Feature/remove app context (#765)

* Remove AppContext. Use StdChannels to hold writers, and TestToolUtil to hold test tool specific functionality.

* StdChannels -> StdWriters

* getStdOut -> getOut, getStdError -> getError

19 files changed, 202 insertions, 182 deletions

diff --git a/source/core/core.vcxproj b/source/core/core.vcxproj
index 5dad716fb..bebf7350c 100644
--- a/source/core/core.vcxproj
+++ b/source/core/core.vcxproj
@@ -182,7 +182,6 @@
     <ClInclude Include="list.h" />
     <ClInclude Include="platform.h" />
     <ClInclude Include="secure-crt.h" />
-    <ClInclude Include="slang-app-context.h" />
     <ClInclude Include="slang-byte-encode-util.h" />
     <ClInclude Include="slang-cpu-defines.h" />
     <ClInclude Include="slang-free-list.h" />
@@ -192,9 +191,11 @@
     <ClInclude Include="slang-object-scope-manager.h" />
     <ClInclude Include="slang-random-generator.h" />
     <ClInclude Include="slang-shared-library.h" />
+    <ClInclude Include="slang-std-writers.h" />
     <ClInclude Include="slang-string-slice-pool.h" />
     <ClInclude Include="slang-string-util.h" />
     <ClInclude Include="slang-string.h" />
+    <ClInclude Include="slang-test-tool-util.h" />
     <ClInclude Include="slang-writer.h" />
     <ClInclude Include="smart-pointer.h" />
     <ClInclude Include="stream.h" />
@@ -204,7 +205,6 @@
   </ItemGroup>
   <ItemGroup>
     <ClCompile Include="platform.cpp" />
-    <ClCompile Include="slang-app-context.cpp" />
     <ClCompile Include="slang-byte-encode-util.cpp" />
     <ClCompile Include="slang-free-list.cpp" />
     <ClCompile Include="slang-io.cpp" />
@@ -212,9 +212,11 @@
     <ClCompile Include="slang-object-scope-manager.cpp" />
     <ClCompile Include="slang-random-generator.cpp" />
     <ClCompile Include="slang-shared-library.cpp" />
+    <ClCompile Include="slang-std-writers.cpp" />
     <ClCompile Include="slang-string-slice-pool.cpp" />
     <ClCompile Include="slang-string-util.cpp" />
     <ClCompile Include="slang-string.cpp" />
+    <ClCompile Include="slang-test-tool-util.cpp" />
     <ClCompile Include="slang-writer.cpp" />
     <ClCompile Include="stream.cpp" />
     <ClCompile Include="text-io.cpp" />
diff --git a/source/core/core.vcxproj.filters b/source/core/core.vcxproj.filters
index c5c1fc733..dd33b61f9 100644
--- a/source/core/core.vcxproj.filters
+++ b/source/core/core.vcxproj.filters
@@ -45,9 +45,6 @@
     <ClInclude Include="secure-crt.h">
       <Filter>Header Files</Filter>
     </ClInclude>
-    <ClInclude Include="slang-app-context.h">
-      <Filter>Header Files</Filter>
-    </ClInclude>
     <ClInclude Include="slang-byte-encode-util.h">
       <Filter>Header Files</Filter>
     </ClInclude>
@@ -75,6 +72,9 @@
     <ClInclude Include="slang-shared-library.h">
       <Filter>Header Files</Filter>
     </ClInclude>
+    <ClInclude Include="slang-std-writers.h">
+      <Filter>Header Files</Filter>
+    </ClInclude>
     <ClInclude Include="slang-string-slice-pool.h">
       <Filter>Header Files</Filter>
     </ClInclude>
@@ -84,6 +84,9 @@
     <ClInclude Include="slang-string.h">
       <Filter>Header Files</Filter>
     </ClInclude>
+    <ClInclude Include="slang-test-tool-util.h">
+      <Filter>Header Files</Filter>
+    </ClInclude>
