Use a more informative assertion function.

Cabal/tests/PackageTests/BuildTestSuiteDetailedV09/Check.hs

@@ -13,6 +13,6 @@ suite inplaceSpec ghcPath = TestCase $ do
             , configOpts = "--enable-tests" : configOpts inplaceSpec
             }
     confResult <- cabal_configure spec ghcPath
-    assertEqual "configure failed!" (successful confResult) True
+    assertConfigureSucceeded confResult
     buildResult <- cabal_build spec ghcPath
-    assertEqual "build failed!" (successful buildResult) True
+    assertBuildSucceeded buildResult

Cabal/tests/PackageTests/PackageTester.hs

@@ -19,6 +19,7 @@ module PackageTests.PackageTester
     , run
 
     -- * Test helpers
+    , assertConfigureSucceeded
     , assertBuildSucceeded
     , assertBuildFailed
     , assertHaddockSucceeded
@@ -241,6 +242,12 @@ record spec res = do
 ------------------------------------------------------------------------
 -- * Test helpers
 
+assertConfigureSucceeded :: Result -> Assertion
+assertConfigureSucceeded result = unless (successful result) $
+    assertFailure $
+    "expected: \'setup configure\' should succeed\n" ++
+    "  output: " ++ outputText result
+
 assertBuildSucceeded :: Result -> Assertion
 assertBuildSucceeded result = unless (successful result) $
     assertFailure $