Ensure apischema round-trips all test suite cases

[klauer]

Goal

• All blark dataclasses from blark.transform should be able to be converted to JSON by way of apischema.serialize
• All generated JSON should similarly be able to be transformed back to dataclasses by way of apischema.deserialize
• apischema should remain an optional dependency of blark

"JSON" above refers to JSON-serializable data types, including Python built-ins such as dicts, lists, ints, floats, and strings. The conversion of that to an actual serialized JSON string is an additional step.

Issue

During the course of testing, I ran into some issues with apischema on Python 3.9+ (at least according to inline code comments). I wasn't able to get to the heart of the issue to determine a path forward, I merely set up a "skip if on Python 3.9+ or apischema is unavailable".

Test suite reference:

blark/blark/tests/test_transformer.py

Lines 19 to 21 in 263e263

	# TODO: apischema serialization is recursing infinitely on 3.9 and 3.10;
	# need to dig into details and report it (first test that fails is ARRAY-related)
	APISCHEMA_SKIP = sys.version_info[:2] >= (3, 9)

Optional dependency in the transformer dataclass section:

blark/blark/transform.py

Lines 18 to 28 in 263e263

	try:
	# NOTE: apischema is an optional requirement; this should work regardless.
	import apischema
	from .apischema_compat import as_tagged_union
	except ImportError:
	apischema = None
	def as_tagged_union(cls: Type[T]) -> Type[T]:
	"""No-operation stand-in for when apischema is not available."""
	return cls

Failing tests as of 263e263

With APISCHEMA_SKIP set to False on Python 3.9 and blark 263e263, the following tests fail on the serialization portion (at least sometimes due to a recursion error in apischema). apischema=0.17.5, 84 failed, 144 passed, 5 xfailed in 77.86s (0:01:17)

