From 0c1f2b55c8b6753c128a34acf1a6cb160350e824 Mon Sep 17 00:00:00 2001
From: Michael Williamson <mike@zwobble.org>
Date: Wed, 1 Nov 2023 22:42:06 +0000
Subject: Handle behaviour of if expressions properly

---
 .../parser/ParserExpressionStatementTests.java     | 115 +++++++++++++++++++++
 1 file changed, 115 insertions(+)

(limited to 'src/test/java')

diff --git a/src/test/java/org/shedlang/compiler/parser/ParserExpressionStatementTests.java b/src/test/java/org/shedlang/compiler/parser/ParserExpressionStatementTests.java
index 13698b85..bc414be1 100644
--- a/src/test/java/org/shedlang/compiler/parser/ParserExpressionStatementTests.java
+++ b/src/test/java/org/shedlang/compiler/parser/ParserExpressionStatementTests.java
@@ -1,10 +1,19 @@
 package org.shedlang.compiler.parser;
 
+import org.junit.jupiter.api.Nested;
 import org.junit.jupiter.api.Test;
+import org.shedlang.compiler.ast.untyped.Untyped;
+import org.shedlang.compiler.ast.untyped.UntypedBlockNode;
+import org.shedlang.compiler.ast.untyped.UntypedFunctionStatementBehaviour;
+import org.shedlang.compiler.parser.errors.InconsistentBlockBehaviourError;
 
+import java.util.List;
+
+import static org.junit.jupiter.api.Assertions.assertThrows;
 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.equalTo;
 import static org.zwobble.precisely.Matchers.isSequence;
 
 public class ParserExpressionStatementTests {
@@ -82,4 +91,110 @@ public class ParserExpressionStatementTests {
             )
         ));
     }
+
+    @Nested
+    public class BranchBehaviourTests {
+        @Test
+        public void whenAllBranchesContinueThenExpressionStatementContinues() {
+            var blocks = List.of(
+                blockWithBehaviour(UntypedFunctionStatementBehaviour.CONTINUE),
+                blockWithBehaviour(UntypedFunctionStatementBehaviour.CONTINUE)
+            );
+
+            var result = Parser.expressionStatementBehaviour(blocks);
+
+            assertThat(result, equalTo(UntypedFunctionStatementBehaviour.CONTINUE));
+        }
+
+        @Test
+        public void whenAllBranchesBlockThenExpressionStatementBlockReturns() {
+            var blocks = List.of(
+                blockWithBehaviour(UntypedFunctionStatementBehaviour.BLOCK_RETURN),
+                blockWithBehaviour(UntypedFunctionStatementBehaviour.BLOCK_RETURN)
+            );
+
+            var result = Parser.expressionStatementBehaviour(blocks);
+
+            assertThat(result, equalTo(UntypedFunctionStatementBehaviour.BLOCK_RETURN));
+        }
+
+        @Test
+        public void whenAllBranchesTerminateThenExpressionStatementTerminates() {
+            var blocks = List.of(
+                blockWithBehaviour(UntypedFunctionStatementBehaviour.TERMINATE),
+                blockWithBehaviour(UntypedFunctionStatementBehaviour.TERMINATE)
+            );
+
+            var result = Parser.expressionStatementBehaviour(blocks);
+
+            assertThat(result, equalTo(UntypedFunctionStatementBehaviour.TERMINATE));
+        }
+
+        @Test
+        public void whenBranchesTerminateOrContinueThenExpressionStatementContinues() {
+            var blocks = List.of(
+                blockWithBehaviour(UntypedFunctionStatementBehaviour.TERMINATE),
+                blockWithBehaviour(UntypedFunctionStatementBehaviour.CONTINUE),
+                blockWithBehaviour(UntypedFunctionStatementBehaviour.TERMINATE)
+            );
+
+            var result = Parser.expressionStatementBehaviour(blocks);
+
+            assertThat(result, equalTo(UntypedFunctionStatementBehaviour.CONTINUE));
+        }
+
+        @Test
+        public void whenBranchesTerminateOrBlockReturnThenExpressionStatementBlockReturns() {
+            var blocks = List.of(
+                blockWithBehaviour(UntypedFunctionStatementBehaviour.TERMINATE),
+                blockWithBehaviour(UntypedFunctionStatementBehaviour.BLOCK_RETURN),
+                blockWithBehaviour(UntypedFunctionStatementBehaviour.TERMINATE)
+            );
+
+            var result = Parser.expressionStatementBehaviour(blocks);
+
+            assertThat(result, equalTo(UntypedFunctionStatementBehaviour.BLOCK_RETURN));
+        }
+
+        @Test
+        public void whenBranchesContinueOrBlockReturnThenErrorIsThrown() {
+            var blocks = List.of(
+                blockWithBehaviour(UntypedFunctionStatementBehaviour.CONTINUE),
+                blockWithBehaviour(UntypedFunctionStatementBehaviour.BLOCK_RETURN)
+            );
+
+            assertThrows(
+                InconsistentBlockBehaviourError.class,
+                () -> Parser.expressionStatementBehaviour(blocks)
+            );
+        }
+
+        @Test
+        public void whenThereAreNoBranchesThenExpressionStatementTerminates() {
+            var blocks = List.<UntypedBlockNode>of();
+
+            var result = Parser.expressionStatementBehaviour(blocks);
+
+            assertThat(result, equalTo(UntypedFunctionStatementBehaviour.TERMINATE));
+        }
+
+        private UntypedBlockNode blockWithBehaviour(UntypedFunctionStatementBehaviour behaviour) {
+            var statement = switch (behaviour) {
+                case TERMINATE ->
+                    Untyped.functionReturn(Untyped.intLiteral(0));
+
+                case BLOCK_RETURN ->
+                    Untyped.blockReturn(Untyped.intLiteral(0));
+
+                case CONTINUE ->
+                    Untyped.expressionStatement(Untyped.intLiteral(0));
+            };
+
+            var block = Untyped.block(List.of(statement));
+
+            assertThat(block.behaviour(), equalTo(behaviour));
+
+            return block;
+        }
+    }
 }
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