Fix removing substitutions that are still to be resolved (#142)

* Added failing test

* Fixed related test

* Fixed removing of valid substitutions

Author: IgorFedchenko

src/Hocon.Tests/HoconTests.cs

@@ -9,6 +9,7 @@
 using System.Collections.Generic;
 using System.Linq;
 using System.Threading.Tasks;
+using FluentAssertions;
 using Xunit;
 using Xunit.Abstractions;
 
@@ -326,6 +327,37 @@ public void CanAssignValuesToPathExpressions()
             Assert.Equal(3L, config.GetLong("a.b.e.f"));
         }
 
+        [Fact]
+        public void Fix_substitutions_Issue123()
+        {
+            var hocon = @"
+a: avalue
+
+b {
+  b1: ""0001-01-01Z""
+  b2: 0
+  b_alpha: ${a}/${c.c1}/${b.b3}/${b.b4}
+  b_beta: ""[""${b.b_alpha}"",""${b.b1}"",""${b.b2}""]""
+}
+
+c {
+  c1: c1value
+}
+
+b {
+  b3: b4value
+}
+
+b {
+  b4: b4value
+}
+";
+
+            var config = Parser.Parse(hocon);
+            config.GetString("b.b_alpha").Should().Be("avalue/c1value/b4value/b4value");
+            config.GetString("b.b_beta").Should().Be("[avalue/c1value/b4value/b4value,0001-01-01Z,0]");
+        }
+
         [Fact]
         public void CanAssignLongToField()
         {

src/Hocon.Tests/SelfReferentialSubstitution.cs

@@ -186,7 +186,10 @@ public void HiddenSubstitutionShouldNeverBeEvaluated()
         {
             var hocon = @"
 foo : ${does-not-exist}
-foo : 42";
+foo : 42
+bar : ${yet-another-to-ignore}
+bar : [42]
+";
 
             HoconRoot config = null;
             var ex = Record.Exception(() => config = Parser.Parse(hocon));

src/Hocon/Impl/HoconField.cs

@@ -96,12 +96,13 @@ internal void SetValue(HoconValue value)
             if (value == null)
                 return;
 
-            if (value.Type == HoconType.Literal)
+            if (value.Type != HoconType.Object)
             {
                 foreach (var item in _internalValues)
                 {
                     var subs = item.GetSubstitutions();
-                    foreach (var sub in subs)
+                    var preservedSub = value.GetSubstitutions();
+                    foreach (var sub in subs.Except(preservedSub))
                     {
                         sub.Removed = true;
                     }