Test 1: pbm grid : Should print 2224198737 25671 three times
2224198737 25671
2224198737 25671
2224198737 25671
Test 2: pbmnoise : Should print 0 0 0 0 : 0 four times
0 0 0 0 : 0
0 0 0 0 : 0
0 0 0 0 : 0
0 0 0 0 : 0
Test 3: pgm ellipse : Should print 0 0 0 0 0 : 0 four times
0 0 0 0 0 : 0
0 0 0 0 0 : 0
0 0 0 0 0 : 0
0 0 0 0 0 : 0
Test 4: pgm ellipse -4depth : Should print 0 0 0 0 0 : 0 three times
0 0 0 0 0 : 0
0 0 0 0 0 : 0
0 0 0 0 0 : 0