     <ClInclude Include="slang-writer.h">
       <Filter>Header Files</Filter>
     </ClInclude>
@@ -107,9 +110,6 @@
     <ClCompile Include="platform.cpp">
       <Filter>Source Files</Filter>
     </ClCompile>
-    <ClCompile Include="slang-app-context.cpp">
-      <Filter>Source Files</Filter>
-    </ClCompile>
     <ClCompile Include="slang-byte-encode-util.cpp">
       <Filter>Source Files</Filter>
     </ClCompile>
@@ -131,6 +131,9 @@
     <ClCompile Include="slang-shared-library.cpp">
       <Filter>Source Files</Filter>
     </ClCompile>
+    <ClCompile Include="slang-std-writers.cpp">
+      <Filter>Source Files</Filter>
+    </ClCompile>
     <ClCompile Include="slang-string-slice-pool.cpp">
       <Filter>Source Files</Filter>
     </ClCompile>
@@ -140,6 +143,9 @@
     <ClCompile Include="slang-string.cpp">
       <Filter>Source Files</Filter>
     </ClCompile>
+    <ClCompile Include="slang-test-tool-util.cpp">
+      <Filter>Source Files</Filter>
+    </ClCompile>
     <ClCompile Include="slang-writer.cpp">
       <Filter>Source Files</Filter>
     </ClCompile>
diff --git a/source/core/slang-app-context.cpp b/source/core/slang-app-context.cpp
deleted file mode 100644
index 2b3f32cbc..000000000
--- a/source/core/slang-app-context.cpp
+++ /dev/null
@@ -1,67 +0,0 @@
-
-#include "slang-app-context.h"
-
-#include "slang-writer.h"
-
-namespace Slang
-{
-
-/* static */AppContext* AppContext::s_singleton = nullptr;
-
-
-/* static */AppContext* AppContext::getDefault()
-{
-    static AppContext* s_context = nullptr;
-
-    if (!s_context)
-    {
-        static FileWriter s_stdError(stderr, WriterFlag::IsStatic | WriterFlag::IsUnowned | WriterFlag::AutoFlush);
-        static FileWriter s_stdOut(stdout, WriterFlag::IsStatic | WriterFlag::IsUnowned | WriterFlag::AutoFlush);
-
-        static AppContext s_contextVar;
-        s_context = &s_contextVar;
-
-        s_context->setWriter(SLANG_WRITER_CHANNEL_STD_ERROR, &s_stdError);
-        s_context->setWriter(SLANG_WRITER_CHANNEL_STD_OUTPUT, &s_stdOut);
-    }
-    return s_context;
-}
-
-/* static */AppContext* AppContext::initDefault()
-{
-    AppContext* context = getDefault();
-    setSingleton(context);
-    return context;
-}
-
-/* static */int AppContext::getReturnCode(SlangResult res)
-{
-    if (SLANG_SUCCEEDED(res))
-    {
-        return 0;
-    }
-    else if (res == SLANG_E_INTERNAL_FAIL)
-    {
-        return -1;
-    }
-    return 1;
-}
-
-void AppContext::setRequestWriters(SlangCompileRequest* request)
-{
-    for (int i = 0; i < SLANG_WRITER_CHANNEL_COUNT_OF; ++i)
-    {
-        if (m_replaceWriterFlags & (1 << i))
-        {
-            spSetWriter(request, SlangWriterChannel(i), m_writers[i]);
-        }
-    }
-}
-
-void AppContext::configureRequest(SlangCompileRequest* request)
-{
-    setRequestWriters(request);
-}
-
-}
-
diff --git a/source/core/slang-app-context.h b/source/core/slang-app-context.h
deleted file mode 100644
index 9f1eb306c..000000000
--- a/source/core/slang-app-context.h
+++ /dev/null
@@ -1,60 +0,0 @@
-#ifndef SLANG_APP_CONTEXT_H
-#define SLANG_APP_CONTEXT_H
-
-#include "slang-writer.h"
-#include "../../slang-com-ptr.h"
-
-namespace Slang
-{
-
-#ifdef SLANG_SHARED_LIBRARY_TOOL
-#   define SLANG_SHARED_LIBRARY_TOOL_API SLANG_EXTERN_C SLANG_DLL_EXPORT 
