[fine] Tests for conditional, semicolon optional at end of block

Just like rust, ';' means "discard this value".

fine/src/parser/concrete.rs

@@ -422,7 +422,9 @@ fn statement_let(p: &mut CParser) {
     p.expect(TokenKind::Identifier, "expected a name for the variable");
     p.expect(TokenKind::Equal, "expected a '=' after the variable name");
     expression(p);
-    p.expect(TokenKind::Semicolon, "expect ';' to end a let statement");
+    if !p.at(TokenKind::RightBrace) {
+        p.expect(TokenKind::Semicolon, "expect ';' to end a let statement");
+    }
 
     p.end(m, TreeKind::LetStatement);
 }
@@ -436,7 +438,9 @@ fn statement_return(p: &mut CParser) {
         "expect 'return' to start a return statement",
     );
     expression(p);
-    p.expect(TokenKind::Semicolon, "expect ';' to end a return statement");
+    if !p.at(TokenKind::RightBrace) {
+        p.expect(TokenKind::Semicolon, "expect ';' to end a return statement");
+    }
 
     p.end(m, TreeKind::ReturnStatement);
 }
@@ -445,10 +449,12 @@ fn statement_expression(p: &mut CParser) {
     let m = p.start();
 
     expression(p);
-    p.expect(
+    if !p.at(TokenKind::RightBrace) {
-        TokenKind::Semicolon,
+        p.expect(
-        "expect ';' to end an expression statement",
+            TokenKind::Semicolon,
-    );
+            "expect ';' to end an expression statement",
+        );
+    }
 
     p.end(m, TreeKind::ExpressionStatement);
 }

fine/tests/example_tests.rs

@@ -2,13 +2,13 @@ use fine::parser::concrete::Tree;
 use pretty_assertions::assert_eq;
 
 fn rebase_concrete(source_path: &str, dump: &str) {
-    // RE-BASE
     let contents = std::fs::read_to_string(source_path)
         .expect(&format!("unable to read input file {}", source_path));
 
     let mut result = String::new();
     let mut lines = contents.lines();
 
+    // Search for the "concrete:" section.
     let mut found_concrete_section = false;
     while let Some(line) = lines.next() {
         result.push_str(line);
@@ -26,6 +26,8 @@ fn rebase_concrete(source_path: &str, dump: &str) {
         );
     }
 
+    // We've found the section we care about, replace all the lines we care
+    // about with the actual lines.
     let mut replaced_output = false;
     while let Some(line) = lines.next() {
         if line.starts_with("// | ") {

fine/tests/expression/conditional.fine

@@ -0,0 +1,26 @@
+// concrete:
+// | File
+// |   IfStatement
+// |     ConditionalExpression
+// |       If:'"if"'
+// |       LiteralExpression
+// |         True:'"true"'
+// |       Block
+// |         LeftBrace:'"{"'
+// |         ExpressionStatement
+// |           LiteralExpression
+// |             String:'"\"discarded\""'
+// |           Semicolon:'";"'
+// |         ExpressionStatement
+// |           LiteralExpression
+// |             Number:'"23"'
+// |         RightBrace:'"}"'
+// |       Else:'"else"'
+// |       Block
+// |         LeftBrace:'"{"'
+// |         ExpressionStatement
+// |           LiteralExpression
+// |             Number:'"45"'
+// |         RightBrace:'"}"'
+//
+if true { "discarded"; 23 } else { 45 }