Handles special case of an unquoted string containing an unresolved v…

…ariable reference next to some text. The rendering call from the parser will wrap the string in double quotes if it contains special characters. Since we resolve references at a later time in Helidon config, we need to drop the quotes to avoid altering the config value. See issue 9254.

config/hocon/pom.xml

@@ -74,6 +74,7 @@
                 <artifactId>maven-surefire-plugin</artifactId>
                 <configuration>
                     <environmentVariables>
+                        <VAR1>foo</VAR1>
                         <HOCON_TEST_PROPERTY>This Is My ENV VARS Value.</HOCON_TEST_PROPERTY>
                     </environmentVariables>
                 </configuration>

config/hocon/src/main/java/io/helidon/config/hocon/HoconConfigParser.java

@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2020, 2022 Oracle and/or its affiliates.
+ * Copyright (c) 2020, 2024 Oracle and/or its affiliates.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -37,7 +37,9 @@
 import com.typesafe.config.ConfigList;
 import com.typesafe.config.ConfigObject;
 import com.typesafe.config.ConfigParseOptions;
+import com.typesafe.config.ConfigRenderOptions;
 import com.typesafe.config.ConfigResolveOptions;
+import com.typesafe.config.ConfigValue;
 
 /**
  * Typesafe (Lightbend) Config (HOCON) {@link ConfigParser} implementation that supports following media types:
@@ -70,10 +72,13 @@ public class HoconConfigParser implements ConfigParser {
      * Priority of the parser used if registered by {@link io.helidon.config.Config.Builder} automatically.
      */
     public static final int PRIORITY = ConfigParser.PRIORITY + 100;
+
     private static final List<String> SUPPORTED_SUFFIXES = List.of("json", "conf");
+    private static final ConfigRenderOptions CONFIG_RENDER_OPTIONS = ConfigRenderOptions.defaults().setJson(false);
     private static final Set<String> SUPPORTED_MEDIA_TYPES =
             Set.of(MEDIA_TYPE_APPLICATION_HOCON, MEDIA_TYPE_APPLICATION_JSON);
 
+
     private final boolean resolvingEnabled;
     private final ConfigResolveOptions resolveOptions;
     private final ConfigParseOptions parseOptions;
@@ -176,7 +181,7 @@ private static ObjectNode fromConfig(ConfigObject config) {
                     // An unresolved ConfigReference resolved later in config module since
                     // Helidon and Hocon use the same reference syntax and resolving here
                     // would be too early for resolution across sources
-                    builder.addValue(key, value.render());
+                    builder.addValue(key, renderUnresolvedValue(value));
                 }
             }
         });
@@ -202,11 +207,32 @@ private static ListNode fromList(ConfigList list) {
                     // An unresolved ConfigReference resolved later in config module since
                     // Helidon and Hocon use the same reference syntax and resolving here
                     // would be too early for resolution across sources
-                    builder.addValue(value.render());
+                    builder.addValue(renderUnresolvedValue(value));
                 }
             }
         });
         return builder.build();
     }
 
+    /**
+     * <p>Special rendering for a non-structured, unquoted string value that includes
+     * one or more unresolved variable references such as {@code ${var}}. If an unresolved variable
+     * is either preceded and/or followed by a string containing non-alphabetic characters,
+     * it will be rendered in double quotes. For example, {@code ${var}/foo} will be
+     * rendered as {@code ${var}"/foo"} instead of {@code ${var}/foo}.
+     *
+     * <p>Note that if the original string was already in double quotes (not unquoted in
+     * HOCON terms) it will never throw {@link com.typesafe.config.ConfigException.NotResolved}
+     * since variable references in quotes are never resolved. This method will never be
+     * called as a result.
+     *
+     * @param unresolved string containing one or more unresolved references, typically a
+     *                   concatenation node with a combination of strings and unresolved
+     *                   references.
+     * @return a rendering, possibly with double quotes removed
+     */
+    private static String renderUnresolvedValue(ConfigValue unresolved) {
+        String rendering = unresolved.render(CONFIG_RENDER_OPTIONS);
+        return rendering.contains("\"") ? rendering.replace("\"", "") : rendering;
+    }
 }

config/hocon/src/test/java/io/helidon/config/hocon/SubstitutionTest.java

@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2022 Oracle and/or its affiliates.
+ * Copyright (c) 2022, 2024 Oracle and/or its affiliates.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -19,9 +19,12 @@
 import java.util.Collection;
 import java.util.Collections;
 import java.util.List;
+import java.util.NoSuchElementException;
 
 import io.helidon.config.ClasspathConfigSource;
 import io.helidon.config.Config;
+import io.helidon.config.ConfigSources;
+
 import org.hamcrest.Matchers;
 import org.junit.jupiter.api.Test;
 
@@ -55,4 +58,18 @@ void testSubstitution() {
         assertThat(list, Matchers.<Collection<String>> allOf(
                 hasSize(2), hasItem(is("Hello"))));
     }
+
+    @Test
+    void testHoconExpansion() {
+        Config config = Config.create(
+                ConfigSources.create("foo: ${VAR1}/bar", "application/hocon"));
+        assertThat(config.get("foo").asString().orElseThrow(NoSuchElementException::new), is("foo/bar"));
+    }
+
+    @Test
+    void testHoconExpansionQuotes() {
+        Config config = Config.create(
+                ConfigSources.create("foo: \"${VAR1}/bar\"", "application/hocon"));
+        assertThat(config.get("foo").asString().orElseThrow(NoSuchElementException::new), is("foo/bar"));
+    }
 }