Simple test of -D cmd-line parameter

testdata/scad/misc/override.scad

@@ -0,0 +1,4 @@
+// Used to test variable override with the -D parameter
+a = 1;
+b = 2;
+echo(a,b);

tests/CMakeLists.txt

@@ -1010,7 +1010,16 @@ add_cmdline_test(openscad-nonascii EXE ${OPENSCAD_BINPATH} ARGS -o
                  FILES ${CMAKE_SOURCE_DIR}/../testdata/scad/misc/sfære.scad)
 
 
-# Image output
+# Variable override (-D arg)
+
+# Override simple variable
+add_cmdline_test(openscad-override EXE ${OPENSCAD_BINPATH}
+                 ARGS -D a=3$<SEMICOLON> -o
+                 SUFFIX echo
+                 FILES ${CMAKE_SOURCE_DIR}/../testdata/scad/misc/override.scad)
+
+
+# Image output parameters
 add_cmdline_test(openscad-imgsize EXE ${OPENSCAD_BINPATH}
                  ARGS --imgsize 100,100 -o 
                  SUFFIX png 

tests/regression/openscad-override/override-expected.echo

@@ -0,0 +1 @@
+ECHO: 3, 2