * other.normalize()))
 
+    def isclose(self, other: 'Vector2', *, rel_tol: float=1e-06, abs_tol: float=1e-3):
+        """
+        Determine whether two vectors are close in value.
+
+           rel_tol
+               maximum difference for being considered "close", relative to the
+               magnitude of the input values
+            abs_tol
+               maximum difference for being considered "close", regardless of the
+               magnitude of the input values
+
+        Return True if self is close in value to other, and False otherwise.
+
+        For the values to be considered close, the difference between them
+        must be smaller than at least one of the tolerances.
+        """
+        diff = (self - other).length
+        return (
+            diff < rel_tol * max(self.length, other.length) or 
+            diff < abs_tol
+        )
+
     def rotate(self, degrees):
         r = radians(degrees)
         r_cos = cos(r)

tests/utils.py

@@ -0,0 +1,18 @@
+from ppb_vector import Vector2
+import hypothesis.strategies as st
+
+vectors = lambda: st.builds(
+    Vector2,
+    st.floats(min_value=-1e300, max_value=1e300),
+    st.floats(min_value=-1e300, max_value=1e300)
+)
+
+@st.composite
+def units(draw, elements=st.floats(min_value=0, max_value=360)):
+    angle = draw(elements)
+    return Vector2(1, 0).rotate(angle)
+
+
+def angle_isclose(x, y, epsilon = 6.5e-5):
+    d = (x - y) % 360
+    return (d < epsilon) or (d > 360 - epsilon)