-#else
-#   define SLANG_SHARED_LIBRARY_TOOL_API
-#endif
-
-/* A structure to hold general state shared across an application */
-class AppContext
-{
-public:
-    
-    ISlangWriter * getWriter(SlangWriterChannel chan) const { return m_writers[chan]; }
-    void setWriter(SlangWriterChannel chan, ISlangWriter* writer) { m_writers[chan] = writer; }
-
-        /// Make modifications to the request
-    void configureRequest(SlangCompileRequest* request);
-
-    void setRequestWriters(SlangCompileRequest* request);
-
-    void setReplaceWriterFlagsAll() { setReplaceWriterFlags((1 << SLANG_WRITER_CHANNEL_COUNT_OF) - 1); }
-    void setReplaceWriterFlags(int flags) { m_replaceWriterFlags = flags;  }
-    int getReplaceWriterFlags() const { return m_replaceWriterFlags;  }
- 
-        /// Ctor
-    AppContext() : m_replaceWriterFlags(0) {}
-
-        /// Initialize a default context
-    static AppContext* initDefault();
-
-    static AppContext* getDefault();
-
-    static AppContext* getSingleton() { return s_singleton; }
-    static void setSingleton(AppContext* context) { s_singleton = context;  }
-
-    static WriterHelper getStdError() { return getSingleton()->getWriter(SLANG_WRITER_CHANNEL_STD_ERROR); }
-    static WriterHelper getStdOut() { return getSingleton()->getWriter(SLANG_WRITER_CHANNEL_STD_OUTPUT); }
-    static WriterHelper getDiagnostic() { return getSingleton()->getWriter(SLANG_WRITER_CHANNEL_DIAGNOSTIC); }
-
-    static int getReturnCode(SlangResult res);
-
-protected:
-
-    ComPtr<ISlangWriter> m_writers[SLANG_WRITER_CHANNEL_COUNT_OF]; 
-    int m_replaceWriterFlags;                                               ///< Bit for each writer
-
-    static AppContext* s_singleton;
-};
-
-}
-
-#endif
diff --git a/source/core/slang-std-writers.cpp b/source/core/slang-std-writers.cpp
new file mode 100644
index 000000000..963af9ef5
--- /dev/null
+++ b/source/core/slang-std-writers.cpp
@@ -0,0 +1,43 @@
+
+#include "slang-std-writers.h"
+
+namespace Slang
+{
+
+/* static */StdWriters* StdWriters::s_singleton = nullptr;
+
+/* static */StdWriters* StdWriters::getDefault()
+{
+    static StdWriters* s_context = nullptr;
+
+    if (!s_context)
+    {
+        static FileWriter s_stdError(stderr, WriterFlag::IsStatic | WriterFlag::IsUnowned | WriterFlag::AutoFlush);
+        static FileWriter s_stdOut(stdout, WriterFlag::IsStatic | WriterFlag::IsUnowned | WriterFlag::AutoFlush);
+
+        static StdWriters s_contextVar;
+        s_context = &s_contextVar;
+
+        s_context->setWriter(SLANG_WRITER_CHANNEL_STD_ERROR, &s_stdError);
+        s_context->setWriter(SLANG_WRITER_CHANNEL_STD_OUTPUT, &s_stdOut);
+    }
+    return s_context;
+}
+
+/* static */StdWriters* StdWriters::initDefault()
+{
+    StdWriters* context = getDefault();
+    setSingleton(context);
+    return context;
+}
+
+void StdWriters::setRequestWriters(SlangCompileRequest* request)
+{
+    for (int i = 0; i < SLANG_WRITER_CHANNEL_COUNT_OF; ++i)
+    {
+        spSetWriter(request, SlangWriterChannel(i), m_writers[i]);
+    }
+}
+
+}
+
diff --git a/source/core/slang-std-writers.h b/source/core/slang-std-writers.h
new file mode 100644
index 000000000..d580842eb
--- /dev/null
+++ b/source/core/slang-std-writers.h
@@ -0,0 +1,44 @@
