Subtract one from 'line-trunc detect' option

This avoids the terminal adding a newline once the terminal line is full.

CHANGELOG.md

@@ -22,6 +22,8 @@ the major/minor/patch definitions apply to the application's interface / usage
 * Added GHC 9.10 support.
 
 ### Fixed
+* Line truncation `detect` option now subtracts one, so terminals do not add
+  an extra newline.
 * More `HasCallStack` annotations for better callstacks in case something goes
   wrong.
 * Increase default `--command-log-read-size` to `16 kb` to better prevent

src/Shrun/Configuration/Data/Truncation.hs

@@ -102,6 +102,10 @@ configToLineTrunc ::
   m (Maybe (Truncation TruncLine))
 configToLineTrunc Disabled = pure Nothing
 configToLineTrunc Without = pure Nothing
-configToLineTrunc (With Detected) = Just . MkTruncation <$> getTerminalWidth
+configToLineTrunc (With Detected) =
+  -- We subtract one because otherwise we can fill the entire terminal with a
+  -- log, which will automatically add a newline. The point of this option is
+  -- to avoid multiple lines, hence the subtraction.
+  Just . MkTruncation . (\x -> x - 1) <$> getTerminalWidth
 configToLineTrunc (With (Undetected x)) = pure $ Just x
 {-# INLINEABLE configToLineTrunc #-}

test/integration/Integration/Miscellaneous.hs

@@ -234,8 +234,8 @@ lineTruncDetect = testPropertyNamed desc "lineTruncDetect"
     args = ["-c", getIntConfig "misc", "cmd1"]
 
     expected =
-      [ #coreConfig % #consoleLogging % #lineTrunc % _Just ^?=@ Just 87,
-        #coreConfig % #fileLogging %? #lineTrunc % _Just ^?=@ Just 87
+      [ #coreConfig % #consoleLogging % #lineTrunc % _Just ^?=@ Just 86,
+        #coreConfig % #fileLogging %? #lineTrunc % _Just ^?=@ Just 86
       ]
 
 testFileSizeModeNothing :: TestTree