From deee2d3f92e3f09b711e1fc68a25129bc554df2a Mon Sep 17 00:00:00 2001
From: Michael Williamson <mike@zwobble.org>
Date: Fri, 12 Jun 2026 15:43:02 +0100
Subject: Add implementsTypes to JavaClassDeclaration

---
 .../compiler/output/lang/java/JavaWriterTests.java | 96 ++++++++++++++++++++++
 1 file changed, 96 insertions(+)

(limited to 'src/test/java/org/zwobble')

diff --git a/src/test/java/org/zwobble/hobgoblin/compiler/output/lang/java/JavaWriterTests.java b/src/test/java/org/zwobble/hobgoblin/compiler/output/lang/java/JavaWriterTests.java
index 798de28..53a3e65 100644
--- a/src/test/java/org/zwobble/hobgoblin/compiler/output/lang/java/JavaWriterTests.java
+++ b/src/test/java/org/zwobble/hobgoblin/compiler/output/lang/java/JavaWriterTests.java
@@ -23,6 +23,7 @@ public class JavaWriterTests {
             new JavaClassDeclaration(
                 "Rectangle",
                 List.of(),
+                List.of(),
                 new JavaCustomArea(JavaTypeRef.topLevel(List.of(), "Rectangle"), "body"),
                 DocComment.EMPTY
             )
@@ -48,6 +49,7 @@ public class JavaWriterTests {
         var java = new JavaClassDeclaration(
             "Rectangle",
             List.of(),
+            List.of(),
             new JavaCustomArea(JavaTypeRef.topLevel(List.of(), "Rectangle"), "body"),
             DocComment.EMPTY
         );
@@ -62,10 +64,56 @@ public class JavaWriterTests {
         ));
     }
 
+    @Test
+    public void classDeclarationImplementingSingleInterface() throws IOException {
+        var java = new JavaClassDeclaration(
+            "Rectangle",
+            List.of(
+                JavaTypeRef.topLevel(List.of("com.example"), "Shape")
+            ),
+            List.of(),
+            new JavaCustomArea(JavaTypeRef.topLevel(List.of(), "Rectangle"), "body"),
+            DocComment.EMPTY
+        );
+
+        var string = write(writer -> writer.writeTypeDeclaration(java));
+
+        assertThat(string, equalTo("""
+            public class Rectangle implements com.example.Shape {
+                // Custom area start: Rectangle body
+                // Custom area end: Rectangle body
+            }"""
+        ));
+    }
+
+    @Test
+    public void classDeclarationImplementingMultipleInterfaces() throws IOException {
+        var java = new JavaClassDeclaration(
+            "Rectangle",
+            List.of(
+                JavaTypeRef.topLevel(List.of("com.example"), "Shape"),
+                JavaTypeRef.topLevel(List.of("com.example"), "Drawable")
+            ),
+            List.of(),
+            new JavaCustomArea(JavaTypeRef.topLevel(List.of(), "Rectangle"), "body"),
+            DocComment.EMPTY
+        );
+
+        var string = write(writer -> writer.writeTypeDeclaration(java));
+
+        assertThat(string, equalTo("""
+            public class Rectangle implements com.example.Shape, com.example.Drawable {
+                // Custom area start: Rectangle body
+                // Custom area end: Rectangle body
+            }"""
+        ));
+    }
+
     @Test
     public void classDeclarationWithMethods() throws IOException {
         var java = new JavaClassDeclaration(
             "Rectangle",
+            List.of(),
             List.of(
                 new JavaMethodDeclaration(
                     "a",
@@ -107,6 +155,7 @@ public class JavaWriterTests {
         var java = new JavaClassDeclaration(
             "Point",
             List.of(),
+            List.of(),
             new JavaCustomArea(JavaTypeRef.topLevel(List.of(), "Point"), "body"),
             new DocComment("A 2D point.")
         );
@@ -295,6 +344,53 @@ public class JavaWriterTests {
         ));
     }
 
+    @Test
+    public void recordDeclarationImplementingOneInterface() throws IOException {
+        var java = new JavaRecordDeclaration(
+            "Rectangle",
+            List.of(),
+            List.of(
+                JavaTypeRef.topLevel(List.of("com.example"), "Shape")
+            ),
+            List.of(),
+            new JavaCustomArea(JavaTypeRef.topLevel(List.of(), "Rectangle"), "body"),
+            DocComment.EMPTY
+        );
+
+        var string = write(writer -> writer.writeTypeDeclaration(java));
+
+        assertThat(string, equalTo("""
+            public record Rectangle() implements com.example.Shape {
+                // Custom area start: Rectangle body
+                // Custom area end: Rectangle body
+            }"""
+        ));
+    }
+
+    @Test
+    public void recordDeclarationImplementingMultipleInterfaces() throws IOException {
+        var java = new JavaRecordDeclaration(
+            "Rectangle",
+            List.of(),
+            List.of(
+                JavaTypeRef.topLevel(List.of("com.example"), "Shape"),
+                JavaTypeRef.topLevel(List.of("com.example"), "Drawable")
+            ),
+            List.of(),
+            new JavaCustomArea(JavaTypeRef.topLevel(List.of(), "Rectangle"), "body"),
+            DocComment.EMPTY
+        );
+
+        var string = write(writer -> writer.writeTypeDeclaration(java));
+
+        assertThat(string, equalTo("""
+            public record Rectangle() implements com.example.Shape, com.example.Drawable {
+                // Custom area start: Rectangle body
+                // Custom area end: Rectangle body
+            }"""
+        ));
+    }
+
     @Test
     public void recordDeclarationWithMethods() throws IOException {
         var java = new JavaRecordDeclaration(
-- 
cgit v1.2.3