+#ifndef SLANG_STD_WRITERS_H
+#define SLANG_STD_WRITERS_H
+
+#include "slang-writer.h"
+#include "../../slang-com-ptr.h"
+
+namespace Slang
+{
+
+/* Holds standard writers for the channels */
+class StdWriters
+{
+public:
+    ISlangWriter * getWriter(SlangWriterChannel chan) const { return m_writers[chan]; }
+    void setWriter(SlangWriterChannel chan, ISlangWriter* writer) { m_writers[chan] = writer; }
+
+        /// Set the writers on the SlangCompileRequest
+    void setRequestWriters(SlangCompileRequest* request);
+
+        /// Ctor
+    StdWriters() {}
+
+        /// Initialize a default context
+    static StdWriters* initDefault();
+
+    static StdWriters* getDefault();
+
+    static StdWriters* getSingleton() { return s_singleton; }
+    static void setSingleton(StdWriters* context) { s_singleton = context;  }
+
+    static WriterHelper getError() { return getSingleton()->getWriter(SLANG_WRITER_CHANNEL_STD_ERROR); }
+    static WriterHelper getOut() { return getSingleton()->getWriter(SLANG_WRITER_CHANNEL_STD_OUTPUT); }
+    static WriterHelper getDiagnostic() { return getSingleton()->getWriter(SLANG_WRITER_CHANNEL_DIAGNOSTIC); }
+
+protected:
+
+    ComPtr<ISlangWriter> m_writers[SLANG_WRITER_CHANNEL_COUNT_OF]; 
+    
+    static StdWriters* s_singleton;
+};
+
+}
+
+#endif
diff --git a/source/core/slang-test-tool-util.cpp b/source/core/slang-test-tool-util.cpp
new file mode 100644
index 000000000..7ecfacefa
--- /dev/null
+++ b/source/core/slang-test-tool-util.cpp
@@ -0,0 +1,21 @@
+
+#include "slang-test-tool-util.h"
+
+namespace Slang
+{
+
+/* static */int TestToolUtil::getReturnCode(SlangResult res)
+{
+    if (SLANG_SUCCEEDED(res))
+    {
+        return 0;
+    }
+    else if (res == SLANG_E_INTERNAL_FAIL)
+    {
+        return -1;
+    }
+    return 1;
+}
+
+}
+
diff --git a/source/core/slang-test-tool-util.h b/source/core/slang-test-tool-util.h
new file mode 100644
index 000000000..615bbe10d
--- /dev/null
+++ b/source/core/slang-test-tool-util.h
@@ -0,0 +1,25 @@
+#ifndef SLANG_TEST_TOOL_UTIL_H
+#define SLANG_TEST_TOOL_UTIL_H
+
+#include "slang-std-writers.h"
+
+namespace Slang {
+
+#ifdef SLANG_SHARED_LIBRARY_TOOL
+#   define SLANG_TEST_TOOL_API SLANG_EXTERN_C SLANG_DLL_EXPORT 
+#else
+#   define SLANG_TEST_TOOL_API
+#endif
+
+/* Utility functions for 'test tools' */
+struct TestToolUtil
+{
+    typedef SlangResult(*InnerMainFunc)(Slang::StdWriters* stdWriters, SlangSession* session, int argc, const char*const* argv);
+
+        /// Given a slang result, returns a return code that can be returned from an executable
+    static int getReturnCode(SlangResult res);
+};
+
+} // namespace Slang
+
+#endif // SLANG_TEST_TOOL_H
diff --git a/source/core/slang-writer.h b/source/core/slang-writer.h
index b18af373f..463450ac9 100644
--- a/source/core/slang-writer.h
+++ b/source/core/slang-writer.h
@@ -45,7 +45,7 @@ public:
     // ISlangUnknown
     SLANG_REF_OBJECT_IUNKNOWN_QUERY_INTERFACE
     SLANG_REF_OBJECT_IUNKNOWN_ADD_REF
-    SLANG_NO_THROW uint32_t SLANG_MCALL release() { return (m_flags & WriterFlag::IsStatic) ? 1 : (uint32_t)releaseReference(); }
+    SLANG_NO_THROW uint32_t SLANG_MCALL release() { return (m_flags & WriterFlag::IsStatic) ? (uint32_t)decreaseReference() : (uint32_t)releaseReference(); }
 
