tensor variable (#4362)

* tensor variable support

* consttype without variable?

* __setitem__

* symbolic mean works

* arange test

* more tests

* a few more tests

test/test_tensor_variable.py

@@ -0,0 +1,61 @@
+import unittest
+import numpy as np
+from tinygrad import Tensor, Variable
+
+class TestTensorVariable(unittest.TestCase):
+  def test_add_tvar(self):
+    vv = Variable("a", 0, 10)
+    vv.bind(1)
+    ret = (Tensor(vv) + 3).item()
+    assert ret == 4
+
+  def test_inner_tvar_node(self):
+    vv = Variable("w", 0, 10)
+    vv.bind(2)
+    ret = Tensor.from_node(vv * 4).item()
+    assert ret == 8
+
+  def test_inner_tvar_mul(self):
+    vv = Variable("w", 0, 10)
+    vv.bind(2)
+    assert (Tensor(3) * vv).item() == 6
+
+  def test_inner_tvar_mul_node(self):
+    vv = Variable("w", 0, 10)
+    vv.bind(2)
+    assert (Tensor(3) * (vv * 4)).item() == 24
+
+  def test_symbolic_mean(self):
+    vv = Variable("a", 1, 10)
+    vv.bind(2)
+    t = Tensor.ones(2, 2).contiguous().reshape(2, vv)
+    ret = t.mean().item()
+    assert ret == 1
+
+  def test_symbolic_mean_2d(self):
+    vv = Variable("a", 1, 10)
+    vv.bind(2)
+    vv2 = Variable("b", 1, 10)
+    vv2.bind(2)
+    t = Tensor.ones(2, 2).contiguous().reshape(vv2, vv)
+    ret = t.mean().item()
+    assert ret == 1
+
+  def test_symbolic_mean_2d_axis_1(self):
+    vv = Variable("a", 1, 10)
+    vv.bind(2)
+    vv2 = Variable("b", 1, 10)
+    vv2.bind(2)
+    t = Tensor.ones(2, 2).contiguous().reshape(vv2, vv)
+    ret = t.mean(axis=1).reshape(2, 1).numpy()
+    assert np.all(ret == 1)
+
+  @unittest.skip("symbolic arange isn't supported")
+  def test_symbolic_arange(self):
+    vv = Variable("a", 1, 10)
+    vv.bind(2)
+    ret = Tensor.arange(0, vv)
+    ret.realize()
+
+if __name__ == '__main__':
+  unittest.main()

test/unit/test_helpers.py

@@ -143,7 +143,7 @@ class TestRoundUp(unittest.TestCase):
 
 class TestFetch(unittest.TestCase):
   def test_fetch_bad_http(self):
-    self.assertRaises(Exception, fetch, 'http://www.google.com/404')
+    self.assertRaises(Exception, fetch, 'http://www.google.com/404', allow_caching=False)
 
   @unittest.skipIf(not CI, "pre commit tests should run offline")
   def test_fetch_small(self):