Implemented more robust LSP diagnostics and better parsing logic

cmd/mdt/main.go

@@ -138,6 +138,7 @@ func runCheck(args []string) {
 	}
 
 	tree := index.NewProjectTree()
+	syntaxErrors := 0
 
 	for _, file := range args {
 		content, err := os.ReadFile(file)
@@ -147,14 +148,18 @@ func runCheck(args []string) {
 		}
 
 		p := parser.NewParser(string(content))
-		config, err := p.Parse()
+		config, _ := p.Parse()
-		if err != nil {
+		if len(p.Errors()) > 0 {
-			logger.Printf("%s: Grammar error: %v\n", file, err)
+			syntaxErrors += len(p.Errors())
-			continue
+			for _, e := range p.Errors() {
+				logger.Printf("%s: Grammar error: %v\n", file, e)
+			}
 		}
 
+		if config != nil {
 			tree.AddFile(file, config)
 		}
+	}
 
 	v := validator.NewValidator(tree, ".")
 	v.ValidateProject()
@@ -167,8 +172,9 @@ func runCheck(args []string) {
 		logger.Printf("%s:%d:%d: %s: %s\n", diag.File, diag.Position.Line, diag.Position.Column, level, diag.Message)
 	}
 
-	if len(v.Diagnostics) > 0 {
+	totalIssues := len(v.Diagnostics) + syntaxErrors
-		logger.Printf("\nFound %d issues.\n", len(v.Diagnostics))
+	if totalIssues > 0 {
+		logger.Printf("\nFound %d issues.\n", totalIssues)
 	} else {
 		logger.Println("No issues found.")
 	}

docs/CODE_DOCUMENTATION.md

@@ -43,7 +43,7 @@ The brain of the system. It maintains a holistic view of the project.
 *   **ProjectTree**: The central data structure. It holds the root of the configuration hierarchy (`Root`), references, and isolated files.
 *   **ProjectNode**: Represents a logical node in the configuration. Since a node can be defined across multiple files (fragments), `ProjectNode` aggregates these fragments. It also stores locally defined variables in its `Variables` map.
 *   **NodeMap**: A hash map index (`map[string][]*ProjectNode`) for $O(1)$ symbol lookups, optimizing `FindNode` operations.
-*   **Reference Resolution**: The `ResolveReferences` method links `Reference` objects to their target `ProjectNode` or `VariableDefinition`. It uses `resolveScopedName` to respect lexical scoping rules, searching up the hierarchy from the reference's container.
+*   **Reference Resolution**: The `ResolveReferences` method links `Reference` objects to their target `ProjectNode` or `VariableDefinition`. It uses `ResolveName` (exported) which respects lexical scoping rules by searching the hierarchy upwards from the reference's container, using `FindNode` for deep searches within each scope.
 
 ### 3. `internal/validator`
 
@@ -100,12 +100,13 @@ Manages CUE schemas.
 5.  Diagnostics are printed (CLI) or published via `textDocument/publishDiagnostics` (LSP).
 
 ### Threading Check Logic
-1.  Finds the `RealTimeApplication` node.
+1.  Iterates all `RealTimeApplication` nodes found in the project.
-2.  Iterates through `States` and `Threads`.
+2.  For each App:
-3.  For each Thread, resolves the `Functions` (GAMs).
+    1.  Finds `States` and `Threads`.
-4.  For each GAM, resolves connected `DataSources` via Input/Output signals.
+    2.  For each Thread, resolves the `Functions` (GAMs).
-5.  Maps `DataSource -> Thread` within the context of a State.
+    3.  For each GAM, resolves connected `DataSources` via Input/Output signals.
-6.  If a DataSource is seen in >1 Thread, it checks the `#meta.multithreaded` property. If false (default), an error is raised.
+    4.  Maps `DataSource -> Thread` within the context of a State.
+    5.  If a DataSource is seen in >1 Thread, it checks the `#meta.multithreaded` property. If false (default), an error is raised.
 
