Support for an embedded expression in variable value node

src/Microsoft.DotNet.Interactive.Http.Parsing/Parsing/HttpRequestParser.cs

@@ -131,6 +131,15 @@ public HttpSyntaxTree Parse()
                         node = new HttpVariableValueNode(_sourceText, _syntaxTree);
 
                         ParseLeadingWhitespaceAndComments(node);
+                    } 
+                    else if (IsAtStartOfEmbeddedExpression())
+                    {
+                        node = new HttpVariableValueNode(_sourceText, _syntaxTree);
+                        node.Add(ParseEmbeddedExpression());
+                        if(CurrentToken is { Kind: HttpTokenKind.NewLine })
+                        {
+                            break;
+                        }
                     }
                     else
                     {

src/Microsoft.DotNet.Interactive.Http.Tests/ParserTests.Request.cs

@@ -64,6 +64,32 @@ public void request_node_containing_only_url_and_no_variable_expressions_returns
             bindingResult.Value.Method.Should().Be(HttpMethod.Get);
         }
 
+        [Fact]
+        public void request_node_with_multiple_variables_declared_prior_parsed_correctly()
+        {
+            var result = Parse(
+                """
+                @searchTerm=some-search-term
+                @hostname=httpbin.org
+                # variable using another variable
+                @host=https://{{hostname}}
+                # variable using "dynamic variables"
+                @createdAt = {{$datetime iso8601}}
+                @anyhost={{host}}/anything
+                @fakeuser=fakeuser
+                @fakepwd=fakepwd
+
+                https://httpbin.org/get
+                """);
+
+            var requestNode = result.SyntaxTree.RootNode.ChildNodes.Should().ContainSingle<HttpRequestNode>().Which;
+
+            var variableNodes = result.SyntaxTree.RootNode.ChildNodes.OfType<HttpVariableDeclarationAndAssignmentNode>();
+            variableNodes.Count().Should().Be(7);
+
+            requestNode.UrlNode.Text.Should().Be("https://httpbin.org/get");
+        }
+
         [Fact]
         public void request_node_containing_method_and_url_and_no_variable_expressions_returns_HttpRequestMessage_with_specified_method()
         {