Output compiler verbose log messages to stderr rather than stdout

Author: ascopes

java-compiler-testing/src/main/java/io/github/ascopes/jct/compilers/impl/JctCompilationFactoryImpl.java

@@ -96,7 +96,7 @@ private JctCompilation createCheckedCompilation(
     }
 
     // Do not close stdout, it breaks test engines, especially IntellIJ.
-    var writer = TeeWriter.wrapOutputStream(System.out, compiler.getLogCharset());
+    var writer = TeeWriter.wrapOutputStream(System.err, compiler.getLogCharset());
 
     var diagnosticListener = new TracingDiagnosticListener<>(
         compiler.getDiagnosticLoggingMode() != LoggingMode.DISABLED,

java-compiler-testing/src/test/java/io/github/ascopes/jct/tests/unit/compilers/impl/JctCompilationFactoryImplTest.java

@@ -335,9 +335,9 @@ void anErrorIsRaisedIfNoCompilationUnitsAreFound() throws IOException {
     verifyNoInteractions(javaCompiler);
   }
 
-  @DisplayName("The compiler should write logs to System.out")
+  @DisplayName("The compiler should write logs to System.err")
   @Test
-  void theCompilerShouldWriteLogsToSystemOut() throws IOException {
+  void theCompilerShouldWriteLogsToSystemErr() throws IOException {
     // Given
     try (var teeWriterStatic = mockStatic(TeeWriter.class)) {
       var teeWriter = mock(TeeWriter.class);
@@ -356,7 +356,7 @@ void theCompilerShouldWriteLogsToSystemOut() throws IOException {
 
       // Then
       teeWriterStatic.verify(() -> TeeWriter.wrapOutputStream(
-          System.out,
+          System.err,
           jctCompiler.getLogCharset()
       ));
       teeWriterStatic.verifyNoMoreInteractions();