Missing space before extends/implements using ClassDeclaration#withExtends/withImplements

[MBoegers]

What version of OpenRewrite are you using?

I am using https://github.com/openrewrite/rewrite Branch: main Commit: 9d567a3

How are you running OpenRewrite?

I wrote a reproducing test.

What is the smallest, simplest way to reproduce the problem?

Find a reproducer test here https://gist.github.com/MBoegers/072b1412e9fee01b4728a61e68f44562

What did you expect to see?

Extending a class with java.util.ArrayList:
Input:

class CustomList {}

Result:

class CustomList extends java.util.ArrayList {}

A class implementing java.io.Serializable:
Input:

class CustomList {}

Result:

class CustomList implements java.io.Serializable {}

What did you see instead?

Extending a class with java.util.ArrayList:

class CustomListextends java.util.ArrayList {}

A class implementing java.io.Serializable:

class CustomListimplements java.io.Serializable {}

What is the full stack trace of any errors you encountered?

Extending a class with java.util.ArrayList:

SLF4J: Failed to load class "org.slf4j.impl.StaticLoggerBinder".
SLF4J: Defaulting to no-operation (NOP) logger implementation
SLF4J: See http://www.slf4j.org/codes.html#StaticLoggerBinder for further details.

[Unexpected result in "de/example/CustomList.java"
diff --git a/de/example/CustomList.java b/de/example/CustomList.java
index e454a71..a71d73b 100644
--- a/de/example/CustomList.java
+++ b/de/example/CustomList.java
@@ -1,4 +1,4 @@ 
 package de.example;
 
-class CustomList extends java.util.ArrayList {
+class CustomListextends java.util.ArrayList {
 }
\ No newline at end of file
] 
expected: 
  "package de.example;
  
  class CustomList extends java.util.ArrayList {
  }"
 but was: 
  "package de.example;
  
  class CustomListextends java.util.ArrayList {
  }"
org.opentest4j.AssertionFailedError: [Unexpected result in "de/example/CustomList.java"
diff --git a/de/example/CustomList.java b/de/example/CustomList.java
index e454a71..a71d73b 100644
--- a/de/example/CustomList.java
+++ b/de/example/CustomList.java
@@ -1,4 +1,4 @@ 
 package de.example;
 
-class CustomList extends java.util.ArrayList {
+class CustomListextends java.util.ArrayList {
 }
\ No newline at end of file
] 
expected: 
  "package de.example;
  
  class CustomList extends java.util.ArrayList {
  }"
 but was: 
  "package de.example;
  
  class CustomListextends java.util.ArrayList {
  }"
	at app//org.openrewrite.test.RewriteTest.rewriteRun(RewriteTest.java:446)
	at app//org.openrewrite.test.RewriteTest.rewriteRun(RewriteTest.java:130)
	at app//org.openrewrite.test.RewriteTest.rewriteRun(RewriteTest.java:125)
	at app//org.openrewrite.java.tree.WithMissPaddingReproducer$WithExtendsTest.triggerIt(WithMissPaddingReproducer.java:90)

A class implementing java.io.Serializable:

SLF4J: Failed to load class "org.slf4j.impl.StaticLoggerBinder".
SLF4J: Defaulting to no-operation (NOP) logger implementation
SLF4J: See http://www.slf4j.org/codes.html#StaticLoggerBinder for further details.

[Unexpected result in "de/example/CustomList.java"
diff --git a/de/example/CustomList.java b/de/example/CustomList.java
index 5be0342..4514ef4 100644
--- a/de/example/CustomList.java
+++ b/de/example/CustomList.java
@@ -1,4 +1,4 @@ 
 package de.example;
 
-class CustomList implements java.io.Serializable {
+class CustomListimplements java.io.Serializable {
 }
\ No newline at end of file
] 
expected: 
  "package de.example;
  
  class CustomList implements java.io.Serializable {
  }"
 but was: 
  "package de.example;
  
  class CustomListimplements java.io.Serializable {
  }"
org.opentest4j.AssertionFailedError: [Unexpected result in "de/example/CustomList.java"
diff --git a/de/example/CustomList.java b/de/example/CustomList.java
index 5be0342..4514ef4 100644
--- a/de/example/CustomList.java
+++ b/de/example/CustomList.java
@@ -1,4 +1,4 @@ 
 package de.example;
 