FAILED tests/test_transformer.py::test_expression_roundtrip[array_type_declaration-TypeName : ARRAY [1..2, 3..4] OF INT] - Re...
FAILED tests/test_transformer.py::test_expression_roundtrip[array_type_declaration-TypeName : ARRAY [1..2] OF INT := [1, 2]]
FAILED tests/test_transformer.py::test_expression_roundtrip[array_type_declaration-TypeName : ARRAY [1..2, 3..4] OF INT := [2(3), 3(4)]]
FAILED tests/test_transformer.py::test_expression_roundtrip[array_type_declaration-TypeName : ARRAY [1..2, 3..4] OF Tc.SomeType]
FAILED tests/test_transformer.py::test_expression_roundtrip[structure_type_declaration-TypeName :\nSTRUCT\nEND_STRUCT] - Recu...
FAILED tests/test_transformer.py::test_expression_roundtrip[structure_type_declaration-TypeName EXTENDS Other.Type :\nSTRUCT\nEND_STRUCT]
FAILED tests/test_transformer.py::test_expression_roundtrip[structure_type_declaration-TypeName : POINTER TO\nSTRUCT\nEND_STRUCT]
FAILED tests/test_transformer.py::test_expression_roundtrip[structure_type_declaration-TypeName : POINTER TO\nSTRUCT\n    iValue : INT;\nEND_STRUCT]
FAILED tests/test_transformer.py::test_expression_roundtrip[structure_type_declaration-TypeName : POINTER TO\nSTRUCT\n    iValue : INT := 3 + 4;\n    stTest : ST_Testing := (1, 2);\n    eValue : E_Test := E_Test.ABC;\n    arrValue : ARRAY [1..2] OF INT := [1, 2];\n    arrValue1 : INT (1..2);\n    arrValue1 : (Value1 := 1) INT;\n    sValue : STRING := 'abc';\n    iValue1 AT %I* : INT := 5;\n    iValue2 AT %Q* : INT := 5;\n    iValue3 AT %M* : INT := 5;\n    sValue1 : STRING[10] := 'test';\nEND_STRUCT]
FAILED tests/test_transformer.py::test_input_roundtrip[input_declarations-VAR_INPUT\nEND_VAR] - RecursionError: maximum recur...
FAILED tests/test_transformer.py::test_input_roundtrip[input_declarations-VAR_INPUT RETAIN\nEND_VAR] - RecursionError: maximu...
FAILED tests/test_transformer.py::test_input_roundtrip[input_declarations-VAR_INPUT RETAIN\n    iValue : INT;\n    sValue : STRING := 'abc';\n    wsValue : WSTRING := "abc";\nEND_VAR]
FAILED tests/test_transformer.py::test_input_roundtrip[input_declarations-VAR_INPUT RETAIN\n    iValue : INT;\n    sValue : STRING := 'abc';\n    wsValue : WSTRING := "abc";\n    fbTest : FB_Test(1, 2, 3);\n    fbTest : FB_Test(A := 1, B := 2, C => 3);\n    fbTest : FB_Test(1, 2, A := 1, B := 2, C => 3);\n    fbTest : FB_Test := (1, 2, 3);\nEND_VAR]
FAILED tests/test_transformer.py::test_output_roundtrip[output_declarations-VAR_OUTPUT\nEND_VAR] - RecursionError: maximum re...
FAILED tests/test_transformer.py::test_output_roundtrip[output_declarations-VAR_OUTPUT RETAIN\nEND_VAR] - RecursionError: max...
FAILED tests/test_transformer.py::test_output_roundtrip[output_declarations-VAR_OUTPUT RETAIN\n    iValue : INT;\n    sValue : STRING := 'abc';\n    wsValue : WSTRING := "abc";\nEND_VAR]
FAILED tests/test_transformer.py::test_output_roundtrip[output_declarations-VAR_OUTPUT RETAIN\n    iValue : INT;\n    sValue : STRING := 'abc';\n    wsValue : WSTRING := "abc";\n    fbTest : FB_Test(1, 2, 3);\n    fbTest : FB_Test(A := 1, B := 2, C => 3);\n    fbTest : FB_Test(1, 2, A := 1, B := 2, C => 3);\n    fbTest : FB_Test := (1, 2, 3);\nEND_VAR]
FAILED tests/test_transformer.py::test_input_output_roundtrip[input_output_declarations-VAR_IN_OUT\nEND_VAR] - RecursionError...
FAILED tests/test_transformer.py::test_input_output_roundtrip[input_output_declarations-VAR_IN_OUT\n    iValue : INT;\n    sValue : STRING := 'abc';\n    wsValue : WSTRING := "abc";\nEND_VAR]
FAILED tests/test_transformer.py::test_input_output_roundtrip[input_output_declarations-VAR_IN_OUT\n    iValue : INT;\n    sValue : STRING := 'abc';\n    wsValue : WSTRING := "abc";\n    fbTest : FB_Test(1, 2, 3);\n    fbTest : FB_Test(A := 1, B := 2, C => 3);\n    fbTest : FB_Test(1, 2, A := 1, B := 2, C => 3);\n    fbTest : FB_Test := (1, 2, 3);\nEND_VAR]
