Avoid unnecessary parsing conditions

CHANGELOG.md

@@ -10,6 +10,9 @@ This document is formatted according to the principles of [Keep A CHANGELOG](htt
 ### Added
 - [Java] Add OSGi metadata ([#485](https://github.com/cucumber/gherkin/pull/485))
 
+### Fixed
+- [Java] Fixed `AstNode` conditions which never occur in `GherkinDocumentBuilder`.
+
 ## [36.0.0] - 2025-10-09
 ### Changed
 - [.NET, Elixir, Go, JavaScript, Java, Perl, Php, Ruby] Update dependency messages to v30

java/src/main/java/io/cucumber/gherkin/AstNode.java

@@ -38,6 +38,18 @@ <T> T getSingle(RuleType ruleType, T defaultResult) {
         return items == null ? defaultResult : items.get(0);
     }
 
+    @SuppressWarnings("unchecked")
+    <T> T getSingle(RuleType ruleType) {
+        // if not null, then at least one item is present because
+        // the list was created in add(), so no need to check isEmpty()
+        List<T> items = (List<T>) subItems.get(ruleType);
+        return items == null ? null : items.get(0);
+    }
+
+    <T> T getRequiredSingle(RuleType ruleType) {
+        return requireNonNull(getSingle(ruleType));
+    }
+
     @SuppressWarnings("unchecked")
     <T> List<T> getItems(RuleType ruleType) {
         List<T> items = (List<T>) subItems.get(ruleType);
@@ -48,7 +60,7 @@ <T> List<T> getItems(RuleType ruleType) {
     }
 
     Token getToken(TokenType tokenType) {
-        return requireNonNull(getSingle(tokenType.ruleType, null));
+        return getRequiredSingle(tokenType.ruleType);
     }
 
     List<Token> getTokens(TokenType tokenType) {

java/src/main/java/io/cucumber/gherkin/GherkinDocumentBuilder.java

@@ -83,8 +83,8 @@ private Object getTransformedNode(AstNode node) {
                         stepLine.matchedKeyword,
                         stepLine.keywordType,
                         stepLine.matchedText,
-                        node.getSingle(RuleType.DocString, null),
-                        node.getSingle(RuleType.DataTable, null),
+                        node.getSingle(RuleType.DocString),
+                        node.getSingle(RuleType.DataTable),
                         idGenerator.newId()
                 );
             }
@@ -116,7 +116,7 @@ private Object getTransformedNode(AstNode node) {
                 );
             }
             case ScenarioDefinition: {
-                AstNode scenarioNode = node.getSingle(RuleType.Scenario, null);
+                AstNode scenarioNode = node.getRequiredSingle(RuleType.Scenario);
                 Token scenarioLine = scenarioNode.getToken(TokenType.ScenarioLine);
 
                 return new Scenario(
@@ -131,11 +131,19 @@ private Object getTransformedNode(AstNode node) {
                 );
             }
             case ExamplesDefinition: {
-                AstNode examplesNode = node.getSingle(RuleType.Examples, null);
+                AstNode examplesNode = node.getRequiredSingle(RuleType.Examples);
                 Token examplesLine = examplesNode.getToken(TokenType.ExamplesLine);
-                List<TableRow> rows = examplesNode.getSingle(RuleType.ExamplesTable, null);
-                TableRow tableHeader = rows != null && !rows.isEmpty() ? rows.get(0) : null;
-                List<TableRow> tableBody = rows != null && !rows.isEmpty() ? rows.subList(1, rows.size()) : Collections.emptyList();
+                // rows is null when a Scenario Outline has no Examples table
+                List<TableRow> rows = examplesNode.getSingle(RuleType.ExamplesTable);
+                TableRow tableHeader;
+                List<TableRow> tableBody;
+                if (rows != null && !rows.isEmpty()) {
+                    tableHeader = rows.get(0);
+                    tableBody = rows.subList(1, rows.size());
+                } else {
+                    tableHeader = null;
+                    tableBody = Collections.emptyList();
+                }
 
                 return new Examples(
                         examplesLine.location,
@@ -146,7 +154,6 @@ private Object getTransformedNode(AstNode node) {
                         tableHeader,
                         tableBody,
                         idGenerator.newId()
-
                 );
             }
             case ExamplesTable: {
@@ -162,14 +169,13 @@ private Object getTransformedNode(AstNode node) {
                 return joinMatchedText(lineTokens, toIndex);
             }
             case Feature: {
-                AstNode header = node.getSingle(RuleType.FeatureHeader, new AstNode(RuleType.FeatureHeader));
-                if (header == null) return null;
+                AstNode header = node.getRequiredSingle(RuleType.FeatureHeader);
                 List<Tag> tags = getTags(header);
                 Token featureLine = header.getToken(TokenType.FeatureLine);
-                if (featureLine == null) return null;
 