     // ISlangWriter - default impl
     SLANG_NO_THROW virtual void SLANG_MCALL flush() SLANG_OVERRIDE {}
diff --git a/source/slang/slang.vcxproj b/source/slang/slang.vcxproj
index a36d9bfbf..132a56ea5 100644
--- a/source/slang/slang.vcxproj
+++ b/source/slang/slang.vcxproj
@@ -314,4 +314,4 @@
   <Import Project="$(VCTargetsPath)\Microsoft.Cpp.targets" />
   <ImportGroup Label="ExtensionTargets">
   </ImportGroup>
-</Project> 
\ No newline at end of file
+</Project>
\ No newline at end of file
diff --git a/source/slangc/main.cpp b/source/slangc/main.cpp
index c2d64730a..ae15b7d49 100644
--- a/source/slangc/main.cpp
+++ b/source/slangc/main.cpp
@@ -5,8 +5,7 @@
 SLANG_API void spSetCommandLineCompilerMode(SlangCompileRequest* request);
 
 #include "../core/slang-io.h"
-#include "../core/slang-app-context.h"
-#include "../core/slang-writer.h"
+#include "../core/slang-test-tool-util.h"
 
 using namespace Slang;
 
@@ -16,7 +15,7 @@ static void diagnosticCallback(
     char const* message,
     void*       /*userData*/)
 {
-    auto stdError = AppContext::getStdError();
+    auto stdError = StdWriters::getError();
     stdError.put(message);
     stdError.flush();
 }
@@ -27,9 +26,9 @@ static void diagnosticCallback(
 #define MAIN main
 #endif
 
-SLANG_SHARED_LIBRARY_TOOL_API SlangResult innerMain(AppContext* appContext, SlangSession* session, int argc, const char*const* argv)
+SLANG_TEST_TOOL_API SlangResult innerMain(StdWriters* stdWriters, SlangSession* session, int argc, const char*const* argv)
 {
-    AppContext::setSingleton(appContext);
+    StdWriters::setSingleton(stdWriters);
 
     SlangCompileRequest* compileRequest = spCreateCompileRequest(session);
 
@@ -41,7 +40,7 @@ SLANG_SHARED_LIBRARY_TOOL_API SlangResult innerMain(AppContext* appContext, Slan
     spSetCommandLineCompilerMode(compileRequest);
 
     // Do any app specific configuration
-    appContext->configureRequest(compileRequest);
+    stdWriters->setRequestWriters(compileRequest);
 
     char const* appName = "slangc";
     if (argc > 0) appName = argv[0];
@@ -70,7 +69,7 @@ SLANG_SHARED_LIBRARY_TOOL_API SlangResult innerMain(AppContext* appContext, Slan
 #ifndef _DEBUG
     catch (Exception & e)
     {
-        AppContext::getStdOut().print("internal compiler error: %S\n", e.Message.ToWString().begin());
+        StdWriters::getOut().print("internal compiler error: %S\n", e.Message.ToWString().begin());
         res = SLANG_FAIL;
     }
 #endif
@@ -85,10 +84,10 @@ int MAIN(int argc, char** argv)
     SlangResult res;
     {
         SlangSession* session = spCreateSession(nullptr);
-        res = innerMain(AppContext::initDefault(), session, argc, argv);
+        res = innerMain(StdWriters::initDefault(), session, argc, argv);
         spDestroySession(session);
     }
-    return AppContext::getReturnCode(res);
+    return TestToolUtil::getReturnCode(res);
 }
 
 #ifdef _WIN32
diff --git a/tools/render-test/main.cpp b/tools/render-test/main.cpp
index dab8e9c6e..69874ac04 100644
--- a/tools/render-test/main.cpp
+++ b/tools/render-test/main.cpp
@@ -17,7 +17,7 @@
 #include <stdio.h>
 #include <stdlib.h>
 
-#include "../../source/core/slang-app-context.h"
+#include "../../source/core/slang-test-tool-util.h"
 
 #define WIN32_LEAN_AND_MEAN
 #define NOMINMAX
@@ -491,15 +491,15 @@ Result RenderTestApp::writeScreen(const char* filename)
 
 } //  namespace renderer_test
 
-SLANG_SHARED_LIBRARY_TOOL_API SlangResult innerMain(Slang::AppContext* appContext, SlangSession* session, int argcIn, const char*const* argvIn)
+SLANG_TEST_TOOL_API SlangResult innerMain(Slang::StdWriters* stdWriters, SlangSession* session, int argcIn, const char*const* argvIn)
 {
     using namespace renderer_test;
     using namespace Slang;
 
-    AppContext::setSingleton(appContext);
+    StdWriters::setSingleton(stdWriters);
 
 	// Parse command-line options
-	SLANG_RETURN_ON_FAIL(parseOptions(argcIn, argvIn, AppContext::getStdError()));
+	SLANG_RETURN_ON_FAIL(parseOptions(argcIn, argvIn, StdWriters::getError()));
 
