config: Append supports `terraform`

config/append.go

@@ -35,6 +35,11 @@ func Append(c1, c2 *Config) (*Config, error) {
 		c.Atlas = c2.Atlas
 	}
 
+	c.Terraform = c1.Terraform
+	if c2.Terraform != nil {
+		c.Terraform = c2.Terraform
+	}
+
 	if len(c1.Modules) > 0 || len(c2.Modules) > 0 {
 		c.Modules = make(
 			[]*Module, 0, len(c1.Modules)+len(c2.Modules))

config/append_test.go

@@ -87,6 +87,37 @@ func TestAppend(t *testing.T) {
 
 			false,
 		},
+
+		// Terraform block
+		{
+			&Config{
+				Terraform: &Terraform{
+					RequiredVersion: "A",
+				},
+			},
+			&Config{},
+			&Config{
+				Terraform: &Terraform{
+					RequiredVersion: "A",
+				},
+			},
+			false,
+		},
+
+		{
+			&Config{},
+			&Config{
+				Terraform: &Terraform{
+					RequiredVersion: "A",
+				},
+			},
+			&Config{
+				Terraform: &Terraform{
+					RequiredVersion: "A",
+				},
+			},
+			false,
+		},
 	}
 
 	for i, tc := range cases {