                 List<FeatureChild> children = new ArrayList<>();
-                Background background = node.getSingle(RuleType.Background, null);
+                // Background is an optional element of a Feature, so can be null
+                Background background = node.getSingle(RuleType.Background);
                 if (background != null) {
                     children.add(new FeatureChild(null, background, null));
                 }
@@ -191,15 +197,14 @@ private Object getTransformedNode(AstNode node) {
                 );
             }
             case Rule: {
-                AstNode header = node.getSingle(RuleType.RuleHeader, new AstNode(RuleType.RuleHeader));
-                if (header == null) return null;
+                AstNode header = node.getRequiredSingle(RuleType.RuleHeader);
                 Token ruleLine = header.getToken(TokenType.RuleLine);
-                if (ruleLine == null) return null;
 
                 List<RuleChild> children = new ArrayList<>();
                 List<Tag> tags = getTags(header);
 
-                Background background = node.getSingle(RuleType.Background, null);
+                // Background is an optional element of a Feature, so can be null
+                Background background = node.getSingle(RuleType.Background);
                 if (background != null) {
                     children.add(new RuleChild(background, null));
                 }
@@ -220,7 +225,8 @@ private Object getTransformedNode(AstNode node) {
 
             }
             case GherkinDocument: {
-                Feature feature = node.getSingle(RuleType.Feature, null);
+                Feature feature = node.getSingle(RuleType.Feature);
+                // feature is null when the file is empty or contains only comments/whitespace, or no Cucumber feature
                 return new GherkinDocument(uri, feature, comments);
             }
 
@@ -293,9 +299,10 @@ private String getDescription(AstNode node) {
     }
 
     private List<Tag> getTags(AstNode node) {
-        AstNode tagsNode = node.getSingle(RuleType.Tags, null);
-        if (tagsNode == null)
+        AstNode tagsNode = node.getSingle(RuleType.Tags);
+        if (tagsNode == null) {// tags are optional
             return Collections.emptyList();
+        }
 
         List<Token> tokens = tagsNode.getTokens(TokenType.TagLine);
         List<Tag> tags = new ArrayList<>();
@@ -309,7 +316,7 @@ private List<Tag> getTags(AstNode node) {
 
     @Override
     public GherkinDocument getResult() {
-        return currentNode().getSingle(RuleType.GherkinDocument, null);
+        return currentNode().getSingle(RuleType.GherkinDocument);
     }
 
 }

java/src/test/java/io/cucumber/gherkin/AstNodeTest.java

@@ -43,4 +43,26 @@ void getSingle_returns_first_item() {
         // Then
         assertEquals(item1, astNode.getSingle(Parser.RuleType.Step, "defaultValue"));
     }
+
+    @Test
+    void getRequiredSingle_throws_exception_when_no_items() {
+        // Given a node
+        AstNode astNode = new AstNode(Parser.RuleType.Step);
+
+        // When no subItem is present
+
+        // Then
+        assertThrows(NullPointerException.class, () -> astNode.getRequiredSingle(Parser.RuleType.Scenario));
+    }
+
+    @Test
+    void getSingle_return_null_when_no_items() {
+        // Given a node
+        AstNode astNode = new AstNode(Parser.RuleType.Step);
+
+        // When no subItem is present
+
+        // Then
+        assertNull(astNode.getSingle(Parser.RuleType.Scenario));
+    }
 }

java/src/test/java/io/cucumber/gherkin/GherkinDocumentBuilderTest.java

@@ -87,7 +87,9 @@ void sets_empty_table_cells() {
                 "      |a||b|",
                 "test.feature"
         );
-        TableRow row = doc.getFeature().get().getChildren().get(0).getScenario().get().getSteps().get(0).getDataTable().get().getRows().get(0);
+        List<FeatureChild> children = doc.getFeature().get().getChildren();
+        assertEquals(1, children.size());
+        TableRow row = children.get(0).getScenario().get().getSteps().get(0).getDataTable().get().getRows().get(0);
         assertEquals("a", row.getCells().get(0).getValue());
         assertEquals("", row.getCells().get(1).getValue());
         assertEquals("b", row.getCells().get(2).getValue());

java/src/test/java/io/cucumber/gherkin/TestDataTest.java

@@ -0,0 +1,32 @@
+package io.cucumber.gherkin;
+
+import org.junit.jupiter.api.Test;
+
+import java.io.IOException;
+import java.nio.file.Files;
+import java.nio.file.Path;
+import java.nio.file.Paths;
+import java.util.stream.Stream;
+
+public class TestDataTest {
+    @Test
+    void testdata_features_are_parsed_without_NPE() throws IOException {
+        GherkinParser gherkinParser = GherkinParser.builder()
+                .idGenerator(new IncrementingIdGenerator())
+                .build();
+        try (Stream<Path> list = Stream.of(
+                Files.list(Paths.get("../testdata/good/")),
+                Files.list(Paths.get("../testdata/bad/")))
+                .flatMap(s -> s)) {
+            list
+            .filter(path -> path.toString().endsWith(".feature"))
+            .forEach(source -> {
+                try {
+                    gherkinParser.parse(source);
+                } catch (IOException e) {
+                    throw new RuntimeException(e);
+                }
+            });
+        }
+    }
+}