     RefPtr<renderer_test::Window> window(new renderer_test::Window);
     SLANG_RETURN_ON_FAIL(window->initialize(gWindowWidth, gWindowHeight));
@@ -671,7 +671,7 @@ SLANG_SHARED_LIBRARY_TOOL_API SlangResult innerMain(Slang::AppContext* appContex
 int main(int argc, char**  argv)
 {
     SlangSession* session = spCreateSession(nullptr);
-    SlangResult res = innerMain(Slang::AppContext::initDefault(), session, argc, argv);
+    SlangResult res = innerMain(Slang::StdWriters::initDefault(), session, argc, argv);
     spDestroySession(session);
 
 	return SLANG_FAILED(res) ? 1 : 0;
diff --git a/tools/slang-reflection-test/main.cpp b/tools/slang-reflection-test/main.cpp
index ad474ee70..04818dfdf 100644
--- a/tools/slang-reflection-test/main.cpp
+++ b/tools/slang-reflection-test/main.cpp
@@ -8,7 +8,7 @@
 #include <slang.h>
 #include <slang-com-helper.h>
 
-#include "../../source/core/slang-app-context.h"
+#include "../../source/core/slang-test-tool-util.h"
 
 struct PrettyWriter
 {
@@ -19,7 +19,7 @@ struct PrettyWriter
 static void writeRaw(PrettyWriter& writer, char const* begin, char const* end)
 {
     SLANG_ASSERT(end >= begin);
-    Slang::AppContext::getStdOut().write(begin, size_t(end - begin));
+    Slang::StdWriters::getOut().write(begin, size_t(end - begin));
 }
 
 static void writeRaw(PrettyWriter& writer, char const* begin)
@@ -80,7 +80,7 @@ static void write(PrettyWriter& writer, char const* text)
 static void write(PrettyWriter& writer, SlangUInt val)
 {
     adjust(writer);
-    Slang::AppContext::getStdOut().print("%llu", (unsigned long long)val);
+    Slang::StdWriters::getOut().print("%llu", (unsigned long long)val);
 }
 
 static void emitReflectionVarInfoJSON(PrettyWriter& writer, slang::VariableReflection* var);
@@ -893,18 +893,18 @@ static SlangResult maybeDumpDiagnostic(SlangResult res, SlangCompileRequest* req
     const char* diagnostic;
     if (SLANG_FAILED(res) && (diagnostic = spGetDiagnosticOutput(request)))
     {
-        Slang::AppContext::getStdError().put(diagnostic);
+        Slang::StdWriters::getError().put(diagnostic);
     }
     return res;
 }
 
-SLANG_SHARED_LIBRARY_TOOL_API SlangResult innerMain(Slang::AppContext* appContext, SlangSession* session, int argc, const char*const* argv)
+SLANG_TEST_TOOL_API SlangResult innerMain(Slang::StdWriters* stdWriters, SlangSession* session, int argc, const char*const* argv)
 {
-    Slang::AppContext::setSingleton(appContext);
+    Slang::StdWriters::setSingleton(stdWriters);
     
     SlangCompileRequest* request = spCreateCompileRequest(session);
 
-    appContext->configureRequest(request);
+    stdWriters->setRequestWriters(request);
 
     char const* appName = "slang-reflection-test";
     if (argc > 0) appName = argv[0];
@@ -928,7 +928,7 @@ int main(
     char** argv)
 {
     SlangSession* session = spCreateSession(nullptr);
-    SlangResult res = innerMain(Slang::AppContext::initDefault(), session, argc, argv);
+    SlangResult res = innerMain(Slang::StdWriters::initDefault(), session, argc, argv);
     spDestroySession(session);
 
     return SLANG_FAILED(res) ? 1 : 0;
diff --git a/tools/slang-test/main.cpp b/tools/slang-test/main.cpp
index 07647e58f..102b0b961 100644
--- a/tools/slang-test/main.cpp
+++ b/tools/slang-test/main.cpp
@@ -2,7 +2,7 @@
 
 #include "../../source/core/slang-io.h"
 #include "../../source/core/token-reader.h"
-#include "../../source/core/slang-app-context.h"
+#include "../../source/core/slang-std-writers.h"
 
 #include "../../slang-com-helper.h"
 
@@ -386,16 +386,17 @@ OSError spawnAndWait(TestContext* context, const String& testPath, OSProcessSpaw
             StringWriter stdError(&stdErrorString, WriterFlag::IsConsole | WriterFlag::IsStatic);
             StringWriter stdOut(&stdOutString, WriterFlag::IsConsole | WriterFlag::IsStatic);
 
