test: StreamCapture on pipes

Enhance StreamCapture class to mimic gtest's CaptureStdout/Stderr functionality.
Store data in a pipe instead of a temporary file like gtest
resulting in faster test execution

Signed-off-by: Marcel Skierkowski <marcel.skierkowski@intel.com>

shared/test/common/helpers/stream_capture.h

@@ -20,29 +20,46 @@
 #include <unistd.h>
 #endif
 
-class StdoutCapture {
+class StreamCapture {
   public:
     void captureStdout() {
+        captureStream(stdout, pipefdStdout, saveStdout);
+    }
+
+    void captureStderr() {
+        captureStream(stderr, pipefdStderr, saveStderr);
+    }
+
+    std::string getCapturedStdout() {
+        return getCapturedStream(stdout, pipefdStdout, saveStdout);
+    }
+
+    std::string getCapturedStderr() {
+        return getCapturedStream(stderr, pipefdStderr, saveStderr);
+    }
+
+  private:
+    void captureStream(FILE *stream, int pipefd[2], int &savedFd) {
 #ifdef _WIN32
         _pipe(pipefd, 4096, O_TEXT);
-        fflush(stdout);
-        saveStdout = _dup(_fileno(stdout));
-        _dup2(pipefd[1], _fileno(stdout));
+        fflush(stream);
+        savedFd = _dup(_fileno(stream));
+        _dup2(pipefd[1], _fileno(stream));
         _close(pipefd[1]);
 #else
-        fflush(stdout);
+        fflush(stream);
         pipe(pipefd);
-        saveStdout = dup(fileno(stdout));
-        dup2(pipefd[1], fileno(stdout));
+        savedFd = dup(fileno(stream));
+        dup2(pipefd[1], fileno(stream));
         close(pipefd[1]);
 #endif
     }
 
-    std::string getCapturedStdout() {
+    std::string getCapturedStream(FILE *stream, int pipefd[2], int &savedFd) {
 #ifdef _WIN32
-        fflush(stdout);
-        _dup2(saveStdout, _fileno(stdout));
-        _close(saveStdout);
+        fflush(stream);
+        _dup2(savedFd, _fileno(stream));
+        _close(savedFd);
 
         char buffer[4096];
         int count = _read(pipefd[0], buffer, sizeof(buffer) - 1);
@@ -52,9 +69,9 @@ class StdoutCapture {
         }
         return "";
 #else
-        fflush(stdout);
-        dup2(saveStdout, fileno(stdout));
-        close(saveStdout);
+        fflush(stream);
+        dup2(savedFd, fileno(stream));
+        close(savedFd);
 
         constexpr size_t bufferSize = 4096;
         char buffer[bufferSize];
@@ -67,7 +84,8 @@ class StdoutCapture {
 #endif
     }
 
-  private:
-    int pipefd[2];
+    int pipefdStdout[2];
+    int pipefdStderr[2];
     int saveStdout;
-};
+    int saveStderr;
+};