( Basic Forth test suite )

testing "Basic stack operations"
5 dup . . test 5 test 5

testing "Addition"
3 4 + test 7

testing "Subtraction"
10 3 - test 7

testing "Multiplication"
6 7 * test 42

testing "Division"
20 4 / test 5

testing "Stack manipulation - rot"
1 2 3 rot test 1

testing "Stack manipulation - drop"
1 2 3 drop test 2

testing "Stack manipulation - nip"
1 2 3 nip test 3

testing "Stack manipulation - tuck"
1 2 tuck test 2

testing "Stack manipulation - over"
1 2 over test 1

testing "Variables"
variable x
5 x !
x @ test 5
10 x !
x ? ( should print 10 )

testing "Negate"
5 negate test -5

testing "Absolute value"
-7 abs test 7

testing "Maximum"
3 8 max test 8

testing "Minimum"
3 8 min test 3

testing "Modulo"
17 5 mod test 2

testing "Equality"
5 5 = test 1
5 6 = test 0

testing "Word definition"
: square dup * ;
5 square test 25

testing "Complex word definition"
variable counter
: increment-counter counter @ 1 + counter ! ;
5 counter !
increment-counter
counter @ test 6

testing "Basic conditional - if/then"
: test-if-1 ( n -- n ) dup 5 > if ." Greater than 5" then ;
6 test-if-1 test 6 ( should print "Greater than 5" and leave 6 )
4 test-if-1 test 4 ( should print nothing and leave 4 )

testing "Basic conditional - if/else/then"
: test-if-2 ( n -- n ) dup 5 > if ." Greater" else ." Less=" then ;
6 test-if-2 test 6 ( should print "Greater" and leave 6 )
4 test-if-2 test 4 ( should print "Less=" and leave 4 )
5 test-if-2 test 5 ( should print "Less=" and leave 5 )

testing "Nested conditionals"
: test-if-3 ( n -- n ) 
    dup 10 > if 
        dup 20 > if 
            ." >20 "
        then
        ." >10 "
    then ;
25 test-if-3 test 25 ( should print ">20 >10 " and leave 25 )
15 test-if-3 test 15 ( should print ">10 " and leave 15 )
5 test-if-3 test 5   ( should print nothing and leave 5 )

testing "Conditional with stack operations"
: test-if-4 ( n -- n n ) 
    dup 5 > if 
        dup 
    then ;
6 test-if-4 swap test 6 test 6 ( should leave 6 6 )
4 test-if-4 test 4 ( should leave just 4 )

testing "Complex nested conditionals"
: test-if-5 ( n -- n )
    dup 0 < if
        ." negative "
    else
        dup 100 > if
            ." big "
        else 
            dup 50 > if
                ." medium "
            else
                ." small "
            then
        then
    then ;
-5 test-if-5 test -5 ( should print "negative " )
150 test-if-5 test 150 ( should print "big " )
75 test-if-5 test 75 ( should print "medium " )
25 test-if-5 test 25 ( should print "small " )

testing "Conditionals in word definitions"
: abs-test ( n -- |n| ) dup 0 < if negate then ;
-5 abs-test test 5
5 abs-test test 5

testing "Complex conditional word"
: max-test ( n1 n2 -- max ) 
    2dup > if 
        drop 
    else 
        nip 
    then ;
5 3 max-test test 5
3 5 max-test test 5

( Try to use if outside of a definition - should error )
testing "Compile-only words"
5 4 > if 42 then ( should print error about compile-only word )

testing "Comparison operators"
5 3 > test 1  ( 5 > 3 is true )
3 5 > test 0  ( 3 > 5 is false )
3 5 < test 1  ( 3 < 5 is true )
5 3 < test 0  ( 5 < 3 is false )
5 5 < test 0  ( 5 < 5 is false )
5 5 > test 0  ( 5 > 5 is false )

testing "Comparison in conditionals"
: test-compare ( n -- )
dup 5 > if ." Greater than 5" else
dup 5 < if ." Less than 5" else
." Equal to 5" then then ;
6 test-compare ( should print "Greater than 5" )
4 test-compare ( should print "Less than 5" )
5 test-compare ( should print "Equal to 5" )

bye