-            AppContext appContext;
-            appContext.setWriter(SLANG_WRITER_CHANNEL_STD_ERROR, &stdError);
-            appContext.setWriter(SLANG_WRITER_CHANNEL_STD_OUTPUT, &stdOut);
+            StdWriters* prevStdWriters = StdWriters::getSingleton();
+
+            StdWriters stdWriters;
+            stdWriters.setWriter(SLANG_WRITER_CHANNEL_STD_ERROR, &stdError);
+            stdWriters.setWriter(SLANG_WRITER_CHANNEL_STD_OUTPUT, &stdOut);
 
             if (exeName == "slangc")
             {
-                appContext.setWriter(SLANG_WRITER_CHANNEL_DIAGNOSTIC, &stdError);
+                stdWriters.setWriter(SLANG_WRITER_CHANNEL_DIAGNOSTIC, &stdError);
             }
-            appContext.setReplaceWriterFlagsAll();
-
+            
             List<const char*> args;
             args.Add(exeName.Buffer());
             for (int i = 0; i < int(spawner.argumentList_.Count()); ++i)
@@ -403,11 +404,14 @@ OSError spawnAndWait(TestContext* context, const String& testPath, OSProcessSpaw
                 args.Add(spawner.argumentList_[i].Buffer());
             }
 
-            SlangResult res = func(&appContext, context->getSession(), int(args.Count()), args.begin());
+            SlangResult res = func(&stdWriters, context->getSession(), int(args.Count()), args.begin());
+
+            StdWriters::setSingleton(prevStdWriters);
 
             spawner.standardError_ = stdErrorString;
             spawner.standardOutput_ = stdOutString;
-            spawner.resultCode_ = AppContext::getReturnCode(res);
+
+            spawner.resultCode_ = TestToolUtil::getReturnCode(res);
 
             return kOSError_None;
         }
@@ -1763,7 +1767,7 @@ void runTestsInDirectory(
 
 SlangResult innerMain(int argc, char** argv)
 {
-    AppContext::initDefault();
+    StdWriters::initDefault();
 
     // The context holds useful things used during testing
     TestContext context;
@@ -1789,7 +1793,7 @@ SlangResult innerMain(int argc, char** argv)
         context.setInnerMainFunc("slangc", &SlangCTool::innerMain);
     }
 
-    SLANG_RETURN_ON_FAIL(Options::parse(argc, argv, &categorySet, AppContext::getStdError(), &context.options));
+    SLANG_RETURN_ON_FAIL(Options::parse(argc, argv, &categorySet, StdWriters::getError(), &context.options));
     
     Options& options = context.options;
 
@@ -1799,7 +1803,7 @@ SlangResult innerMain(int argc, char** argv)
         auto func = context.getInnerMainFunc(options.binDir, options.subCommand);
         if (!func)
         {
-            AppContext::getStdError().print("error: Unable to launch tool '%s'\n", options.subCommand.Buffer());
+            StdWriters::getError().print("error: Unable to launch tool '%s'\n", options.subCommand.Buffer());
             return SLANG_FAIL;
         }
 
@@ -1812,7 +1816,7 @@ SlangResult innerMain(int argc, char** argv)
             args[i] = srcArgs[i].Buffer();
         }
 
-        return func(AppContext::getSingleton(), context.getSession(), int(args.Count()), args.Buffer());
+        return func(StdWriters::getSingleton(), context.getSession(), int(args.Count()), args.Buffer());
     }
 
     if( options.includeCategories.Count() == 0 )
diff --git a/tools/slang-test/options.cpp b/tools/slang-test/options.cpp
index 6f3f5d79b..0a6023733 100644
--- a/tools/slang-test/options.cpp
+++ b/tools/slang-test/options.cpp
@@ -37,7 +37,7 @@ TestCategory* TestCategorySet::findOrError(String const& name)
     TestCategory* category = find(name);
     if (!category)
     {
-        AppContext::getStdError().print("error: unknown test category name '%s'\n", name.Buffer());
+        StdWriters::getError().print("error: unknown test category name '%s'\n", name.Buffer());
     }
     return category;
 }
diff --git a/tools/slang-test/slangc-tool.cpp b/tools/slang-test/slangc-tool.cpp
index 3085e2ab5..bf1bb8c28 100644
--- a/tools/slang-test/slangc-tool.cpp
+++ b/tools/slang-test/slangc-tool.cpp
@@ -7,19 +7,19 @@ SLANG_API void spSetCommandLineCompilerMode(SlangCompileRequest* request);
 
 static void _diagnosticCallback(char const* message, void* /*userData*/)
 {
-    auto stdError = AppContext::getStdError();
+    auto stdError = StdWriters::getError();
     stdError.put(message);
     stdError.flush();
 }
 
