diff --git a/RunCPM/parseopt_test.c b/RunCPM/parseopt_test.c
index 6672caa..589eeca 100644
--- a/RunCPM/parseopt_test.c
+++ b/RunCPM/parseopt_test.c
@@ -2,7 +2,113 @@
 #include "cheat.h"
 #include "parseoptions_testsetup.h"
 
+CHEAT_SET_UP(setupParseoptionsTest();)
 
 CHEAT_TEST(dummy,
   cheat_assert(1);
 )
+
+CHEAT_TEST(no_opts,
+  char *myargv[] = {"runcpm"};
+  _parse_options(1, myargv);
+  cheat_assert_not(streamInputActive);
+  cheat_assert(consoleOutputActive);
+  cheat_assert(streamInputFile == NULL);
+  cheat_assert(streamOutputFile == NULL);
+  cheat_assert_not(exit_value);
+  cheat_assert(cheat_compare(mystderr, ""));
+)
+
+CHEAT_TEST(dash_i,
+  char *myargv[] = {"runcpm", "-i", "inputfile"};
+  _parse_options(3, myargv);
+  cheat_assert(streamInputActive);
+  cheat_assert(consoleOutputActive);
+  cheat_assert(streamInputFile == myinfile);
+  cheat_assert(streamOutputFile == NULL);
+  cheat_assert(cheat_compare(infilename, "inputfile"));
+  cheat_assert(cheat_compare(outfilename, ""));
+  cheat_assert_not(exit_value);
+  cheat_assert(cheat_compare(mystderr, ""));
+)
+
+CHEAT_TEST(dash_o,
+  char *myargv[] = {"runcpm", "-o", "outputfile"};
+  _parse_options(3, myargv);
+  cheat_assert_not(streamInputActive);
+  cheat_assert(consoleOutputActive);
+  cheat_assert(streamInputFile == NULL);
+  cheat_assert(streamOutputFile == myoutfile);
+  cheat_assert(cheat_compare(infilename, ""));
+  cheat_assert(cheat_compare(outfilename, "outputfile"));
+  cheat_assert_not(exit_value);
+  cheat_assert(cheat_compare(mystderr, ""));
+)
+
+CHEAT_TEST(dash_i_o,
+  char *myargv[] = {"runcpm", "-i", "inputfile", "-o", "outputfile"};
+  _parse_options(5, myargv);
+  cheat_assert(streamInputActive);
+  cheat_assert(consoleOutputActive);
+  cheat_assert(streamInputFile == myinfile);
+  cheat_assert(streamOutputFile == myoutfile);
+  cheat_assert(cheat_compare(infilename, "inputfile"));
+  cheat_assert(cheat_compare(outfilename, "outputfile"));
+  cheat_assert_not(exit_value);
+  cheat_assert(cheat_compare(mystderr, ""));
+)
+
+CHEAT_TEST(dash_o_i,
+  char *myargv[] = {"runcpm", "-o", "outputfile", "-i", "inputfile"};
+  _parse_options(5, myargv);
+  cheat_assert(streamInputActive);
+  cheat_assert(consoleOutputActive);
+  cheat_assert(streamInputFile == myinfile);
+  cheat_assert(streamOutputFile == myoutfile);
+  cheat_assert(cheat_compare(infilename, "inputfile"));
+  cheat_assert(cheat_compare(outfilename, "outputfile"));
+  cheat_assert_not(exit_value);
+  cheat_assert(cheat_compare(mystderr, ""));
+)
+
+CHEAT_TEST(dash_s,
+  char *myargv[] = {"runcpm", "-s"};
+  _parse_options(2, myargv);
+  cheat_assert(streamInputActive);
+  cheat_assert_not(consoleOutputActive);
+  cheat_assert(streamInputFile == mystdin);
+  cheat_assert(streamOutputFile == mystdout);
+  cheat_assert(cheat_compare(infilename, ""));
+  cheat_assert(cheat_compare(outfilename, ""));
+  cheat_assert_not(exit_value);
+  cheat_assert(cheat_compare(mystderr, ""));
+)
+
+CHEAT_TEST(dash_i_no_ifile,
+  char *myargv[] = {"myruncpm", "-i"};
+  _parse_options(2, myargv);
+  cheat_assert(exit_value);
+  cheat_assert(strncmp(mystderr + 58, "usage: myruncpm", 15) == 0);
+)
+
+CHEAT_TEST(dash_o_no_ofile,
+  char *myargv[] = {"myruncpm", "-o"};
+  _parse_options(2, myargv);
+  cheat_assert(exit_value);
+  cheat_assert(strncmp(mystderr + 58, "usage: myruncpm", 15) == 0);
+)
+
+CHEAT_TEST(dash_i_o_no_ifile,
+  char *myargv[] = {"myruncpm", "-o", "outfile", "-i"};
+  _parse_options(4, myargv);
+  cheat_assert(exit_value);
+  cheat_assert(strncmp(mystderr + 58, "usage: myruncpm", 15) == 0);
+)
+
+CHEAT_TEST(dash_i_o_no_ofile,
+  char *myargv[] = {"myruncpm", "-i", "infile", "-o"};
+  _parse_options(4, myargv);
+  cheat_assert(exit_value);
+  cheat_assert(strncmp(mystderr + 58, "usage: myruncpm", 15) == 0);
+)
+
diff --git a/RunCPM/parseoptions_testsetup.c b/RunCPM/parseoptions_testsetup.c
index 2f253fd..736f107 100644
--- a/RunCPM/parseoptions_testsetup.c
+++ b/RunCPM/parseoptions_testsetup.c
@@ -11,6 +11,8 @@
 FILE mystdin[1];
 FILE mystdout[1];
 FILE mystderr[2000];
+FILE myinfile[1];
+FILE myoutfile[1];
 
