testing: support for internal module testing

vlib/compiler/tests/modules/amodule/another_internal_module_test.v

@@ -0,0 +1,16 @@
+module amodule
+
+// This tests whether _test.v files can be *internal* to a 
+// module, and thus have access to its guts.
+
+// NB: the function test_private_isub() is defined both here
+// and inside internal_module_test.v . That is done on purpose, 
+// with the goal of ensuring that _test.v files are compiled 
+// *independently* from each other.
+//
+// _test.v files should *only* import all the other normal .v 
+// files from the same folder, NOT other _test.v files from it.
+
+fn test_private_isub(){
+  assert private_isub(7,5) == 2
+}

vlib/compiler/tests/modules/amodule/internal_module_test.v

@@ -0,0 +1,16 @@
+module amodule
+
+// this tests whether _test.v files can be *internal* 
+// to a module, and thus have access to its guts.
+
+fn test_iadd(){
+	assert iadd(10, 20) == 30
+}
+
+fn test_imul(){
+	assert imul(5,8) == 40
+}
+
+fn test_private_isub(){
+  assert private_isub(10,6) == 4
+}

vlib/compiler/tests/modules/amodule/module.v

@@ -0,0 +1,15 @@
+module amodule
+
+pub fn iadd(x int, y int) int {
+	return x + y
+}
+
+pub fn imul(x int, y int) int {
+	return x * y
+}
+
+///////////////////////////////////////
+
+fn private_isub(x int, y int) int {
+  return x - y
+}