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{-|
Module : Test.Core.Termination
Description : Tests for termination checking (Agent 4B)
-}
module Test.Core.Termination
( tests
) where
import Test.Tasty
import Test.Tasty.HUnit
import qualified Data.Text as T
import Assertica.Core.AST
import Assertica.Core.Termination
import Assertica.Core.TypeEnv
-- ============================================================================
-- TEST SUITE
-- ============================================================================
tests :: TestTree
tests = testGroup "Assertica.Core.Termination"
[ testGroup "Recursion Detection"
[ testCase "No recursion detected in simple term" testNoRecursion
, testCase "Direct recursion detected" testDirectRecursion
, testCase "Recursion in application" testRecursionInApp
, testCase "Recursion in case expression" testRecursionInCase
]
, testGroup "Simple Recursion Patterns"
[ testCase "Simple structural recursion accepted" testStructuralRecursion
, testCase "Non-terminating recursion rejected" testNonTerminating
, testCase "Guarded recursion accepted" testGuardedRecursion
]
, testGroup "Recursive Call Analysis"
[ testCase "Find direct recursive call" testFindDirectCall
, testCase "Analyze structural call pattern" testStructuralCallPattern
, testCase "Detect unsupported recursion pattern" testUnsupportedPattern
]
, testGroup "Mutual Recursion"
[ testCase "Mutual recursion with progress" testMutualRecursionProgress
, testCase "Infinite mutual recursion rejected" testInfiniteMutualRecursion
, testCase "Call cycle detection" testCallCycleDetection
]
, testGroup "Integration Tests"
[ testCase "Length function on List" testLengthFunction
, testCase "Fibonacci with guards" testFibonacciFunction
, testCase "Map over list" testMapFunction
]
, testGroup "Error Messages"
[ testCase "Non-terminating error message" testNonTerminatingError
, testCase "Unsupported pattern error message" testUnsupportedPatternError
, testCase "Cycle detection error message" testCycleDetectionError
]
]
-- ============================================================================
-- HELPER FUNCTIONS
-- ============================================================================
{-| Create a simple variable. -}
var :: Text -> Var
var name = Var name 0
{-| Create a simple qualified name. -}
qn :: Text -> QName
qn name = QName [] name
{-| Create a binder. -}
binder :: Text -> Maybe Type -> Binder
binder name mty = Binder (var name) mty
{-| Create a pattern for a variable. -}
patVar :: Text -> Pattern
patVar name = PatVar (var name)
{-| Create a clause. -}
clause :: Pattern -> Term -> Clause
clause = Clause
-- ============================================================================
-- RECURSION DETECTION TESTS
-- ============================================================================
testNoRecursion :: Assertion
testNoRecursion = do
-- A simple non-recursive term
let term = Const (IntLit 42)
assertBool "Non-recursive term should not have recursion" $
not (hasRecursion term)
testDirectRecursion :: Assertion
testDirectRecursion = do
-- A term that calls itself: f x
let term = App (Var (var "f")) (Var (var "x"))
assertBool "Application of f should be detected as having recursion" $
hasRecursion term
testRecursionInApp :: Assertion
testRecursionInApp = do
-- f (g x)
let term = App (Var (var "f")) (App (Var (var "g")) (Var (var "x")))
assertBool "Recursion in nested application should be detected" $
hasRecursion term
testRecursionInCase :: Assertion
testRecursionInCase = do
-- case x of P -> f y
let scrutinee = Var (var "x")
c1 = clause (patVar "y") (App (Var (var "f")) (Var (var "y")))
term = Case scrutinee [c1] Nothing
assertBool "Recursion in case body should be detected" $
hasRecursion term
-- ============================================================================
-- SIMPLE RECURSION PATTERN TESTS
-- ============================================================================
testStructuralRecursion :: Assertion
testStructuralRecursion = do
-- length (Cons h t) = 1 + length t
-- Simplified: just the recursive call part
let funcName = "length"
-- App of length to a term
term = App (Var (var "length")) (Var (var "t"))
case checkTermination emptyEnv funcName term of
Right () -> return () -- Should succeed
Left err -> assertFailure $ "Structural recursion should pass: " ++ prettyTermError err
testNonTerminating :: Assertion
testNonTerminating = do
-- f x = f (x + 1)
let funcName = "f"
-- The recursive call f (x + 1)
successor = App (Const (PrimOp OpAdd)) (Var (var "x"))
term = App (Var (var "f")) successor
case checkTermination emptyEnv funcName term of
Left (NonTerminatingRecursion _) -> return () -- Should fail
Left err -> assertFailure $ "Wrong error type: " ++ show err
Right () -> assertFailure "Non-terminating recursion should be rejected"
testGuardedRecursion :: Assertion
testGuardedRecursion = do
-- Simplified guarded recursion
let funcName = "countdown"
-- countdown n = if n <= 0 then ... else countdown (n - 1)
-- Just the recursive part
term = App (Var (var "countdown")) (Var (var "n"))
case checkTermination emptyEnv funcName term of
Right () -> return () -- Should succeed (structural pattern)
Left err -> assertFailure $ "Guarded recursion should pass: " ++ prettyTermError err
-- ============================================================================
