tests: add unit tests for ShaderInput comparison (#827)

tests/pgraph/test_shaderinput.py

@@ -0,0 +1,44 @@
+from panda3d.core import ShaderInput, Vec4
+
+
+def test_shaderinput_vector_compare():
+    i0 = ShaderInput('a', Vec4(0, 0, 0, 0))
+    i1 = ShaderInput('a', Vec4(1e-9, 0, 0, 0))
+    i2 = ShaderInput('a', Vec4(1e-8, 0, 0, 0))
+    i3 = ShaderInput('a', Vec4(2, 0, 0, 0))
+
+    assert i0 == i0
+    assert i1 == i1
+    assert i2 == i2
+    assert i3 == i3
+
+    assert i0 != i1
+    assert i0 != i2
+    assert i0 != i3
+    assert i1 != i2
+    assert i2 != i3
+    assert i1 != i3
+
+    assert not i0 < i0
+    assert not i1 < i1
+    assert not i2 < i2
+    assert not i3 < i3
+
+    assert i0 < i1
+    assert i0 < i2
+    assert i0 < i3
+    assert i1 < i2
+    assert i2 < i3
+    assert i1 < i3
+
+    assert not i0 > i0
+    assert not i1 > i1
+    assert not i2 > i2
+    assert not i3 > i3
+
+    assert i3 > i1
+    assert i2 > i1
+    assert i3 > i2
+    assert i1 > i0
+    assert i2 > i0
+    assert i3 > i0