Support nullable attributes

TerraformPluginDotNet.Test/Functional/TerraformResourceTest.cs

@@ -71,4 +71,36 @@ public async Task TestPlanCreateAllFields()
 
         Assert.That(after, Is.EqualTo(expected));
     }
+
+    [Test]
+    public async Task TestPlanCreateOnlyRequiredFields()
+    {
+        using var terraform = await _host.CreateTerraformTestInstanceAsync(ProviderName);
+
+        var resourcePath = Path.Combine(terraform.WorkDir, "file.tf");
+
+        await File.WriteAllTextAsync(resourcePath, $@"
+resource ""test_resource"" ""test"" {{
+  required_attribute = ""value""
+}}
+");
+
+        var plan = await terraform.PlanWithOutputAsync();
+
+        Assert.That(plan.ResourceChanges, Has.Count.EqualTo(1));
+        Assert.That(plan.ResourceChanges.Single().Change.Actions.Single(), Is.EqualTo("create"));
+        Assert.That(plan.ResourceChanges.Single().Change.Before, Is.Null);
+
+        var after = plan.ResourceChanges.Single().Change.After.ToJsonString(new JsonSerializerOptions() { WriteIndented = true });
+        var expected = @"
+{
+  ""boolean_attribute"": null,
+  ""double_attribute"": null,
+  ""float_attribute"": null,
+  ""int_attribute"": null,
+  ""required_attribute"": ""value""
+}".Trim();
+
+        Assert.That(after, Is.EqualTo(expected));
+    }
 }

TerraformPluginDotNet.Test/TestResource.cs

@@ -23,17 +23,17 @@ public class TestResource
 
     [Key("int_attribute")]
     [Description("Int attribute.")]
-    public int IntAttribute { get; set; }
+    public int? IntAttribute { get; set; }
 
     [Key("boolean_attribute")]
     [Description("A boolean attribute.")]
-    public bool BooleanAttribute { get; set; }
+    public bool? BooleanAttribute { get; set; }
 
     [Key("float_attribute")]
     [Description("A float attribute.")]
-    public float FloatAttribute { get; set; }
+    public float? FloatAttribute { get; set; }
 
     [Key("double_attribute")]
     [Description("A double attribute.")]
-    public float DoubleAttribute { get; set; }
+    public float? DoubleAttribute { get; set; }
 }

TerraformPluginDotNet/Schemas/SchemaBuilder.cs

@@ -41,6 +41,11 @@ public Schema BuildSchema(Type type)
 
     private static string GetTerraformType(Type t)
     {
+        if (t.IsValueType && Nullable.GetUnderlyingType(t) != null)
+        {
+            t = Nullable.GetUnderlyingType(t);
+        }
+
         if (t == typeof(string))
         {
             return "string";