kfl/README.md

## README.md

      
    Raw
  

              README.md
            
          
    Setup

You have some WASM code in fact.wat that you want to test.
You have installed the WebAssembly reference
interpreter,
and can call it as wasm (or <some_path>/wasm).
Writting and running tests

I like to write my tests in a separate file WAST, here
fact_test.wast, and keep my WAT files in pure WAT which can then be
processed with other tools.
The structure of my WAST scripts is typically to read in the WAT
file(s) under test with the input meta command (see the first line
of fact_test.wast), and then have a bunch of assert_return or
assert_trap assertions.
To run the tests use the command:
$ wasm fact_test.wast

Which will give no output if everything goes well. If you would
like to see that the computer is doing something, then you can ask the
interpreter to trace the execution with the -t flag:
$ wasm -t fact_test.wast
-- Running ("(input \"fact_test.wast\")")...
-- Parsing...
-- Running...
-- Loading (fact_test.wast)...
-- Parsing...
-- Running...
-- Loading (fact.wat)...
-- Parsing...
-- Running...
-- Checking...
-- Initializing...
-- Asserting return...
-- Invoking function "fact"...

Using WABT

If you for some reason would like to test with WABT (maybe your
teammates cannot compile the reference interpreter) then you have to
jump through a few hoops.
First, WABT does not understand the input meta-command. Fortunately,
the reference interpreter can help you:
$ wasm wasm fact_test.wast -o fact_test_for_wabt.wast

This will produce the file fact_test_for_wabt.wast where fact.wat
has been inlined. You can then use the wast2json from WABT to
produce the files fact_test_for_wabt.json and
fact_test_for_wabt.0.wasm (if you have multiple modules in your WAST
then there will be multiple .wasm files). Which you can then test
with the spectest-interp command:
$ spectest-interp fact_test_for_wabt.json
1/1 tests passed.

If you crave more output then use the -t flag to trace the execution.

  
## fact.wat
(module
 (export "fact" (func $fact))

 (func $fact (param $n i32) (result i32)
  (local $result i32)
  (local.set $result (i32.const 1))
  (if
   (local.get $n)
   (then (loop $start
     (local.set $result (i32.mul (local.get $n) (local.get $result)))
     (local.tee $n      (i32.sub (local.get $n) (i32.const 1)))
     (br_if $start))))
  (local.get $result)))

## fact_test.wast
(input "fact.wat")
(assert_return (invoke "fact" (i32.const 5)) (i32.const 120))
	(module
	(export "fact" (func $fact))

	(func $fact (param $n i32) (result i32)
	(local $result i32)
	(local.set $result (i32.const 1))
	(if
	(local.get $n)
	(then (loop $start
	(local.set $result (i32.mul (local.get $n) (local.get $result)))
	(local.tee $n (i32.sub (local.get $n) (i32.const 1)))
	(br_if $start))))
	(local.get $result)))
	(input "fact.wat")
	(assert_return (invoke "fact" (i32.const 5)) (i32.const 120))