test for 'first assignment' algorithm

tests/compile/first_assignment.pyx

+
+cimport cython
+
+@cython.test_assert_path_exists(
+    "//SingleAssignmentNode",
+    "//SingleAssignmentNode[./NameNode[@name = 'a']]",
+    "//SingleAssignmentNode[./NameNode[@name = 'a'] and @first = True]",
+    )
+def test_cdef():
+    cdef int a = 1
+
+@cython.test_assert_path_exists(
+    "//SingleAssignmentNode",
+    "//SingleAssignmentNode[./NameNode[@name = 'a']]",
+# FIXME: currently not working
+#    "//SingleAssignmentNode[./NameNode[@name = 'a'] and @first = True]",
+    )
+def test_py():
+    a = 1
+
+@cython.test_assert_path_exists(
+    "//SingleAssignmentNode",
+    "//SingleAssignmentNode[./NameNode[@name = 'a']]",
+# FIXME: currently not working
+#    "//SingleAssignmentNode[./NameNode[@name = 'a'] and @first = True]",
+    )
+def test_cond():
+    if True:
+        a = 1
+    else:
+        a = 2