Fix attachment rendering (#12)

In Cucumber JVM attachments can be created in a few different ways. How
influences whether the attachment ends up as elements of `embeddings` or
`output`.

| Method                         | Encoding | Media Type                | Destination  |
| ------------------------------ | -------- | ------------------------- | ------------ |
| `Scenario.attach(byte[], ...)` | BASE64   | any, from method          | `embeddings` |
| `Scenario.attach(String, ...)` | IDENTITY | any, from method          | `embeddings` |
| `Scenario.log(String)`         | IDENTITY | text/x.cucumber.log+plain | `output`     |

Originally the implementation determined the destination based on the
encoding, but this is obviously not correct. An alternative would be to
select on the media type.

This does come with the disadvantage that `Scenario.attach` also takes
in a media type argument. So in theory that could be
`text/x.cucumber.log+plain` but for now we'll assume that is not the
case.

Should this assumption prove wrong we could match on both encoding and
media type, but it would be more reasonable for the user to change their
code.

Fixes: cucumber/cucumber-jvm#3069

Author: mpkorstanje

CHANGELOG.md

@@ -6,18 +6,20 @@ The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.0.0/)
 and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0.html).
 
 ## [Unreleased]
+### Fixed
+- Fix attachment rendering ([#12](https://github.com/cucumber/cucumber-json-formatter/pull/7))
 
 ## [0.1.2] - 2025-09-03
 ### Fixed
-- `JvmArgument.val` and `JvmArgument.offset` are not required in practice  ([#7](https://github.com/cucumber/cucumber-json-formatter/pull/7) M.P. Korstanje)
+- `JvmArgument.val` and `JvmArgument.offset` are not required in practice  ([#7](https://github.com/cucumber/cucumber-json-formatter/pull/7))
 
 ## [0.1.1] - 2025-07-24
 ### Fixed
 - Change artifact name to `cucumber-json-formatter`
 
 ## [0.1.0] - 2025-07-24
 ### Added
-- Java implementation ([#1](https://github.com/cucumber/cucumber-json-formatter/pull/1) M.P. Korstanje)
+- Java implementation ([#1](https://github.com/cucumber/cucumber-json-formatter/pull/1))
 
 [Unreleased]: https://github.com/cucumber/cucumber-json-formatter/compare/v0.1.2...HEAD
 [0.1.2]: https://github.com/cucumber/cucumber-json-formatter/compare/v0.1.1...v0.1.2

java/src/main/java/io/cucumber/jsonformatter/JsonReportWriter.java

@@ -17,6 +17,7 @@
 import io.cucumber.jsonformatter.CucumberJvmJson.JvmTag;
 import io.cucumber.messages.Convertor;
 import io.cucumber.messages.types.Attachment;
+import io.cucumber.messages.types.AttachmentContentEncoding;
 import io.cucumber.messages.types.Background;
 import io.cucumber.messages.types.DataTable;
 import io.cucumber.messages.types.DocString;
@@ -55,6 +56,7 @@
 import java.time.ZoneOffset;
 import java.time.format.DateTimeFormatter;
 import java.util.ArrayList;
+import java.util.Base64;
 import java.util.Collection;
 import java.util.Collections;
 import java.util.HashMap;
@@ -70,8 +72,7 @@
 import java.util.stream.Stream;
 
 import static io.cucumber.jsonformatter.IdNamingVisitor.formatId;
-import static io.cucumber.messages.types.AttachmentContentEncoding.BASE64;
-import static io.cucumber.messages.types.AttachmentContentEncoding.IDENTITY;
+import static java.nio.charset.StandardCharsets.UTF_8;
 import static java.util.Collections.emptyList;
 import static java.util.Locale.ROOT;
 import static java.util.Objects.requireNonNull;
@@ -308,21 +309,59 @@ private JvmResult createJvmResult(TestStepResult result) {
 
     private List<JvmEmbedding> createEmbeddings(List<Attachment> attachments) {
         return attachments.stream()
-                .filter(attachment -> attachment.getContentEncoding() == BASE64)
+                .filter(attachment -> !isTextCucumberLogPlain(attachment.getMediaType()))
                 .map(attachment -> new JvmEmbedding(
                         attachment.getMediaType(),
-                        attachment.getBody(),
+                        // Scenario.attach creates both plain and base64 attachments
+                        encodeBodyAsBase64(attachment),
                         attachment.getFileName().orElse(null)))
                 .collect(toList());
     }
 