 ### INOUT Ordering Logic
 1.  Iterates Threads.

docs/CONFIGURATION_GUIDE.md

@@ -173,9 +173,11 @@ You can define variables using `#var`. The type expression supports CUE syntax.
 ```
 
 ### Usage
-Reference a variable using `@`:
+Reference a variable using `$` (preferred) or `@`:
 
 ```marte
+Field = $MyVar
+// or
 Field = @MyVar
 ```
 
@@ -187,7 +189,7 @@ You can use operators in field values. Supported operators:
 ```marte
 Field1 = 10 + 20 * 2  // 50
 Field2 = "Hello " .. "World"
-Field3 = @MyVar + 5
+Field3 = $MyVar + 5
 ```
 
 ### Build Override
@@ -197,3 +199,21 @@ You can override variable values during build:
 mdt build -vMyVar=200 -vEnv="PROD" src/*.marte
 ```
 
+## 7. Validation Rules (Detail)
+
+### Data Flow Validation
+`mdt` checks for logical data flow errors:
+- **Consumed before Produced**: If a GAM reads an INOUT signal that hasn't been written by a previous GAM in the same cycle, an error is reported.
+- **Produced but not Consumed**: If a GAM writes an INOUT signal that is never read by subsequent GAMs, a warning is reported.
+- **Initialization**: Providing a `Value` field in an `InputSignal` treats it as "produced" (initialized), resolving "Consumed before Produced" errors.
+
+### Threading Rules
+A DataSource that is **not** marked as multithreaded (default) cannot be used by GAMs running in different threads within the same State.
+
+To allow sharing, the DataSource class in the schema must have `#meta: multithreaded: true`.
+
+### Implicit vs Explicit Signals
+- **Explicit**: Signal defined in `DataSource.Signals`.
+- **Implicit**: Signal used in GAM but not defined in DataSource. `mdt` reports a warning unless suppressed.
+
+

docs/EDITOR_INTEGRATION.md

@@ -2,11 +2,12 @@
 
 `mdt` includes a Language Server Protocol (LSP) implementation that provides features like:
 
-- Syntax highlighting and error reporting
+- Syntax highlighting and error reporting (Parser & Semantic)
 - Auto-completion
 - Go to Definition / References
 - Hover documentation
 - Symbol renaming
+- Incremental synchronization (Robust)
 
 The LSP server is started via the command:
 

internal/index/index.go

@@ -435,7 +435,7 @@ func (pt *ProjectTree) ResolveReferences() {
 			continue
 		}
 
-		ref.Target = pt.resolveScopedName(container, ref.Name)
+		ref.Target = pt.ResolveName(container, ref.Name, nil)
 	}
 }
 
@@ -617,51 +617,19 @@ func (pt *ProjectTree) findNodeContaining(node *ProjectNode, file string, pos pa
 	return nil
 }
 
-func (pt *ProjectTree) resolveScopedName(ctx *ProjectNode, name string) *ProjectNode {
+func (pt *ProjectTree) ResolveName(ctx *ProjectNode, name string, predicate func(*ProjectNode) bool) *ProjectNode {
 	if ctx == nil {
-		return pt.FindNode(pt.Root, name, nil)
+		return pt.FindNode(pt.Root, name, predicate)
 	}
 
-	parts := strings.Split(name, ".")
-	first := parts[0]
-	normFirst := NormalizeName(first)
-
-	var startNode *ProjectNode
 	curr := ctx
-
 	for curr != nil {
-		if child, ok := curr.Children[normFirst]; ok {
+		if found := pt.FindNode(curr, name, predicate); found != nil {
-			startNode = child
+			return found
-			break
 		}
 		curr = curr.Parent
 	}
-
-	if startNode == nil && ctx != pt.Root {
-		if child, ok := pt.Root.Children[normFirst]; ok {
-			startNode = child
-		}
-	}
-
-	if startNode == nil {
-		// Fallback to deep search from context root
-		root := ctx
-		for root.Parent != nil {
-			root = root.Parent
-		}
-		return pt.FindNode(root, name, nil)
-	}
-
-	curr = startNode
-	for i := 1; i < len(parts); i++ {
-		norm := NormalizeName(parts[i])
-		if child, ok := curr.Children[norm]; ok {
-			curr = child
-		} else {
 	return nil
-		}
-	}
-	return curr
 }
 
 func (pt *ProjectTree) ResolveVariable(ctx *ProjectNode, name string) *VariableInfo {

internal/lsp/server.go

@@ -336,13 +336,9 @@ func HandleDidOpen(params DidOpenTextDocumentParams) {
 	path := uriToPath(params.TextDocument.URI)
 	Documents[params.TextDocument.URI] = params.TextDocument.Text
 	p := parser.NewParser(params.TextDocument.Text)
-	config, err := p.Parse()
+	config, _ := p.Parse()
 
