Add a unit test for the precedence expression parsers

crates/solidity/outputs/cargo/tests/src/lib.rs

@@ -3,5 +3,6 @@
 mod cst_output;
 mod doc_examples;
 mod errors;
+mod parser;
 mod scanner;
 mod versions;

crates/solidity/outputs/cargo/tests/src/parser/mod.rs

@@ -0,0 +1,29 @@
+use semver::Version;
+use slang_solidity::{kinds::RuleKind, language::Language};
+
+#[test]
+fn test_precedence_expression() {
+    let language = Language::new(Version::new(0, 8, 0)).unwrap();
+
+    let output = language.parse(RuleKind::ShiftExpression, "1 >> 2");
+    assert!(output.is_valid());
+    let output = language.parse(RuleKind::ShiftExpression, "1 + 2");
+    assert!(!output.is_valid());
+    let output = language.parse(RuleKind::ArrayTypeName, "uint[]");
+    assert!(output.is_valid());
+
+    // Plus prefix was removed in 0.5.0
+    let language = Language::new(Version::new(0, 4, 11)).unwrap();
+    let output = language.parse(RuleKind::PrefixExpression, "+1");
+    assert!(output.is_valid());
+    let language = Language::new(Version::new(0, 8, 0)).unwrap();
+    let output = language.parse(RuleKind::PrefixExpression, "+1");
+    assert!(!output.is_valid());
+
+    // Changed to right-associative in 0.6.0; the rule should still be valid
+    let output = language.parse(RuleKind::ExponentiationExpression, "1 ** 2");
+    assert!(output.is_valid());
+    let language = Language::new(Version::new(0, 5, 0)).unwrap();
+    let output = language.parse(RuleKind::ExponentiationExpression, "1 ** 2");
+    assert!(output.is_valid());
+}