Function TestTranslatePositionErrorPropagationColumn

pkg/lsp/translator_test.go:416–503

TestTranslatePositionErrorPropagationColumn tests column mapping for error propagation transforms. This is a REGRESSION TEST for the issue where hovering on `extractUserID` in Dingo shows hover info for `tmp` instead, because column positions differ: - Dingo: `userID := extractUserID(r)?` → extract

(t *testing.T)

//
// The test verifies that column positions are correctly mapped for transformed lines.
func TestTranslatePositionErrorPropagationColumn(t *testing.T) {
	// Realistic error propagation example
	// Dingo line: "	userID := extractUserID(r)?\n"
	// Go line:    "	tmp, err := extractUserID(r)\n"
	//
	// Character positions (1-indexed):
	//   Dingo: extractUserID starts at col 12 (after tab + "userID := ")
	//   Go:    extractUserID starts at col 14 (after tab + "tmp, err := ")
	dingoSrc := "\tuserID := extractUserID(r)?\n"
	goSrc := "\ttmp, err := extractUserID(r)\n"

	// Error propagation expands 1 dingo line to 5 go lines typically,
	// but for this test we simplify to just the first line mapping
	mappings := []sourcemap.LineMapping{
		{DingoLine: 1, GoLineStart: 1, GoLineEnd: 1, Kind: "error_prop"},
	}

	// Column mapping for the function call expression
	// Dingo: "\tuserID := extractUserID(r)?" - extractUserID at col 12 (1-indexed)
	// Go:    "\ttmp, err := extractUserID(r)" - extractUserID at col 14 (1-indexed)
	// Offset = 14 - 12 = +2 (Go has 2 more leading chars due to "tmp, err" vs "userID")
	columnMappings := []sourcemap.ColumnMapping{
		{
			DingoLine: 1,
			DingoCol:  12, // 1-indexed position of 'e' in extractUserID
			GoLine:    1,
			GoCol:     14, // 1-indexed position of 'e' in extractUserID
			Length:    13, // length of "extractUserID"
			Kind:      "error_prop",
		},
	}

	reader := createMockReaderWithColumns(t, dingoSrc, goSrc, mappings, columnMappings)
	defer reader.Close()

	goPath := "/test/file.go"
	dingoPath := "/test/file.dingo"

	cache := &mockSourceMapGetter{
		readers: map[string]*dmap.Reader{
			goPath: reader,
		},
	}

	translator := NewTranslator(cache)
	dingoURI := lspuri.File(dingoPath)

	// Test: Position on 'extractUserID' in Dingo (col 12, 0-indexed = 11)
	// In Dingo: "\tuserID := extractUserID(r)?"
	//            ^          ^
	//            0          11 (0-indexed)
	dingoPos := protocol.Position{Line: 0, Character: 11}

	newURI, newPos, err := translator.TranslatePosition(dingoURI, dingoPos, DingoToGo)
	if err != nil {
		t.Fatalf("TranslatePosition failed: %v", err)
	}