-	if err != nil {
+	publishParserErrors(params.TextDocument.URI, p.Errors())
-		publishParserError(params.TextDocument.URI, err)
-	} else {
-		publishParserError(params.TextDocument.URI, nil)
-	}
 
 	if config != nil {
 		Tree.AddFile(path, config)
@@ -369,13 +365,9 @@ func HandleDidChange(params DidChangeTextDocumentParams) {
 	Documents[uri] = text
 	path := uriToPath(uri)
 	p := parser.NewParser(text)
-	config, err := p.Parse()
+	config, _ := p.Parse()
 
-	if err != nil {
+	publishParserErrors(uri, p.Errors())
-		publishParserError(uri, err)
-	} else {
-		publishParserError(uri, nil)
-	}
 
 	if config != nil {
 		Tree.AddFile(path, config)
@@ -465,6 +457,9 @@ func runValidation(_ string) {
 	// Collect all known files to ensure we clear diagnostics for fixed files
 	knownFiles := make(map[string]bool)
 	collectFiles(Tree.Root, knownFiles)
+	for _, node := range Tree.IsolatedFiles {
+		collectFiles(node, knownFiles)
+	}
 
 	// Initialize all known files with empty diagnostics
 	for f := range knownFiles {
@@ -473,8 +468,10 @@ func runValidation(_ string) {
 
 	for _, d := range v.Diagnostics {
 		severity := 1 // Error
+		levelStr := "ERROR"
 		if d.Level == validator.LevelWarning {
 			severity = 2 // Warning
+			levelStr = "WARNING"
 		}
 
 		diag := LSPDiagnostic{
@@ -483,7 +480,7 @@ func runValidation(_ string) {
 				End:   Position{Line: d.Position.Line - 1, Character: d.Position.Column - 1 + 10}, // Arbitrary length
 			},
 			Severity: severity,
-			Message:  d.Message,
+			Message:  fmt.Sprintf("%s: %s", levelStr, d.Message),
 			Source:   "mdt",
 		}
 
@@ -508,20 +505,10 @@ func runValidation(_ string) {
 	}
 }
 
-func publishParserError(uri string, err error) {
+func publishParserErrors(uri string, errors []error) {
-	if err == nil {
+	diagnostics := []LSPDiagnostic{}
-		notification := JsonRpcMessage{
-			Jsonrpc: "2.0",
-			Method:  "textDocument/publishDiagnostics",
-			Params: mustMarshal(PublishDiagnosticsParams{
-				URI:         uri,
-				Diagnostics: []LSPDiagnostic{},
-			}),
-		}
-		send(notification)
-		return
-	}
 
+	for _, err := range errors {
 		var line, col int
 		var msg string
 		// Try parsing "line:col: message"
@@ -547,19 +534,24 @@ func publishParserError(uri string, err error) {
 			Message:  msg,
 			Source:   "mdt-parser",
 		}
+		diagnostics = append(diagnostics, diag)
+	}
 
 	notification := JsonRpcMessage{
 		Jsonrpc: "2.0",
 		Method:  "textDocument/publishDiagnostics",
 		Params: mustMarshal(PublishDiagnosticsParams{
 			URI:         uri,
-			Diagnostics: []LSPDiagnostic{diag},
+			Diagnostics: diagnostics,
 		}),
 	}
 	send(notification)
 }
 
 func collectFiles(node *index.ProjectNode, files map[string]bool) {
+	if node == nil {
+		return
+	}
 	for _, frag := range node.Fragments {
 		files[frag.File] = true
 	}

internal/parser/parser.go

@@ -299,6 +299,8 @@ func (p *Parser) parseAtom() (Value, bool) {
 		return &ReferenceValue{Position: tok.Position, Value: tok.Value}, true
 	case TokenVariableReference:
 		return &VariableReferenceValue{Position: tok.Position, Name: tok.Value}, true
+	case TokenObjectIdentifier:
+		return &VariableReferenceValue{Position: tok.Position, Name: tok.Value}, true
 	case TokenLBrace:
 		arr := &ArrayValue{Position: tok.Position}
 		for {
@@ -380,3 +382,7 @@ func (p *Parser) parseVariableDefinition(startTok Token) (Definition, bool) {
 		DefaultValue: defVal,
 	}, true
 }
+
+func (p *Parser) Errors() []error {
+	return p.errors
+}

internal/validator/validator.go

@@ -304,7 +304,7 @@ func (v *Validator) validateGAMSignal(gamNode, signalNode *index.ProjectNode, di
 		return // Ignore implicit signals or missing datasource (handled elsewhere if mandatory)
 	}
 
-	dsNode := v.resolveReference(dsName, v.getNodeFile(signalNode), isDataSource)
+	dsNode := v.resolveReference(dsName, signalNode, isDataSource)
 	if dsNode == nil {
 		v.Diagnostics = append(v.Diagnostics, Diagnostic{
 			Level:    LevelError,
@@ -565,17 +565,8 @@ func (v *Validator) getFieldValue(f *parser.Field, ctx *index.ProjectNode) strin
 	return ""
 }
 
-func (v *Validator) resolveReference(name string, file string, predicate func(*index.ProjectNode) bool) *index.ProjectNode {
+func (v *Validator) resolveReference(name string, ctx *index.ProjectNode, predicate func(*index.ProjectNode) bool) *index.ProjectNode {
-	if isoNode, ok := v.Tree.IsolatedFiles[file]; ok {
+	return v.Tree.ResolveName(ctx, name, predicate)
-		if found := v.Tree.FindNode(isoNode, name, predicate); found != nil {
-			return found
-		}
-		return nil
-	}
-	if v.Tree.Root == nil {
-		return nil
-	}
-	return v.Tree.FindNode(v.Tree.Root, name, predicate)
 }
 
 func (v *Validator) getNodeClass(node *index.ProjectNode) string {
@@ -740,7 +731,7 @@ func (v *Validator) checkFunctionsArray(node *index.ProjectNode, fields map[stri
 		if arr, ok := f.Value.(*parser.ArrayValue); ok {
 			for _, elem := range arr.Elements {
 				if ref, ok := elem.(*parser.ReferenceValue); ok {
-					target := v.resolveReference(ref.Value, v.getNodeFile(node), isGAM)
+					target := v.resolveReference(ref.Value, node, isGAM)
 					if target == nil {
 						v.Diagnostics = append(v.Diagnostics, Diagnostic{
 							Level:    LevelError,
@@ -799,19 +790,20 @@ func (v *Validator) CheckDataSourceThreading() {
 		return
 	}
 
-	// 1. Find RealTimeApplication
+	var appNodes []*index.ProjectNode
-	var appNode *index.ProjectNode
 	findApp := func(n *index.ProjectNode) {
 		if cls, ok := n.Metadata["Class"]; ok && cls == "RealTimeApplication" {
-			appNode = n
+			appNodes = append(appNodes, n)
 		}
 	}
 	v.Tree.Walk(findApp)
 
-	if appNode == nil {
+	for _, appNode := range appNodes {
-		return
+		v.checkAppDataSourceThreading(appNode)
 	}
+}
 
+func (v *Validator) checkAppDataSourceThreading(appNode *index.ProjectNode) {
 	// 2. Find States
 	var statesNode *index.ProjectNode
 	if s, ok := appNode.Children["States"]; ok {
@@ -882,7 +874,7 @@ func (v *Validator) getThreadGAMs(thread *index.ProjectNode) []*index.ProjectNod
 		if arr, ok := f.Value.(*parser.ArrayValue); ok {
 			for _, elem := range arr.Elements {
 				if ref, ok := elem.(*parser.ReferenceValue); ok {
-					target := v.resolveReference(ref.Value, v.getNodeFile(thread), isGAM)
+					target := v.resolveReference(ref.Value, thread, isGAM)
 					if target != nil {
 						gams = append(gams, target)
 					}
@@ -904,7 +896,7 @@ func (v *Validator) getGAMDataSources(gam *index.ProjectNode) []*index.ProjectNo
 			fields := v.getFields(sig)
 			if dsFields, ok := fields["DataSource"]; ok && len(dsFields) > 0 {
 				dsName := v.getFieldValue(dsFields[0], sig)
-				dsNode := v.resolveReference(dsName, v.getNodeFile(sig), isDataSource)
+				dsNode := v.resolveReference(dsName, sig, isDataSource)
 				if dsNode != nil {
 					dsMap[dsNode] = true
 				}
@@ -938,18 +930,20 @@ func (v *Validator) CheckINOUTOrdering() {
 		return
 	}
 
-	var appNode *index.ProjectNode
+	var appNodes []*index.ProjectNode
 	findApp := func(n *index.ProjectNode) {
 		if cls, ok := n.Metadata["Class"]; ok && cls == "RealTimeApplication" {
-			appNode = n
+			appNodes = append(appNodes, n)
 		}
 	}
 	v.Tree.Walk(findApp)
 
-	if appNode == nil {
+	for _, appNode := range appNodes {
-		return
+		v.checkAppINOUTOrdering(appNode)
 	}
+}
 
+func (v *Validator) checkAppINOUTOrdering(appNode *index.ProjectNode) {
 	var statesNode *index.ProjectNode
 	if s, ok := appNode.Children["States"]; ok {
 		statesNode = s
@@ -1049,7 +1043,7 @@ func (v *Validator) processGAMSignalsForOrdering(gam *index.ProjectNode, contain
 		if dsNode == nil {
 			if dsFields, ok := fields["DataSource"]; ok && len(dsFields) > 0 {
 				dsName := v.getFieldValue(dsFields[0], sig)
-				dsNode = v.resolveReference(dsName, v.getNodeFile(sig), isDataSource)
+				dsNode = v.resolveReference(dsName, sig, isDataSource)
 			}
 			if aliasFields, ok := fields["Alias"]; ok && len(aliasFields) > 0 {
 				sigName = v.getFieldValue(aliasFields[0], sig)

test/lsp_fuzz_test.go

@@ -0,0 +1,101 @@
+package integration
+
+import (
+	"math/rand"
+	"testing"
+	"time"
+
+	"github.com/marte-community/marte-dev-tools/internal/lsp"
+)
+
+func TestIncrementalFuzz(t *testing.T) {
+	// Initialize
+	lsp.Documents = make(map[string]string)
+	uri := "file://fuzz.marte"
+	currentText := ""
+	lsp.Documents[uri] = currentText
+
+	rand.Seed(time.Now().UnixNano())
+
+	// Apply 1000 random edits
+	for i := 0; i < 1000; i++ {
+		// Randomly choose Insert or Delete
+		isInsert := rand.Intn(2) == 0
+		
+		change := lsp.TextDocumentContentChangeEvent{}
+		
+		// Use simple ascii string
+		length := len(currentText)
+        
+		if isInsert || length == 0 {
+			// Insert
+			pos := 0
+			if length > 0 {
+				pos = rand.Intn(length + 1)
+			}
+		
+			insertStr := "X"
+			if rand.Intn(5) == 0 { insertStr = "\n" }
+			if rand.Intn(10) == 0 { insertStr = "longstring" }
+		
+            // Calculate Line/Char for pos
+            line, char := offsetToLineChar(currentText, pos)
+            
+			change.Range = &lsp.Range{
+				Start: lsp.Position{Line: line, Character: char},
+				End:   lsp.Position{Line: line, Character: char},
+			}
+			change.Text = insertStr
+			
+			// Expected
+			currentText = currentText[:pos] + insertStr + currentText[pos:]
+		} else {
+			// Delete
+			start := rand.Intn(length)
+			end := start + 1 + rand.Intn(length - start) // at least 1 char
+			
+			// Range
+            l1, c1 := offsetToLineChar(currentText, start)
+            l2, c2 := offsetToLineChar(currentText, end)
+            
+			change.Range = &lsp.Range{
+				Start: lsp.Position{Line: l1, Character: c1},
+				End:   lsp.Position{Line: l2, Character: c2},
+			}
+			change.Text = ""
+			
+			currentText = currentText[:start] + currentText[end:]
+		}
+		
+		// Apply
+		lsp.HandleDidChange(lsp.DidChangeTextDocumentParams{
+			TextDocument:   lsp.VersionedTextDocumentIdentifier{URI: uri, Version: i},
+			ContentChanges: []lsp.TextDocumentContentChangeEvent{change},
+		})
+		
+		// Verify
+		if lsp.Documents[uri] != currentText {
+			t.Fatalf("Fuzz iteration %d failed.\nExpected len: %d\nGot len:      %d\nChange: %+v", i, len(currentText), len(lsp.Documents[uri]), change)
+		}
+	}
+}
+
+func offsetToLineChar(text string, offset int) (int, int) {
+    line := 0
+    char := 0
+    for i, r := range text {
+        if i == offset {
+            return line, char
+        }
+        if r == '\n' {
+            line++
+            char = 0
+        } else {
+            char++
+        }
+    }
+    if offset == len(text) {
+        return line, char
+    }
+    return -1, -1
+}

