Parse when expressions

2 files changed, 62 insertions, 0 deletions

diff --git a/src/test/java/org/shedlang/compiler/ast/untyped/UntypedNodeMatchers.java b/src/test/java/org/shedlang/compiler/ast/untyped/UntypedNodeMatchers.java
index ddb7db96..fdbb8f53 100644
--- a/src/test/java/org/shedlang/compiler/ast/untyped/UntypedNodeMatchers.java
+++ b/src/test/java/org/shedlang/compiler/ast/untyped/UntypedNodeMatchers.java
@@ -279,6 +279,27 @@ public class UntypedNodeMatchers {
         );
     }
 
+    public static Matcher<UntypedExpressionNode> isUntypedWhenNode(
+        Matcher<UntypedExpressionNode> expression,
+        Matcher<Iterable<? extends UntypedWhenCaseNode>> cases
+    ) {
+        return instanceOf(
+            UntypedWhenNode.class,
+            has("expression", x -> x.expression(), expression),
+            has ("cases", x -> x.cases(), cases)
+        );
+    }
+
+    public static Matcher<UntypedWhenCaseNode> isUntypedWhenCaseNode(
+        Matcher<UntypedTypeLevelExpressionNode> caseType,
+        Matcher<UntypedBlockNode> body
+    ) {
+        return allOf(
+            has("caseType", x -> x.caseType(), caseType),
+            has("body", x -> x.body(), body)
+        );
+    }
+
     public static Matcher<UntypedFunctionStatementNode> isUntypedWhileNode(
         Matcher<UntypedExpressionNode> condition,
         Matcher<UntypedBlockNode> body
diff --git a/src/test/java/org/shedlang/compiler/parser/ParserWhenTests.java b/src/test/java/org/shedlang/compiler/parser/ParserWhenTests.java
new file mode 100644
index 00000000..709d7cce
--- /dev/null
+++ b/src/test/java/org/shedlang/compiler/parser/ParserWhenTests.java
@@ -0,0 +1,41 @@
+package org.shedlang.compiler.parser;
+
+import org.junit.jupiter.api.Test;
+
+import static org.shedlang.compiler.ast.untyped.UntypedNodeMatchers.*;
+import static org.shedlang.compiler.parser.ParserTesting.parseString;
+import static org.zwobble.precisely.AssertThat.assertThat;
+import static org.zwobble.precisely.Matchers.isSequence;
+
+public class ParserWhenTests {
+    @Test
+    public void canParseWhen() {
+        var source = """
+            when (x) {
+                is A {
+                    return 4;
+                }
+                is B {
+                }
+            }
+        """;
+
+        var node = parseString(source, Parser::parseTopLevelExpression);
+
+        assertThat(node, isUntypedWhenNode(
+            isUntypedReferenceNode("x"),
+            isSequence(
+                isUntypedWhenCaseNode(
+                    isUntypedTypeLevelReferenceNode("A"),
+                    isUntypedBlockNode(isSequence(
+                        isUntypedFunctionReturnNode(isUntypedIntLiteralNode(4))
+                    ))
+                ),
+                isUntypedWhenCaseNode(
+                    isUntypedTypeLevelReferenceNode("B"),
+                    isUntypedBlockNode(isSequence())
+                )
+            )
+        ));
+    }
+}