Flowchart title double quotes

README.md

@@ -52,7 +52,7 @@ Will generate the following Mermaid output:
 
 ```mermaid
 ---
-title: Basic usage
+title: "Basic usage"
 ---
 flowchart TD
   start["Start"]
@@ -183,7 +183,7 @@ Will generate the following Mermaid output:
 
 ```mermaid
 ---
-title: Various node shapes
+title: "Various node shapes"
 ---
 flowchart TD
   rectangle["Rectangle"]
@@ -247,7 +247,7 @@ Will generate the following Mermaid output:
 
 ```mermaid
 ---
-title: Link types
+title: "Link types"
 ---
 flowchart TD
   a["A"]
@@ -308,7 +308,7 @@ Will generate the following Mermaid output:
 
 ```mermaid
 ---
-title: Using subgraphs
+title: "Using subgraphs"
 ---
 flowchart TD
   n["Node"]
@@ -373,7 +373,7 @@ Will generate the following Mermaid output:
 
 ```mermaid
 ---
-title: Styling nodes
+title: "Styling nodes"
 ---
 flowchart TD
   a["A"]
@@ -427,7 +427,7 @@ Will generate the following Mermaid output:
 
 ```mermaid
 ---
-title: Styling links
+title: "Styling links"
 ---
 flowchart TD
   a["A"]

src/Mermaid.Flowcharts/FlowchartTitle.cs

@@ -32,7 +32,7 @@ public static FlowchartTitle FromString(string text)
             throw new ArgumentException("Flowchart title must not be whitespace.", nameof(text));
         }
 
-        return new(text);
+        return new(text.Replace("\"", "\\\""));
     }
 
     public override string ToString()
@@ -43,7 +43,7 @@ public string ToMermaidString(int indentations = 0, string indentationText = "
         StringBuilder flowchartTitleBuilder = new();
         flowchartTitleBuilder
             .AppendLine($"{indentationText.Repeat(indentations)}---")
-            .AppendLine($"{indentationText.Repeat(indentations)}title: {Text}")
+            .AppendLine($"{indentationText.Repeat(indentations)}title: \"{Text}\"")
             .Append($"{indentationText.Repeat(indentations)}---");
         return flowchartTitleBuilder.ToString();
     }

src/Mermaid.Flowcharts/Nodes/NodeIdentifier.cs

@@ -28,24 +28,24 @@ public static NodeIdentifier Create()
 
     public static NodeIdentifier FromString(string text)
     {
-        if (text.StartsWith('_') || text.StartsWith('.') || text.StartsWith('-'))
+        if (string.IsNullOrEmpty(text))
         {
-            throw new ArgumentException("Identifier must not start with a separator.", nameof(text));
+            throw new ArgumentException("Identifier must not be empty.", nameof(text));
         }
 
-        if (text.EndsWith('_') || text.EndsWith('.') || text.EndsWith('-'))
+        if (string.IsNullOrWhiteSpace(text))
         {
-            throw new ArgumentException("Identifier must not end with a separator.", nameof(text));
+            throw new ArgumentException("Identifier must not be whitespace.", nameof(text));
         }
 
-        if (string.IsNullOrEmpty(text))
+        if (text.StartsWith('_') || text.StartsWith('.') || text.StartsWith('-'))
         {
-            throw new ArgumentException("Identifier must not be empty.", nameof(text));
+            throw new ArgumentException("Identifier must not start with a separator.", nameof(text));
         }
 
-        if (string.IsNullOrWhiteSpace(text))
+        if (text.EndsWith('_') || text.EndsWith('.') || text.EndsWith('-'))
         {
-            throw new ArgumentException("Identifier must not be whitespace.", nameof(text));
+            throw new ArgumentException("Identifier must not end with a separator.", nameof(text));
         }
 
         bool containsDisallowedValue = text.AsSpan().IndexOfAnyExcept(AllowedCharacters) > -1;

tests/Mermaid.Flowcharts.Tests/FlowchartTitleTests.cs

@@ -75,7 +75,14 @@ public void Title_ShouldThrow_WhenNewline(string newline)
         'a',
         """
         ---
-        title: a
+        title: "a"
+        ---
+        """)]
+    [InlineData(
+        '"',
+        """
+        ---
+        title: "\""
         ---
         """)]
     public void Title_ShouldToMermaidString_SingleLetter(char letter, string expected)
@@ -98,7 +105,17 @@ public void Title_ShouldToMermaidString_SingleLetter(char letter, string expecte
         "  ",
         """
             ---
-            title: a
+            title: "a"
+            ---
+        """
+    )]
+    [InlineData(
+        '"',
+        2,
+        "  ",
+        """
+            ---
+            title: "\""
             ---
         """
     )]

tests/Mermaid.Flowcharts.Tests/ReadmeTests.cs

@@ -38,7 +38,7 @@ public void BasicUsage()
         string expected =
             """
             ---
-            title: Basic usage
+            title: "Basic usage"
             ---
             flowchart TD
               start["Start"]
@@ -98,7 +98,7 @@ public void VariousNodeShapes()
         string expected =
             """
             ---
-            title: Various node shapes
+            title: "Various node shapes"
             ---
             flowchart TD
               rectangle["Rectangle"]
@@ -156,7 +156,7 @@ public void LinkTypes()
         string expected =
             """
             ---
-            title: Link types
+            title: "Link types"
             ---
             flowchart TD
               a["A"]
@@ -210,7 +210,7 @@ public void UsingSubgraphs()
         string expected =
             """
             ---
-            title: Using subgraphs
+            title: "Using subgraphs"
             ---
             flowchart TD
               n["Node"]
@@ -258,7 +258,7 @@ public void StylingNodes()
         string expected =
             """
             ---
-            title: Styling nodes
+            title: "Styling nodes"
             ---
             flowchart TD
               a["A"]
@@ -306,7 +306,7 @@ public void StylingLinks()
         string expected =
             """
             ---
-            title: Styling links
+            title: "Styling links"
             ---
             flowchart TD
               a["A"]