Adds tests for SIO statement and SERR() function.

This needs newer version of mini65 emulator, using an emulated disk
drive to write and read sectors.

Author: dmsc

testsuite/mini65

@@ -0,0 +1,39 @@
+' Test SIO statement
+? "Start"
+DIM buf1(128) byte, buf2(128) byte
+' Write some data into buffer
+FOR i=0 TO 128 : buf1(i)=255-i : NEXT
+
+' Try reading buf1 from sector 0 (invalid)
+SIO $31, 1, $52, 64, &buf1, 15, 128, 0, 0
+? SERR()
+' Write buf1 to emulated sector 719
+SIO $31, 1, $50, 128, &buf1, 15, 128, 719 & 255, 719/256
+? SERR()
+' Write buf2 to emulated sector 720
+SIO $31, 1, $50, 128, &buf2, 15, 128, 720 & 255, 720/256
+? SERR()
+' Read buf2 from emulated sector 719
+SIO $31, 1, $52, 64, &buf2, 15, 128, 719 & 255, 719/256
+? SERR()
+' Read buf1 from emulated sector 720
+SIO $31, 1, $52, 64, &buf1, 15, 128, 720 & 255, 720/256
+? SERR()
+
+' Check values of buf1
+? "1:";
+FOR i=0 TO 127
+    If buf1(i) <> 0
+        ? " "; i; "="; buf1(i);
+    Endif
+NEXT
+?
+
+' Check values of buf2
+? "2:";
+FOR i=0 TO 127
+    If buf2(i) <> 255-i
+        ? " "; i; "="; buf2(i);
+    Endif
+NEXT
+?

testsuite/tests/stmt-sio.bas

@@ -0,0 +1,11 @@
+Name: Test SIO statement
+Test: run
+Output:
+Start
+139
+1
+1
+1
+1
+1:
+2: