Tests: fix detecting Python on systems with only "python3" command

test/cxx/Core/ApplicationPool/PoolTest.cpp

@@ -23,6 +23,7 @@ namespace tut {
 		Context context;
 		PoolPtr pool;
 		Pool::DebugSupportPtr debug;
+		string pythonCommand;
 		Ticket ticket;
 		GetCallback callback;
 		SessionPtr currentSession;
@@ -47,6 +48,7 @@ namespace tut {
 			context.finalize();
 			pool = boost::make_shared<Pool>(&context);
 			pool->initialize();
+			pythonCommand = findPythonCommand();
 			callback.func = _callback;
 			callback.userData = this;
 
@@ -113,6 +115,7 @@ namespace tut {
 			options.spawnMethod = "dummy";
 			options.appRoot = "stub/rack";
 			options.appType = "ruby";
+			options.python = pythonCommand.c_str();
 			options.appStartCommand = "ruby start.rb";
 			options.startupFile  = "start.rb";
 			options.loadShellEnvvars = false;

test/cxx/TestSupport.cpp

@@ -7,9 +7,11 @@
 #include <fcntl.h>
 #include <pwd.h>
 #include <grp.h>
-#include <cassert>
+#include <vector>
+#include <cstdlib>
 #include <FileTools/FileManip.h>
 #include <SystemTools/UserDatabase.h>
+#include <StrIntTools/StrIntUtils.h>
 #include <Utils/ScopeGuard.h>
 #include <jsoncpp/json.h>
 
@@ -36,6 +38,38 @@ createInstanceDir(InstanceDirectoryPtr &instanceDir) {
 	instanceDir = boost::make_shared<InstanceDirectory>(options);
 }
 
+string
+findCommandInPath(const string &basename) {
+	const char *path = getenv("PATH");
+	if (path == nullptr) {
+		return string();
+	}
+
+	vector<string> directories;
+	split(path, ':', directories);
+
+	for (const string &dir: directories) {
+		string fullPath = dir + "/" + basename;
+		if (fileExists(fullPath)) {
+			return fullPath;
+		}
+	}
+
+	return string();
+}
+
+string
+findPythonCommand() {
+	string python = findCommandInPath("python");
+	if (python.empty()) {
+		python = findCommandInPath("python3");
+	}
+	if (python.empty()) {
+		python = findCommandInPath("python2");
+	}
+	return python;
+}
+
 void
 writeUntilFull(int fd) {
 	int flags, ret;

test/cxx/TestSupport.h

@@ -106,6 +106,30 @@ extern Json::Value testConfig;
  */
 void createInstanceDir(InstanceDirectoryPtr &instanceDir);
 
+/**
+ * Find the given command in PATH. Returns the empty string if not found.
+ *
+ * @throws FileSystemException
+ * @throws TimeRetrievalException
+ * @throws boost::thread_interrupted
+ */
+string findCommandInPath(const string &basename);
+
+/**
+ * Find an appropriate Python command for this system, regardless of whether it's Python 2 or 3.
+ * Returns something like "/usr/bin/python3" if possible, but on older
+ * systems without Python 3 it could return something like "/usr/bin/python".
+ *
+ * This function primarily exists because newer systems don't have a "python" command anymore, only "python3".
+ *
+ * Returns the empty string if not found.
+ *
+ * @throws FileSystemException
+ * @throws TimeRetrievalException
+ * @throws boost::thread_interrupted
+ */
+string findPythonCommand();
+
 /**
  * Writes zeroes into the given file descriptor its buffer is full (i.e.
  * the next write will block).