2 files changed, 31 insertions, 0 deletions
diff --git a/chapter28b/src/test/java/com/seaofnodes/simple/IncrementalBuildTest.java b/chapter28b/src/test/java/com/seaofnodes/simple/IncrementalBuildTest.java
index 3c53c004..d8f7ef34 100644
--- a/chapter28b/src/test/java/com/seaofnodes/simple/IncrementalBuildTest.java
+++ b/chapter28b/src/test/java/com/seaofnodes/simple/IncrementalBuildTest.java
@@ -10,6 +10,21 @@ import org.junit.Test;
 import static org.junit.Assert.*;
 
 public class IncrementalBuildTest {
+    @Test public void testRequiredTypesBelongToTheirSource() throws Exception {
+        Path base = Path.of("build/objs/incremental");
+        Files.createDirectories(base);
+        Path root = Files.createTempDirectory(base,"required-types-");
+        Path src = Files.createDirectory(root.resolve("src")), obj = Files.createDirectory(root.resolve("obj"));
+        write(src,"App","val marker = 0;",1000);
+        write(src,"App/Main","return A.x+C.y;",1000);
+        write(src,"App/A","int x = 0; val readB = { B b -> b.x; };",1000);
+        write(src,"App/B","int x = 0;",1000);
+        write(src,"App/C","int y = 0;",1000);
+        CodeGen code = new CodeGen(src.toString(),obj.toString(),null,"App/Main",null,123,true,TypeInteger.BOT)
+            .parse();
+        ParseAllTestSupport.checkRequiredTypes(code);
+    }
+
     @Test public void testTransitiveSourceChange() throws Exception {
         Path base=Path.of("build/objs/incremental");
         Files.createDirectories(base);
diff --git a/chapter28b/src/test/java/com/seaofnodes/simple/codegen/ParseAllTestSupport.java b/chapter28b/src/test/java/com/seaofnodes/simple/codegen/ParseAllTestSupport.java
new file mode 100644
index 00000000..2ce97a8e
--- /dev/null
+++ b/chapter28b/src/test/java/com/seaofnodes/simple/codegen/ParseAllTestSupport.java
@@ -0,0 +1,16 @@
+package com.seaofnodes.simple.codegen;
+
+import static org.junit.Assert.*;
+
+public class ParseAllTestSupport {
+    public static void checkRequiredTypes(CodeGen code) {
+        CompUnit a = code._compunits.get("App/A");
+        CompUnit b = code._compunits.get("App/B");
+        CompUnit c = code._compunits.get("App/C");
+        assertNotNull(b);
+        assertTrue(a._deps.find(b)!=-1);
+        // C was parsed after A, while B's layout was still unresolved.
+        // Only A used that layout; C must not inherit A's build dependency.
+        assertNull(c._deps);
+    }
+}