test/lsp_incremental_correctness_test.go

@@ -0,0 +1,204 @@
+package integration
+
+import (
+	"bytes"
+	"strings"
+	"testing"
+
+	"github.com/marte-community/marte-dev-tools/internal/index"
+	"github.com/marte-community/marte-dev-tools/internal/lsp"
+	"github.com/marte-community/marte-dev-tools/internal/schema"
+)
+
+func TestIncrementalCorrectness(t *testing.T) {
+	lsp.Documents = make(map[string]string)
+	uri := "file://test.txt"
+	initial := "12345\n67890"
+	lsp.Documents[uri] = initial
+
+	// Edit 1: Insert "A" at 0:1 -> "1A2345\n67890"
+	change1 := lsp.TextDocumentContentChangeEvent{
+		Range: &lsp.Range{Start: lsp.Position{Line: 0, Character: 1}, End: lsp.Position{Line: 0, Character: 1}},
+		Text:  "A",
+	}
+	lsp.HandleDidChange(lsp.DidChangeTextDocumentParams{
+		TextDocument:   lsp.VersionedTextDocumentIdentifier{URI: uri},
+		ContentChanges: []lsp.TextDocumentContentChangeEvent{change1},
+	})
+
+	if lsp.Documents[uri] != "1A2345\n67890" {
+		t.Errorf("Edit 1 failed: %q", lsp.Documents[uri])
+	}
+
+	// Edit 2: Delete newline (merge lines)
+	// "1A2345\n67890" -> "1A234567890"
+	// \n is at index 6. 
+	// 0:6 points to \n? "1A2345" length is 6.
+	// So 0:6 is AFTER '5', at '\n'.
+	// 1:0 is AFTER '\n', at '6'.
+	// Range 0:6 - 1:0 covers '\n'.
+	change2 := lsp.TextDocumentContentChangeEvent{
+		Range: &lsp.Range{Start: lsp.Position{Line: 0, Character: 6}, End: lsp.Position{Line: 1, Character: 0}},
+		Text:  "",
+	}
+	lsp.HandleDidChange(lsp.DidChangeTextDocumentParams{
+		TextDocument:   lsp.VersionedTextDocumentIdentifier{URI: uri},
+		ContentChanges: []lsp.TextDocumentContentChangeEvent{change2},
+	})
+
+	if lsp.Documents[uri] != "1A234567890" {
+		t.Errorf("Edit 2 failed: %q", lsp.Documents[uri])
+	}
+
+	// Edit 3: Add newline at end
+	// "1A234567890" len 11.
+	// 0:11.
+	change3 := lsp.TextDocumentContentChangeEvent{
+		Range: &lsp.Range{Start: lsp.Position{Line: 0, Character: 11}, End: lsp.Position{Line: 0, Character: 11}},
+		Text:  "\n",
+	}
+	lsp.HandleDidChange(lsp.DidChangeTextDocumentParams{
+		TextDocument:   lsp.VersionedTextDocumentIdentifier{URI: uri},
+		ContentChanges: []lsp.TextDocumentContentChangeEvent{change3},
+	})
+
+	if lsp.Documents[uri] != "1A234567890\n" {
+		t.Errorf("Edit 3 failed: %q", lsp.Documents[uri])
+	}
+}
+
+func TestIncrementalAppValidation(t *testing.T) {
+	// Setup
+	lsp.Tree = index.NewProjectTree()
+	lsp.Documents = make(map[string]string)
+	lsp.GlobalSchema = schema.LoadFullSchema(".")
+	var buf bytes.Buffer
+	lsp.Output = &buf
+
+	content := `// Test app
++App = {
+  Class = RealTimeApplication
+  +Data = {
+    Class = ReferenceContainer
+    DefaultDataSource = DDB
+    +DDB = {
+      Class = GAMDataSource
+    }
+    +TimingDataSource = {
+      Class = TimingDataSource
+    }
+  }
+  +Functions = {
+    Class = ReferenceContainer
+    +A = {
+      Class = IOGAM
+      InputSignals = {
+        A = {