FAILED tests/test_transformer.py::test_global_roundtrip[global_var_declarations-VAR_GLOBAL\nEND_VAR] - RecursionError: maximu...
FAILED tests/test_transformer.py::test_global_roundtrip[global_var_declarations-VAR_GLOBAL CONSTANT\nEND_VAR] - RecursionErro...
FAILED tests/test_transformer.py::test_global_roundtrip[global_var_declarations-VAR_GLOBAL PERSISTENT\nEND_VAR] - RecursionEr...
FAILED tests/test_transformer.py::test_global_roundtrip[global_var_declarations-VAR_GLOBAL CONSTANT PERSISTENT\nEND_VAR] - Re...
FAILED tests/test_transformer.py::test_global_roundtrip[global_var_declarations-VAR_GLOBAL CONSTANT PERSISTENT\n    iValue : INT := 5;\n    fbTest1 : FB_Test(1, 2);\n    fbTest2 : FB_Test(A := 1, B := 2);\n    fbTest3 : FB_TestC;\n    i_iFscEB1Ch0AI AT %I* : INT;\nEND_VAR]
FAILED tests/test_transformer.py::test_fb_roundtrip[function_block_type_declaration-FUNCTION_BLOCK fbName\nEND_FUNCTION_BLOCK]
FAILED tests/test_transformer.py::test_fb_roundtrip[function_block_type_declaration-FUNCTION_BLOCK fbName IMPLEMENTS I_fbName\nEND_FUNCTION_BLOCK]
FAILED tests/test_transformer.py::test_fb_roundtrip[function_block_type_declaration-FUNCTION_BLOCK fbName IMPLEMENTS I_fbName, I_fbName2\nEND_FUNCTION_BLOCK]
FAILED tests/test_transformer.py::test_fb_roundtrip[function_block_type_declaration-FUNCTION_BLOCK ABSTRACT fbName EXTENDS OtherFbName\nEND_FUNCTION_BLOCK]
FAILED tests/test_transformer.py::test_fb_roundtrip[function_block_type_declaration-FUNCTION_BLOCK PRIVATE fbName EXTENDS OtherFbName\nEND_FUNCTION_BLOCK]
FAILED tests/test_transformer.py::test_fb_roundtrip[function_block_type_declaration-FUNCTION_BLOCK PUBLIC fbName EXTENDS OtherFbName\nEND_FUNCTION_BLOCK]
FAILED tests/test_transformer.py::test_fb_roundtrip[function_block_type_declaration-FUNCTION_BLOCK INTERNAL fbName EXTENDS OtherFbName\nEND_FUNCTION_BLOCK]
FAILED tests/test_transformer.py::test_fb_roundtrip[function_block_type_declaration-FUNCTION_BLOCK PROTECTED fbName EXTENDS OtherFbName\nEND_FUNCTION_BLOCK]
FAILED tests/test_transformer.py::test_fb_roundtrip[function_block_type_declaration-FUNCTION_BLOCK FINAL fbName EXTENDS OtherFbName\nEND_FUNCTION_BLOCK]
FAILED tests/test_transformer.py::test_fb_roundtrip[function_block_type_declaration-FUNCTION_BLOCK fbName\nVAR_INPUT\n    bExecute : BOOL;\nEND_VAR\nVAR_OUTPUT\n    iResult : INT;\nEND_VAR\nVAR_IN_OUT\n    iShared : INT;\nEND_VAR\nVAR CONSTANT\n    iConstant : INT := 5;\nEND_VAR\nVAR\n    iInternal : INT;\nEND_VAR\nVAR RETAIN\n    iRetained : INT;\nEND_VAR\nEND_FUNCTION_BLOCK]
FAILED tests/test_transformer.py::test_fb_roundtrip[located_var_declarations-VAR RETAIN\n    iValue AT %IB1 : INT := 5;\nEND_VAR]
FAILED tests/test_transformer.py::test_fb_roundtrip[temp_var_decls-VAR_TEMP\n    iGlobalVar : INT;\nEND_VAR] - RecursionError...
FAILED tests/test_transformer.py::test_fb_roundtrip[function_block_type_declaration-FUNCTION_BLOCK fbName\n    iValue := 1;\n    iValue;\n    iValue S= 1;\n    iValue R= 1;\n    iValue REF= GVL.iTest;\n    fbOther(A := 5, B => iValue, NOT C => iValue1);\n    IF 1 THEN\n        iValue := 1;\n        IF 1 THEN\n            iValue := 1;\n        END_IF\n    END_IF\n    Method();\n    RETURN;\nEND_FUNCTION_BLOCK]
FAILED tests/test_transformer.py::test_fb_roundtrip[function_block_type_declaration-FUNCTION_BLOCK fbName\n    Method();\n    IF 1 THEN\n        EXIT;\n    END_IF\nEND_FUNCTION_BLOCK]
FAILED tests/test_transformer.py::test_fb_roundtrip[function_block_method_declaration-METHOD PRIVATE MethodName : RETURNTYPE\nEND_METHOD]
FAILED tests/test_transformer.py::test_fb_roundtrip[function_block_method_declaration-METHOD PRIVATE MethodName : ARRAY [1..2] OF INT\nEND_METHOD]
FAILED tests/test_transformer.py::test_fb_roundtrip[function_block_method_declaration-METHOD PUBLIC MethodName : RETURNTYPE\nEND_METHOD]
