tests: fix vtest being hindrance to error finding.

* tests/common.tl (vtest): Only if the expected expression
is :error or (quote :error) do we wrap the expansion and
evaluation of the test expression with exception handling,
because only then do we expect an error. When the test
expression is anything else, we don't intercept any errors,
and so problems in test cases are easier to debug now.

* tests/012/struct.tl: In one case we must initialize
the *gensym-counter* to 4 to compensate for the change
in vtest to get the same gensym numbers in the output.

1 files changed, 12 insertions, 9 deletions

diff --git a/tests/common.tl b/tests/common.tl
index 157cd7e1..9f7e6eb3 100644
--- a/tests/common.tl
+++ b/tests/common.tl
@@ -3,16 +3,19 @@
     (error (cond) :error)))
 
 (defmacro vtest (:env env expr expected)
- (catch
-   (let ((expr-expn (expand expr env))
-         (expval (gensym)))
-     ^(let ((,expval ,expected))
-        (ifa (not (equal (error-to-sym ,expr-expn) ,expval))
+  (if (mequal expected :error '':error)
+    (catch
+      (let ((expr-expn (expand expr env)))
+        ^(ifa (not (equal (error-to-sym ,expr-expn) :error))
            (error "test case ~s failed: produced ~s; expected ~s"
-                  ',expr it ,expval))))
-   (error (exc)
-          (unless (eq (eval expected) :error)
-            (error "test case ~s failed to expand: expected is ~s" expr expected)))))
+                  ',expr it :error)))
+      (error (exc)))
+    (let ((expr-expn (expand expr env))
+          (expval (gensym)))
+      ^(let ((,expval ,expected))
+         (ifa (not (equal ,expr-expn ,expval))
+           (error "test case ~s failed: produced ~s; expected ~s"
+                  ',expr it ,expval))))))
 
 (defmacro test (expr expected)
   ^(vtest ,expr ',expected))