+          DataSource = DDB
+          Type = uint32
+          // Placeholder
+        }
+      }
+      OutputSignals = {
+        B = {
+          DataSource = DDB
+          Type = uint32
+        }
+      }
+    }
+  }
+  +States = {
+    Class = ReferenceContainer
+    +State = {
+      Class =RealTimeState
+      Threads = {
+        +Th1 = {
+          Class = RealTimeThread
+          Functions = {A}
+        }
+      }
+    }
+  }
+  +Scheduler = {
+    Class = GAMScheduler
+    TimingDataSource = TimingDataSource
+  }
+}
+`
+	uri := "file://app_inc.marte"
+
+	// 1. Open
+	lsp.HandleDidOpen(lsp.DidOpenTextDocumentParams{
+		TextDocument: lsp.TextDocumentItem{URI: uri, Text: content},
+	})
+
+	out := buf.String()
+
+	// Signal A is never produced. Should have consumed error.
+	if !strings.Contains(out, "ERROR: INOUT Signal 'A'") {
+		t.Error("Missing consumed error for A")
+	}
+	// Signal B is Output, never consumed.
+	if !strings.Contains(out, "WARNING: INOUT Signal 'B'") {
+		t.Error("Missing produced error for B")
+	}
+
+	buf.Reset()
+
+	// 2. Insert comment at start
+	// Expecting same errors
+	change1 := lsp.TextDocumentContentChangeEvent{
+		Range: &lsp.Range{Start: lsp.Position{Line: 0, Character: 0}, End: lsp.Position{Line: 0, Character: 0}},
+		Text:  "// Comment\n",
+	}
+	lsp.HandleDidChange(lsp.DidChangeTextDocumentParams{
+		TextDocument:   lsp.VersionedTextDocumentIdentifier{URI: uri},
+		ContentChanges: []lsp.TextDocumentContentChangeEvent{change1},
+	})
+
+	out = buf.String()
+	// Signal A is never produced. Should have consumed error.
+	if !strings.Contains(out, "ERROR: INOUT Signal 'A'") {
+		t.Error("Missing consumed error for A")
+	}
+	// Signal B is Output, never consumed.
+	if !strings.Contains(out, "WARNING: INOUT Signal 'B'") {
+		t.Error("Missing produced error for B")
+	}
+
+	buf.Reset()
+
+	// 3. Add Value to A
+	currentText := lsp.Documents[uri]
+	idx := strings.Index(currentText, "Placeholder")
+	if idx == -1 {
+		t.Fatal("Could not find anchor string")
+	}
+
+	idx = strings.Index(currentText[idx:], "\n") + idx
+	insertPos := idx + 1
+
+	line, char := offsetToLineChar(currentText, insertPos)
+
+	change2 := lsp.TextDocumentContentChangeEvent{
+		Range: &lsp.Range{Start: lsp.Position{Line: line, Character: char}, End: lsp.Position{Line: line, Character: char}},
+		Text:  "Value = 10\n",
+	}
+
+	lsp.HandleDidChange(lsp.DidChangeTextDocumentParams{
+		TextDocument:   lsp.VersionedTextDocumentIdentifier{URI: uri},
+		ContentChanges: []lsp.TextDocumentContentChangeEvent{change2},
+	})
+
+	out = buf.String()
+
+	// Signal A has now a Value field and so it is produced. Should NOT have consumed error.
+	if strings.Contains(out, "ERROR: INOUT Signal 'A'") {
+		t.Error("Unexpected consumed error for A")
+	}
+	// Signal B is Output, never consumed.
+	if !strings.Contains(out, "WARNING: INOUT Signal 'B'") {
+		t.Error("Missing produced error for B")
+	}
+
+}