+    private static String encodeBodyAsBase64(Attachment attachment) {
+        AttachmentContentEncoding encoding = attachment.getContentEncoding();
+        String body = attachment.getBody();
+        switch (encoding) {
+            case IDENTITY:
+                byte[] bytes = body.getBytes(UTF_8);
+                Base64.Encoder encoder = Base64.getEncoder();
+                return encoder.encodeToString(bytes);
+            case BASE64:
+                return body;
+            default:
+                throw new RuntimeException("Unknown content encoding " + encoding);
+        }
+    }
+
     private List<String> createOutput(List<Attachment> attachments) {
         return attachments.stream()
-                .filter(attachment -> attachment.getContentEncoding() == IDENTITY)
-                .map(Attachment::getBody)
+                // Scenario.log creates text/x.cucumber.log+plain attachments
+                // These are written as plain text output elements in the json report                 
+                .filter(attachment -> isTextCucumberLogPlain(attachment.getMediaType()))
+                // If someone snuck in a text/x.cucumber.log+plain through Scenario.attach(byte[])
+                // we have to decode the body. 
+                .map(JsonReportWriter::encodeBodyAsPlainText)
                 .collect(toList());
     }
 
+    private static String encodeBodyAsPlainText(Attachment attachment) {
+        AttachmentContentEncoding encoding = attachment.getContentEncoding();
+        String body = attachment.getBody();
+        switch (encoding) {
+            case IDENTITY:
+                return body;
+            case BASE64:
+                Base64.Decoder decoder = Base64.getDecoder();
+                return new String(decoder.decode(body), UTF_8);
+            default:
+                throw new RuntimeException("Unknown content encoding " + encoding);
+        }
+    }
+
+    private static boolean isTextCucumberLogPlain(String mediaType) {
+        return mediaType.equals("text/x.cucumber.log+plain");
+    }
+
     private List<JvmLocationTag> createJvmLocationTags(Feature feature) {
         return feature.getTags().stream()
                 .map(this::createJvmLocationTag)

testdata/compatibility-kit/attachments.ndjson.jvm.json

@@ -37,8 +37,11 @@
               "duration": 1000000,
               "status": "passed"
             },
-            "output": [
-              "hello"
+            "embeddings": [
+              {
+                "mime_type": "application/octet-stream",
+                "data": "aGVsbG8="
+              }
             ]
           }
         ]
@@ -131,8 +134,11 @@
               "line": 25,
               "value": "{\"message\": \"The <b>big</b> question\", \"foo\": \"bar\"}"
             },
-            "output": [
-              "{\"message\": \"The <b>big</b> question\", \"foo\": \"bar\"}"
+            "embeddings": [
+              {
+                "mime_type": "application/json",
+                "data": "eyJtZXNzYWdlIjogIlRoZSA8Yj5iaWc8L2I+IHF1ZXN0aW9uIiwgImZvbyI6ICJiYXIifQ=="
+              }
             ]
           }
         ]
@@ -232,8 +238,11 @@
               "duration": 1000000,
               "status": "passed"
             },
-            "output": [
-              "https://cucumber.io"
+            "embeddings": [
+              {
+                "mime_type": "text/uri-list",
+                "data": "aHR0cHM6Ly9jdWN1bWJlci5pbw=="
+              }
             ]
           }
         ]