Abort tests where coverage cannot be reached

hedgehog-example/src/Test/Example/Confidence.hs

@@ -10,11 +10,14 @@ import qualified Hedgehog.Internal.Gen as Gen
 -- Example 0: This test will certify that it is impossible to get 100%
 --            coverage for the property label "number == 1"
 --
+--            Note that it will abort running once it knows its task is
+--            impossible - it will not run 1000000 tests
+--
 prop_without_confidence :: Property
 prop_without_confidence =
-  withConfidence (10^9) . withTests 100 . property $ do
+  withConfidence (10^9) . withTests 1000000 . property $ do
     number <- forAll (Gen.int $ Range.linear 1 10)
-    cover 100 "number == 1" $ number == 1
+    cover 60 "number == 1" $ number == 1
 
 ------------------------------------------------------------------------
 tests :: IO Bool

hedgehog/src/Hedgehog/Internal/Runner.hs

@@ -191,6 +191,19 @@ checkReport cfg size0 seed0 test0 updateUI =
         -- size has reached limit, reset to 0
         loop tests discards 0 seed coverage0
 
+      else if failureVerified tests coverage0 then
+        -- tests have been verified to not reach coverage for at least one label
+        pure . Report tests discards coverage0 . Failed $
+          mkFailure
+            size
+            seed
+            0
+            (Just coverage0)
+            Nothing
+            "Test coverage cannot be reached, aborted"
+            Nothing
+            []
+
       else if tests >= fromIntegral (propertyTestLimit cfg) then
         -- we've hit the test limit
         if successVerified tests coverage0 then
@@ -207,10 +220,7 @@ checkReport cfg size0 seed0 test0 updateUI =
               0
               (Just coverage0)
               Nothing
-              (if failureVerified tests coverage0 then
-                "Could not meet confidence criteria."
-              else
-                "Insufficient coverage.")
+              "Insufficient coverage."
               Nothing
               []