mention that the str_copy return value does not include the \0

add unit test

str/str_copy.3

@@ -9,6 +9,6 @@ size_t \fBstr_copy\fP(char* \fIout\fR,const char* \fIin\fR);
 str_copy copies the leading bytes of \fIin\fR to \fIout\fR up to and
 including the first occurrance of \\0.
 
-str_copy returns the number of bytes copied.
+str_copy returns the number of bytes copied (not including the \\0).
 .SH "SEE ALSO"
 strlen(3)

str/str_copy.c

@@ -15,3 +15,13 @@ size_t str_copy(char *out,const char *in) {
   }
   return (size_t)(s-out);
 }
+
+#ifdef UNITTEST
+#include <assert.h>
+#include <string.h>
+
+int main() {
+  char buf[100];
+  memset(buf,1,sizeof(buf)); assert(str_copy(buf,"foo")==3 && !memcmp(buf,"foo",4));
+}
+#endif