Implemented functions FCreate() and FOpen()

[Irwin1985]

• Mapped VFP nAttribute file modes to X# native FO_* and FC_* constants.
• Implemented buffering translation for FOPEN (modes 10, 11, 12 mapped to FO_UNBUFFERED).
• Updated FoxProFunctions attributes from Stub to Full.
• Added related Unit Test to verify exact VFP return values (-1 on error) and proper file handle creation.

[Copilot]

Pull request overview

Implements the Visual FoxPro-compatible FCREATE() and FOPEN() runtime wrappers in XSharp.VFP by delegating to XSharp.Core file APIs and adds unit tests to validate expected handle/error behavior.

Changes:

• Implemented FCreate() to call XSharp.Core.Functions.FCreate() and return the handle as INT64.
• Implemented FOpen() with VFP nAttribute → FO_* mode translation (including unbuffered modes) and SET PATH resolution via File()/FPathName().
• Added unit tests covering create/open success paths, missing-file error return, and SET PATH lookup.

Reviewed changes

Copilot reviewed 2 out of 2 changed files in this pull request and generated 3 comments.

File	Description
src/Runtime/XSharp.VFP/RuntimeCoreWrappers.prg	Adds concrete implementations for FCreate() and FOpen() and marks both functions as Full.
src/Runtime/XSharp.VFP.Tests/MiscTests.prg	Adds file I/O unit tests for FCreate()/FOpen() and SET PATH behavior.

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[Copilot]

In the SWITCH on nAttribute, CASE 0 does not assign nMode, so the behavior relies on nMode’s implicit default value. This makes the default open mode ambiguous and easy to break if initialization rules change. Assign the intended default mode explicitly for CASE 0 (or initialize nMode when declared) so FOpen(cFileName, 0) is self-documenting and consistent with the other cases.

Suggested change

	CASE 0
	CASE 0; nMode := FO_READ | FO_SHARED

[Copilot]

This test’s expected-failure case uses a hardcoded relative filename ("non_existent_file.txt"). If that file happens to exist in the current working directory (or is found via a prior SET PATH), the test will become flaky and fail unexpectedly. Use a unique temp path (e.g., GUID-based under Path.GetTempPath()) and assert it does not exist before calling FOpen.

Suggested change

	LOCAL nBadHandle AS INT64
	nBadHandle := FOpen("non_existent_file.txt", 0)
	LOCAL cBadFile AS STRING
	LOCAL nBadHandle AS INT64
	cBadFile := Path.Combine(Path.GetTempPath(), "vfp_test_" + Guid.NewGuid():ToString("N") + ".txt")
	Assert.False(FILE(cBadFile))
	nBadHandle := FOpen(cBadFile, 0)

[Copilot]

FCreateAndFOpenTest() deletes the temp file only at the end of the method. If an assertion fails earlier, the temp file and/or an open handle may be left behind, which can pollute subsequent runs. Wrap the test body in TRY/FINALLY and ensure FClose() (when needed) and deletion of cFile happen in FINALLY.

Suggested change

	cFile := Path.Combine(Path.GetTempPath(), "vfp_test_" + Guid.NewGuid():ToString("N") + ".txt")
	&& 1. Test FCREATE()
	nHandle := FCreate(cFile, 0)
	Assert.True(nHandle > 0, "FCreate should return a valid handle")
	nWritten := FPuts(nHandle, "XSharp VFP File Test")
	Assert.True(nWritten > 0, "Should have written data in the file")
	FClose(nHandle)
	&& 2. Test FOPEN()
	nHandle := FOpen(cFile, 0)
	Assert.True(nHandle > 0, "FOpen should open existing file")
	FClose(nHandle)
	&& 3. Test expected failure (non existent file)
	LOCAL nBadHandle AS INT64
	nBadHandle := FOpen("non_existent_file.txt", 0)
	Assert.Equal(-1L, nBadHandle)
	IF FILE(cFile)
	File.Delete(cFile)
	ENDIF
	LOCAL nBadHandle AS INT64
	cFile := Path.Combine(Path.GetTempPath(), "vfp_test_" + Guid.NewGuid():ToString("N") + ".txt")
	nHandle := 0
	TRY
	&& 1. Test FCREATE()
	nHandle := FCreate(cFile, 0)
	Assert.True(nHandle > 0, "FCreate should return a valid handle")
	nWritten := FPuts(nHandle, "XSharp VFP File Test")
	Assert.True(nWritten > 0, "Should have written data in the file")
	IF nHandle > 0
	FClose(nHandle)
	nHandle := 0
	ENDIF
	&& 2. Test FOPEN()
	nHandle := FOpen(cFile, 0)
	Assert.True(nHandle > 0, "FOpen should open existing file")
	IF nHandle > 0
	FClose(nHandle)
	nHandle := 0
	ENDIF
	&& 3. Test expected failure (non existent file)
	nBadHandle := FOpen("non_existent_file.txt", 0)
	Assert.Equal(-1L, nBadHandle)
	FINALLY
	IF nHandle > 0
	FClose(nHandle)
	ENDIF
	IF FILE(cFile)
	File.Delete(cFile)
	ENDIF
	END TRY