 void myfprintf(FILE *out, const char *fmt, ...) {
   va_list va;
@@ -23,19 +25,16 @@ char infilename[50];
 char outfilename[50];
 char unknownfilename[50];
 
-void clearfilenames(void) {
-  *infilename = 0;
-  *outfilename = 0;
-  *unknownfilename = 0;
-}
-
 char *myfopen(const char *fname, const char *mode) {
   if (*mode == 'r') {
     strcpy(infilename, fname);
+    return myinfile;
   } else if (*mode == 'w') {
     strcpy(outfilename, fname);
+    return myoutfile;
   } else {
     strcpy(unknownfilename, fname);
+    return NULL;
   }
 }
 
@@ -67,4 +66,14 @@ void _file_failure_exit(char *argv[], char* fmt, char* filename)
 {
 }
 
+void setupParseoptionsTest(void) {
+  *infilename = 0;
+  *outfilename = 0;
+  *unknownfilename = 0;
+  streamInputFile = NULL;
+  streamOutputFile = NULL;
+  streamInputActive = FALSE;
+  consoleOutputActive = TRUE;
+}
+
 #include "parseoptions_vstudio.h"
diff --git a/RunCPM/parseoptions_testsetup.h b/RunCPM/parseoptions_testsetup.h
index b3d90f3..2c04b3f 100644
--- a/RunCPM/parseoptions_testsetup.h
+++ b/RunCPM/parseoptions_testsetup.h
@@ -5,6 +5,8 @@
 extern char mystdin[];
 extern char mystdout[];
 extern char mystderr[];
+extern char myinfile[];
+extern char myoutfile[];
 
 extern char infilename[];
 extern char outfilename[];
@@ -15,7 +17,9 @@ extern char	*streamOutputFile;
 extern char	streamInputActive;
 extern char	consoleOutputActive;
 
-void clearfilenames(void);
+extern int exit_value;
+
+void setupParseoptionsTest(void);
 
 void _usage(char *argv[]);
 
diff --git a/RunCPM/parseoptions_vstudio.h b/RunCPM/parseoptions_vstudio.h
index 8b28a1c..a67cd43 100644
--- a/RunCPM/parseoptions_vstudio.h
+++ b/RunCPM/parseoptions_vstudio.h
@@ -5,18 +5,15 @@ void _usage(char *argv[]) {
 		"usage: %s [-i input_file] [-o output_file] [-s]\n", argv[0]);
 	fprintf(stderr,
 		"  -i input_file: console input will be read from the file "
-		"with the\ngiven name. "
-		"After input file's EOF, further console input\nwill be read "
+		"with the\n     given name. "
+		"After input file's EOF, further console input\n     will be read "
 		"from the keyboard.\n");
 	fprintf(stderr,
 		"  -o output_file: console output will be written to the file "
-		"with the\ngiven name, in addition to the screen.\n");
+		"with the\n     given name, in addition to the screen.\n");
 	fprintf(stderr,
 		"  -s: console input and output is connected directly to "
-		"stdin and stdout.\nSince on Posix keyboard input is read from "
-		"stdin, switching from\nstdin to keyboard on stdin EOF is a "
-		"no-op. Therefore stdin EOF is an\nerror condition on Posix in "
-		"this case.\n");
+		"stdin and stdout.\n");
 }
 
 #define SET_OPTARG ++i; if (i >= argc) {++errflg; break;} optarg = argv[i];
@@ -24,7 +21,7 @@ void _usage(char *argv[]) {
 void _parse_options(int argc, char *argv[]) {
 	int errflg = 0;
 	char *optarg;
-	for (int i = 0; i < argc && errflg == 0; ++i) {
+	for (int i = 1; i < argc && errflg == 0; ++i) {
 		if (strcmp("-i", argv[i]) == 0) {
 			/* ++i;
 			if (i >= argc) {