-- RECURSIVE CALL ANALYSIS TESTS
-- ============================================================================
testFindDirectCall :: Assertion
testFindDirectCall = do
let funcName = "length"
term = App (Var (var "length")) (Var (var "t"))
case analyzeRecursiveCalls funcName term of
Right calls ->
case calls of
[RecursiveCall name _ _] ->
assertEqual "Should find call to length" name "length"
[] -> assertFailure "Should find at least one recursive call"
_ -> assertFailure "Should find exactly one recursive call"
Left err -> assertFailure $ "Analysis should succeed: " ++ prettyTermError err
testStructuralCallPattern :: Assertion
testStructuralCallPattern = do
let funcName = "walk"
-- walk (tree)
term = App (Var (var "walk")) (Constr (qn "Leaf") [Var (var "x")])
case analyzeRecursiveCalls funcName term of
Right [RecursiveCall _ pattern _] ->
assertEqual "Should detect structural call pattern" pattern (StructuralCall "constr")
_ -> assertFailure "Should find structural call pattern"
testUnsupportedPattern :: Assertion
testUnsupportedPattern = do
let funcName = "strange"
-- A recursive call with unknown pattern
unhandledOp = App (Const (PrimOp OpDiv)) (Var (var "x"))
term = App (Var (var "strange")) unhandledOp
case analyzeRecursiveCalls funcName term of
Right calls ->
case calls of
[RecursiveCall _ UnknownPattern _] -> return ()
_ -> assertFailure "Should detect unknown pattern"
Left err -> assertFailure $ "Analysis should still work: " ++ prettyTermError err
-- ============================================================================
-- MUTUAL RECURSION TESTS
-- ============================================================================
testMutualRecursionProgress :: Assertion
testMutualRecursionProgress = do
-- even n = if n == 0 then true else odd (n - 1)
-- odd n = if n == 0 then false else even (n - 1)
let functions = [("even", Var (var "x")), ("odd", Var (var "y"))]
case checkTerminationMulti emptyEnv functions of
Right () -> return () -- Should succeed
Left err -> assertFailure $ "Mutual recursion with progress should pass: " ++ prettyTermError err
testInfiniteMutualRecursion :: Assertion
testInfiniteMutualRecursion = do
-- f x = g x
-- g x = f x
-- No progress on any argument
let functions = [("f", Var (var "x")), ("g", Var (var "x"))]
case checkTerminationMulti emptyEnv functions of
Left (InfiniteCallCycle _) -> return () -- Should detect cycle
Left err -> assertFailure $ "Wrong error type: " ++ show err
Right () -> assertFailure "Infinite cycle should be rejected"
testCallCycleDetection :: Assertion
testCallCycleDetection = do
-- a calls b, b calls c, c calls a
let functions = [("a", Var (var "b")), ("b", Var (var "c")), ("c", Var (var "a"))]
case checkTerminationMulti emptyEnv functions of
Left (InfiniteCallCycle cycle_path) ->
assertBool "Cycle should be detected" (length cycle_path > 0)
_ -> assertFailure "Should detect cycle in call graph"
-- ============================================================================
-- INTEGRATION TESTS
-- ============================================================================
testLengthFunction :: Assertion
testLengthFunction = do
-- Simulate length :: List a -> Nat
-- length Nil = 0
-- length (Cons _ t) = 1 + length t
let funcName = "length"
-- The recursive case: length t
consCase = Constr (qn "Cons") [Var (var "h"), Var (var "t")]
recursiveCall = App (Var (var "length")) (Var (var "t"))
case checkTermination emptyEnv funcName recursiveCall of
Right () -> return ()
Left err -> assertFailure $ "length should terminate: " ++ prettyTermError err
testFibonacciFunction :: Assertion
testFibonacciFunction = do
-- fib n = if n <= 1 then n else fib(n-1) + fib(n-2)
-- For simplicity, just check the recursive call part
let funcName = "fib"
-- fib (n - 1)
term = App (Var (var "fib")) (Var (var "n"))
case checkTermination emptyEnv funcName term of
Right () -> return ()
Left err -> assertFailure $ "fib should pass initial check: " ++ prettyTermError err
testMapFunction :: Assertion
testMapFunction = do
-- map :: (a -> b) -> List a -> List b
-- map f [] = []
-- map f (x:xs) = f x : map f xs
let funcName = "map"
-- map f xs
recursiveCall = App (Var (var "map")) (Var (var "xs"))
case checkTermination emptyEnv funcName recursiveCall of
Right () -> return ()
Left err -> assertFailure $ "map should terminate: " ++ prettyTermError err
-- ============================================================================
-- ERROR MESSAGE TESTS
-- ============================================================================
testNonTerminatingError :: Assertion
testNonTerminatingError = do
let err = NonTerminatingRecursion "recursive call does not decrease"
let msg = prettyTermError err
assertBool "Error message should mention non-termination" $
"does not terminate" `elem` words msg
testUnsupportedPatternError :: Assertion
testUnsupportedPatternError = do
let err = UnsupportedRecursionPattern "unknown pattern found"
let msg = prettyTermError err
assertBool "Error message should mention unsupported pattern" $
"pattern" `elem` words msg
testCycleDetectionError :: Assertion
testCycleDetectionError = do
let cycle_path = ["f", "g", "f"]
let err = InfiniteCallCycle cycle_path
let msg = prettyTermError err
assertBool "Error message should mention cycle" $
"cycle" `elem` words msg
|