Add directory for I/O tests with basic test for file methods.

tests/io/data/file1

@@ -0,0 +1,3 @@
+longer line1
+line2
+line3

tests/io/file1.py

@@ -0,0 +1,4 @@
+f = open("io/data/file1")
+print(f.read(5))
+print(f.readline())
+print(f.read())

tests/run-tests

@@ -10,7 +10,7 @@ numpassed=0
 numfailed=0
 namefailed=
 
-for infile in basics/*.py
+for infile in basics/*.py io/*.py
 do
     basename=`basename $infile .py`
     outfile=${basename}.out