FAILED tests/test_transformer.py::test_fb_roundtrip[function_block_method_declaration-METHOD PUBLIC MethodName\nEND_METHOD]
FAILED tests/test_transformer.py::test_fb_roundtrip[function_block_method_declaration-METHOD MethodName : RETURNTYPE\n    VAR_INPUT\n        bExecute : BOOL;\n    END_VAR\n    VAR_OUTPUT\n        iResult : INT;\n    END_VAR\n    iResult := 5;\nEND_METHOD]
FAILED tests/test_transformer.py::test_fb_roundtrip[function_block_method_declaration-METHOD PUBLIC MethodName\n    VAR_INST\n        bExecute : BOOL;\n    END_VAR\nEND_METHOD]
FAILED tests/test_transformer.py::test_fb_roundtrip[function_block_method_declaration-METHOD PUBLIC ABSTRACT MethodName : LREAL\n    VAR_INPUT\n        I : UINT;\n    END_VAR\nEND_METHOD]
FAILED tests/test_transformer.py::test_fb_roundtrip[function_block_property_declaration-PROPERTY PRIVATE PropertyName : RETURNTYPE\nEND_PROPERTY]
FAILED tests/test_transformer.py::test_fb_roundtrip[function_block_property_declaration-PROPERTY PRIVATE PropertyName : ARRAY [1..2] OF INT\nEND_PROPERTY]
FAILED tests/test_transformer.py::test_fb_roundtrip[function_block_property_declaration-PROPERTY PUBLIC PropertyName : RETURNTYPE\nEND_PROPERTY]
FAILED tests/test_transformer.py::test_fb_roundtrip[function_block_property_declaration-PROPERTY PUBLIC PropertyName\nEND_PROPERTY]
FAILED tests/test_transformer.py::test_fb_roundtrip[function_block_property_declaration-PROPERTY PropertyName : RETURNTYPE\n    VAR_INPUT\n        bExecute : BOOL;\n    END_VAR\n    VAR_OUTPUT\n        iResult : INT;\n    END_VAR\n    iResult := 5;\nEND_PROPERTY]
FAILED tests/test_transformer.py::test_fb_roundtrip[function_block_property_declaration-PROPERTY PUBLIC ABSTRACT PropertyName : LREAL\n    VAR_INPUT\n        I : UINT;\n    END_VAR\nEND_PROPERTY]
FAILED tests/test_transformer.py::test_statement_roundtrip[if_statement-IF 1 THEN\n    iValue := 1;\n    IF 1 THEN\n        iValue := 1;\n    END_IF\nELSIF 2 THEN\n    iValue := 2;\nELSIF 3 THEN\n    iValue := 2;\nELSE\n    iValue := 3;\nEND_IF]
FAILED tests/test_transformer.py::test_statement_roundtrip[if_statement-IF 1 THEN\n    IF 2 THEN\n        IF 3 * x THEN\n            y();\n        ELSE\n        END_IF\n    END_IF\nEND_IF]
FAILED tests/test_transformer.py::test_statement_roundtrip[if_statement-IF 1 AND_THEN 1 THEN\n    y();\nEND_IF] - RecursionEr...
FAILED tests/test_transformer.py::test_statement_roundtrip[if_statement-IF 0 OR_ELSE 1 THEN\n    y();\nEND_IF] - RecursionErr...
FAILED tests/test_transformer.py::test_statement_roundtrip[case_statement-CASE expr OF\n1:\n    abc();\n2, 3, GVL.Constant:\n    def();\nELSE\n    ghi();\nEND_CASE]
FAILED tests/test_transformer.py::test_statement_roundtrip[case_statement-CASE a.b.c^.d OF\n1..10:\n    OneToTen := OneToTen + 1;\nEnumValue:\nEND_CASE]
FAILED tests/test_transformer.py::test_statement_roundtrip[while_statement-WHILE expr\nDO\n    iValue := iValue + 1;\nEND_WHILE]
FAILED tests/test_transformer.py::test_statement_roundtrip[repeat_statement-REPEAT\n    iValue := iValue + 1;\nUNTIL expr\nEND_REPEAT]
FAILED tests/test_transformer.py::test_statement_roundtrip[for_statement-FOR iIndex := 0 TO 10\nDO\n    iValue := iIndex * 2;\nEND_FOR]
FAILED tests/test_transformer.py::test_statement_roundtrip[for_statement-FOR iIndex := 0 TO 10 BY 1\nDO\n    iValue := iIndex * 2;\nEND_FOR]
FAILED tests/test_transformer.py::test_statement_roundtrip[for_statement-FOR iIndex := (iValue - 5) TO iValue * 10 BY iValue MOD 10\nDO\n    arrArray[iIndex] := iIndex * 2;\nEND_FOR]
FAILED tests/test_transformer.py::test_statement_roundtrip[for_statement-FOR iIndex[1] := 0 TO 10\nDO\n    iValue := iIndex * 2;\nEND_FOR]
FAILED tests/test_transformer.py::test_function_roundtrip[int_with_input] - RecursionError: maximum recursion depth exceeded ...
