make the[] error out in invalid position at macro expansion time

Technologicat · Technologicat · commit 4c31d39f15ed · 2021-04-28T03:53:39.000+03:00
diff --git a/unpythonic/syntax/__init__.py b/unpythonic/syntax/__init__.py
@@ -127,7 +127,6 @@
 
 # TODO: Upgrade anaphoric if's `it` into a `mcpyrate` magic variable that errors out at compile time when it appears in an invalid position (i.e. outside any `aif`). Basically, take the `aif` from `mcpyrate`.
 # TODO: also let_syntax block, expr
-# TODO: also the[] in unpythonic.syntax.testingtools
 # TODO: also kw() in unpythonic.syntax.prefix
 # TODO: also call_cc[] in unpythonic.syntax.tailtools
 
diff --git a/unpythonic/syntax/testingtools.py b/unpythonic/syntax/testingtools.py
@@ -357,8 +357,7 @@ def warn_expr(tree):
 # -----------------------------------------------------------------------------
 # Expr variants.
 
-# TODO: convert to mcpyrate magic variable (to raise error when in inappropriate position)
-def the(*args, **kwargs):
+def the(tree, **kw):
     """[syntax, expr] In a test, mark a subexpression as the interesting one.
 
     Only meaningful inside a `test[]`, or inside a `with test` block.
@@ -403,7 +402,7 @@ def the(*args, **kwargs):
 
     For `test_raises` and `test_signals`, the `the[...]` mark is not supported.
     """
-    pass  # pragma: no cover, macro stub
+    raise SyntaxError("the[] is only meaningful inside a `test[]` or in a `with test` block")  # pragma: no cover, not meant to hit the expander
 
 # Destructuring utilities for marking a custom part of the expr
 # to be displayed upon test failure, using `the[...]`:
