[fine] Dump CSTs and an example zoo

fine/tests/example_tests.rs

@@ -0,0 +1,8 @@
+use fine::parser::concrete::Tree;
+use pretty_assertions::assert_eq;
+
+fn assert_concrete(tree: &Tree, expected: &str) {
+    assert_eq!(tree.dump(), expected, "concrete syntax trees did not match");
+}
+
+include!(concat!(env!("OUT_DIR"), "/generated_tests.rs"));

fine/tests/expression/expressions.fine

@@ -0,0 +1,27 @@
+// concrete:
+// | File
+// |   ExpressionStatement
+// |     LiteralExpression
+// |       Number:'"42"'
+// |     Semicolon:'";"'
+// |   ExpressionStatement
+// |     BinaryExpression
+// |       BinaryExpression
+// |         LiteralExpression
+// |           Number:'"1"'
+// |         Star:'"*"'
+// |         LiteralExpression
+// |           Number:'"2"'
+// |       Plus:'"+"'
+// |       BinaryExpression
+// |         UnaryExpression
+// |           Minus:'"-"'
+// |           LiteralExpression
+// |             Number:'"3"'
+// |         Star:'"*"'
+// |         LiteralExpression
+// |           Number:'"4"'
+// |     Semicolon:'";"'
+//
+42;
+1 * 2 + -3 * 4;