FAILED tests/test_transformer.py::test_function_roundtrip[int_with_pointer_retval] - RecursionError: maximum recursion depth ...
FAILED tests/test_transformer.py::test_function_roundtrip[int_with_input_output] - RecursionError: maximum recursion depth ex...
FAILED tests/test_transformer.py::test_function_roundtrip[no_return_type] - RecursionError: maximum recursion depth exceeded ...
FAILED tests/test_transformer.py::test_function_roundtrip[dotted_return_type] - RecursionError: maximum recursion depth excee...
FAILED tests/test_transformer.py::test_program_roundtrip[program_declaration-PROGRAM ProgramName\nEND_PROGRAM] - RecursionErr...
FAILED tests/test_transformer.py::test_program_roundtrip[program_declaration-PROGRAM ProgramName\n    VAR_INPUT\n        iValue : INT;\n    END_VAR\n    VAR_ACCESS\n        AccessName : SymbolicVariable : TypeName READ_WRITE;\n    END_VAR\n    iValue := iValue + 1;\nEND_PROGRAM]
FAILED tests/test_transformer.py::test_input_output_comments[input_output_declarations-/ Var in and out\n(* Var in and out *)\nVAR_IN_OUT\n    / Variable\n    iVar : INT;\nEND_VAR]
FAILED tests/test_transformer.py::test_incomplete_located_var_decls[incomplete_located_var_declarations-VAR\n    iValue AT %Q* : INT;\n    sValue AT %I* : STRING [255];\n    wsValue AT %I* : WSTRING [255];\nEND_VAR]
FAILED tests/test_transformer.py::test_incomplete_located_var_decls[incomplete_located_var_declarations-VAR RETAIN\n    iValue AT %I* : INT;\n    iValue1 AT %Q* : INT;\nEND_VAR]
FAILED tests/test_transformer.py::test_data_type_declaration[data_type_declaration-TYPE\nEND_TYPE] - RecursionError: maximum ...
FAILED tests/test_transformer.py::test_data_type_declaration[data_type_declaration-TYPE TypeName :\n    STRUCT\n        xPLC_CnBitsValid : BOOL;\n        xPLC_CnBits : ARRAY [0..20] OF BYTE;\n    END_STRUCT\nEND_TYPE]
FAILED tests/test_transformer.py::test_data_type_declaration[data_type_declaration-TYPE ArrayTypeName : ARRAY [1..10, 2..20] OF INT;\nEND_TYPE]
FAILED tests/test_transformer.py::test_data_type_declaration[data_type_declaration-TYPE StringTypeName : STRING[10] := 'Literal';\nEND_TYPE]
FAILED tests/test_transformer.py::test_data_type_declaration[data_type_declaration-TYPE SimpleTypeName EXTENDS OtherType : POINTER TO INT;\nEND_TYPE]
FAILED tests/test_transformer.py::test_data_type_declaration[data_type_declaration-TYPE SubrangeTypeName : POINTER TO INT (1..5);\nEND_TYPE]
FAILED tests/test_transformer.py::test_data_type_declaration[data_type_declaration-TYPE EnumeratedTypeName : REFERENCE TO Identifier;\nEND_TYPE]
FAILED tests/test_transformer.py::test_data_type_declaration[data_type_declaration-TYPE EnumeratedTypeName : REFERENCE TO (IdentifierA, INT#IdentifierB := 1);\nEND_TYPE]
FAILED tests/test_transformer.py::test_data_type_declaration[data_type_declaration-TYPE TypeName :\n    UNION\n        intval : INT;\n        as_bytes : ARRAY [0..2] OF BYTE;\n    END_UNION\nEND_TYPE]
FAILED tests/test_transformer.py::test_data_type_declaration[data_type_declaration-TYPE TypeName :\n    UNION\n        intval : INT;\n        enum : (iValue := 1, iValue2 := 2) INT;\n    END_UNION\nEND_TYPE]

Random thoughts

• It's likely that the issue is due to mistaken/incorrect type hints. There is at least a tiny possibility that this is an apischema bug.
• Type hints for the problematic ones in the failed tests above need reviewing to see what's wrong.
• CI should be updated to "run test suite with optional dependencies" and "run test suite without optional dependencies" at some point
• Ideally, the round-tripping of code -> dataclass -> code and code -> dataclass -> JSON -> dataclass would be separate in the test suite. As of now, these are only just tacked on in roundtrip_rule.