Add a couple build tests.

src/ast/mod.rs

@@ -56,7 +56,6 @@ pub mod build {
 
     #[cfg(test)]
     mod build_tests {
-        use std::process::id;
         use super::*;
         use crate::parser::DeimosParser;
         use pest::Parser;
@@ -109,5 +108,26 @@ pub mod build {
             let pair = parse(Rule::DStringExpression, "${thing}");
             let d_string_expression = build_d_string_expression(pair);
         }
+
+        #[test]
+        fn d_string_inner() {
+            let pair = parse(Rule::DStringInner, "Hello!");
+            let d_string_inner = build_d_string_inner(pair);
+            assert_eq!("Hello!", d_string_inner);
+        }
+
+        #[test]
+        fn d_string_mixed() {
+            let pair = parse(Rule::DString, "\"Hello, ${world}!\"");
+            let d_string = build_d_string(pair);
+            assert_eq!(d_string.inners().count(), 2);
+            assert_eq!(d_string.expressions().count(), 1);
+        }
+
+        #[test]
+        fn expression_simple_call() {
+            let pair = parse(Rule::Expression, "hello(42)");
+            let expression = build_expression(pair);
+        }
     }
 }