Improve the failure messages when tests fail. (#298)

- The line numbers in the error messages now refer to the function that
  calls `shouldBe*`, instead of the location of the assertion inside of
  `shouldBe*`.

- The error messages now include the actual exit code, stdout and
  stderr from the failed invocation.

- The slight downside of this change is that the expected value for
  code/stdout/stderr no longer appears in the error message. Expected
  values are normally easily visible in the test code itself, so this
  should not be too painful.

test/Utils.hs

@@ -16,7 +16,7 @@ import qualified Control.Exception as Exception
 import Prelude hiding (FilePath)
 import System.Directory (removePathForcibly)
 import qualified System.Process as Process
-import Test.Hspec (shouldBe)
+import Test.Hspec (HasCallStack, shouldBe, shouldSatisfy)
 import Turtle (ExitCode (..), FilePath, Text, cd, empty, encodeString,
  procStrictWithErr, pwd, readTextFile)
 
@@ -35,33 +35,33 @@ runFor us cmd args = do
  Concurrent.threadDelay us
  Process.terminateProcess p
 
-shouldBeSuccess :: (ExitCode, Text, Text) -> IO ()
-shouldBeSuccess (code, _stdout, _stderr) = do
+shouldBeSuccess :: HasCallStack => (ExitCode, Text, Text) -> IO ()
+shouldBeSuccess result@(_code, _stdout, _stderr) = do
  -- print $ "STDOUT: " <> _stdout
  -- print $ "STDERR: " <> _stderr
- code `shouldBe` ExitSuccess
+ result `shouldSatisfy` (\(code, _, _) -> code == ExitSuccess)
 
-shouldBeSuccessOutput :: FilePath -> (ExitCode, Text, Text) -> IO ()
-shouldBeSuccessOutput expected (code, out, _) = do
+shouldBeSuccessOutput :: HasCallStack => FilePath -> (ExitCode, Text, Text) -> IO ()
+shouldBeSuccessOutput expected result = do
  expectedContent <- readFixture expected
- (code, out) `shouldBe` (ExitSuccess, expectedContent)
+ result `shouldSatisfy` (\(code, stdout, _stderr) -> code == ExitSuccess && stdout == expectedContent)
 
-shouldBeFailure :: (ExitCode, Text, Text) -> IO ()
-shouldBeFailure (code, _stdout, _stderr) = do
+shouldBeFailure :: HasCallStack => (ExitCode, Text, Text) -> IO ()
+shouldBeFailure result@(_code, _stdout, _stderr) = do
  -- print $ "STDOUT: " <> _stdout
  -- print $ "STDERR: " <> _stderr
- code `shouldBe` ExitFailure 1
+ result `shouldSatisfy` (\(code, _, _) -> code == ExitFailure 1)
 
-shouldBeFailureOutput :: FilePath -> (ExitCode, Text, Text) -> IO ()
-shouldBeFailureOutput expected (code, _, out) = do
+shouldBeFailureOutput :: HasCallStack => FilePath -> (ExitCode, Text, Text) -> IO ()
+shouldBeFailureOutput expected result = do
  expectedContent <- readFixture expected
- (code, out) `shouldBe` (ExitFailure 1, expectedContent)
+ result `shouldSatisfy` (\(code, _stdout, stderr) -> code == ExitFailure 1 && stderr == expectedContent)
 
 readFixture :: FilePath -> IO Text
 readFixture path =
  readTextFile $ "../fixtures/" <> path
 
-checkFixture :: FilePath -> IO ()
+checkFixture :: HasCallStack => FilePath -> IO ()
 checkFixture path = do
  actual <- readTextFile path
  expected <- readFixture path