-SlangResult SlangCTool::innerMain(AppContext* appContext, SlangSession* session, int argc, const char*const* argv)
+SlangResult SlangCTool::innerMain(StdWriters* stdWriters, SlangSession* session, int argc, const char*const* argv)
 {
     SlangCompileRequest* compileRequest = spCreateCompileRequest(session);
     spSetDiagnosticCallback(compileRequest, &_diagnosticCallback, nullptr);
 
     spSetCommandLineCompilerMode(compileRequest);
     // Do any app specific configuration
-    appContext->configureRequest(compileRequest);
+    stdWriters->setRequestWriters(compileRequest);
 
     {
         const SlangResult res = spProcessCommandLineArguments(compileRequest, &argv[1], argc - 1);
@@ -45,7 +45,7 @@ SlangResult SlangCTool::innerMain(AppContext* appContext, SlangSession* session,
 #ifndef _DEBUG
     catch (Exception & e)
     {
-        AppContext::getStdOut().print("internal compiler error: %S\n", e.Message.ToWString().begin());
+        StdWriters::getOut().print("internal compiler error: %S\n", e.Message.ToWString().begin());
         res = SLANG_FAIL;
     }
 #endif
diff --git a/tools/slang-test/slangc-tool.h b/tools/slang-test/slangc-tool.h
index dd6e1b977..a1fcaa71b 100644
--- a/tools/slang-test/slangc-tool.h
+++ b/tools/slang-test/slangc-tool.h
@@ -3,13 +3,13 @@
 #ifndef SLANGC_TOOL_H_INCLUDED
 #define SLANGC_TOOL_H_INCLUDED
 
-#include "../../source/core/slang-app-context.h"
+#include "../../source/core/slang-std-writers.h"
 
 /* The slangc 'tool' interface, such that slangc like functionality is available directly without invoking slangc command line tool, or
 need for a dll/shared library. */
 struct SlangCTool
 {
-    static SlangResult innerMain(Slang::AppContext* appContext, SlangSession* session, int argc, const char*const* argv);
+    static SlangResult innerMain(Slang::StdWriters* stdWriters, SlangSession* session, int argc, const char*const* argv);
 };
 
 #endif // SLANGC_TOOL_H_INCLUDED
diff --git a/tools/slang-test/test-context.h b/tools/slang-test/test-context.h
index cfa9837da..b07ca94e6 100644
--- a/tools/slang-test/test-context.h
+++ b/tools/slang-test/test-context.h
@@ -5,15 +5,18 @@
 
 #include "../../source/core/slang-string-util.h"
 #include "../../source/core/platform.h"
-#include "../../source/core/slang-app-context.h"
+#include "../../source/core/slang-std-writers.h"
 #include "../../source/core/dictionary.h"
+#include "../../source/core/slang-test-tool-util.h"
 
 #include "options.h"
 
 class TestContext
 {
     public:
-    typedef SlangResult(*InnerMainFunc)(Slang::AppContext* appContext, SlangSession* session, int argc, const char*const* argv);
+
+    typedef Slang::TestToolUtil::InnerMainFunc InnerMainFunc;
+
 
         /// Get the slang session
     SlangSession* getSession() const { return m_session;  }
diff --git a/tools/slang-test/test-reporter.h b/tools/slang-test/test-reporter.h
index 13bcfe6a4..38e0d2cc3 100644
--- a/tools/slang-test/test-reporter.h
+++ b/tools/slang-test/test-reporter.h
@@ -5,7 +5,7 @@
 
 #include "../../source/core/slang-string-util.h"
 #include "../../source/core/platform.h"
-#include "../../source/core/slang-app-context.h"
+#include "../../source/core/slang-std-writers.h"
 #include "../../source/core/dictionary.h"