-class CustomList implements java.io.Serializable {
+class CustomListimplements java.io.Serializable {
 }
\ No newline at end of file
] 
expected: 
  "package de.example;
  
  class CustomList implements java.io.Serializable {
  }"
 but was: 
  "package de.example;
  
  class CustomListimplements java.io.Serializable {
  }"
	at app//org.openrewrite.test.RewriteTest.rewriteRun(RewriteTest.java:446)
	at app//org.openrewrite.test.RewriteTest.rewriteRun(RewriteTest.java:130)
	at app//org.openrewrite.test.RewriteTest.rewriteRun(RewriteTest.java:125)
	at app//org.openrewrite.java.tree.WithMissPaddingReproducer$WithImplementsTest.triggerIt(WithMissPaddingReproducer.java:119)

Are you interested in contributing a fix to OpenRewrite?

Maybe after my current PR.

[timtebeek]

I'm inclined to think this is more likely an issue with openrewrite/rewrite rather than openrewrite/rewrite-migrate-java; what made you open the issue here @MBoegers ?

[MBoegers]

Yes you are right! I just discovered it while developing within openrewrite/rewrite-migrate-java. I can reopen one in openrewrite/rewrite

…

________________________________ Von: Tim te Beek ***@***.***> Gesendet: Friday, June 2, 2023 2:17:48 PM An: openrewrite/rewrite-migrate-java ***@***.***> Cc: Merlin Bögershausen ***@***.***>; Mention ***@***.***> Betreff: Re: [openrewrite/rewrite-migrate-java] Missing space before extends/implements using ClassDeclaration#withExtends/withImplements (Issue openrewrite/rewrite#3289) I'm inclined to think this is more likely an issue with openrewrite/rewrite rather than openrewrite/rewrite-migrate-java; what made you open the issue here @MBoegers<https://github.com/MBoegers> ? — Reply to this email directly, view it on GitHub<#3289>, or unsubscribe<https://github.com/notifications/unsubscribe-auth/ABZVCFLTJ2GBWEWKHZNSSWLXJHKWZANCNFSM6AAAAAAYYHFMHY>. You are receiving this because you were mentioned.Message ID: ***@***.***>

[timtebeek]

No need to reopen; I've just transferred the issue; thanks again for the detailed report! This is really helpful.

[SamantaTarun]

I'd like to work on it.

[timtebeek]

Appreciate the offer to help @tarunsamanta2k20 ! Feel free to start a draft pull request with the above replicating test early. That way you (and I) can step through with the debugger.

[SamantaTarun]

@timtebeek could you please let me know in which file do i have to make changes?

[timtebeek]

You can add the tests that @MBoegers has provided in https://gist.github.com/MBoegers/072b1412e9fee01b4728a61e68f44562 to the bottom of ClassDeclarationTest.java as a start. Then you can already open a draft pull request to replicate the issue here, and then we can start stepping through with the debugger to see what causes the issue. I'm suspecting a lack of padding or prefix to the initial implents or extends.

[timtebeek]

Having briefly explored the issue here I think we might need to make this change to fix the issue for withImplements/withExtends, but I'm uncertain if that will cause any other issues. We'll have to find out on your branch!

diff --git a/rewrite-java/src/main/java/org/openrewrite/java/tree/JContainer.java b/rewrite-java/src/main/java/org/openrewrite/java/tree/JContainer.java
index c0316ea16..0b5642727 100644
--- a/rewrite-java/src/main/java/org/openrewrite/java/tree/JContainer.java
+++ b/rewrite-java/src/main/java/org/openrewrite/java/tree/JContainer.java
@@ -158,7 +158,7 @@ public static <J2 extends J> JContainer<J2> withElementsNullable(@Nullable JCont
             if (elements == null || elements.isEmpty()) {
                 return null;
             }
-            return JContainer.build(Space.EMPTY, JRightPadded.withElements(emptyList(), elements), Markers.EMPTY);
+            return JContainer.build(Space.SINGLE_SPACE, JRightPadded.withElements(emptyList(), elements), Markers.EMPTY);
         }
         if (elements == null || elements.isEmpty()) {
             return null;