Add ConfigRenderOptions and ConfigValue#render(options)

This mostly lets you choose whether you want whitespace and
comments, and somewhat as a side effect, you can get plain
JSON by turning off comments.

config/src/main/java/com/typesafe/config/ConfigRenderOptions.java

@@ -0,0 +1,134 @@
+/**
+ *   Copyright (C) 2011-2012 Typesafe Inc. <http://typesafe.com>
+ */
+package com.typesafe.config;
+
+/**
+ * <p>
+ * A set of options related to rendering a {@link ConfigValue}. Passed to
+ * {@link ConfigValue#render(ConfigRenderOptions)}.
+ *
+ * <p>
+ * Here is an example of creating a {@code ConfigRenderOptions}:
+ *
+ * <pre>
+ *     ConfigRenderOptions options =
+ *         ConfigRenderOptions.defaults().setComments(false)
+ * </pre>
+ */
+public final class ConfigRenderOptions {
+    private final boolean originComments;
+    private final boolean comments;
+    private final boolean formatted;
+
+    private ConfigRenderOptions(boolean originComments, boolean comments, boolean formatted) {
+        this.originComments = originComments;
+        this.comments = comments;
+        this.formatted = formatted;
+    }
+
+    /**
+     * Returns the default render options which are verbose (commented and
+     * formatted). See {@link ConfigRenderOptions#concise} for stripped-down
+     * options. This rendering will not be valid JSON since it has comments.
+     *
+     * @return the default render options
+     */
+    public static ConfigRenderOptions defaults() {
+        return new ConfigRenderOptions(true, true, true);
+    }
+
+    /**
+     * Returns concise render options (no whitespace or comments). For a
+     * resolved {@link Config}, the concise rendering will be valid JSON.
+     *
+     * @return the concise render options
+     */
+    public static ConfigRenderOptions concise() {
+        return new ConfigRenderOptions(false, false, false);
+    }
+
+    /**
+     * Returns options with comments toggled. This controls human-written
+     * comments but not the autogenerated "origin of this setting" comments,
+     * which are controlled by {@link ConfigRenderOptions#setOriginComments}.
+     *
+     * @param value
+     *            true to include comments in the render
+     * @return options with requested setting for comments
+     */
+    public ConfigRenderOptions setComments(boolean value) {
+        if (value == comments)
+            return this;
+        else
+            return new ConfigRenderOptions(originComments, value, formatted);
+    }
+
+    /**
+     * Returns whether the options enable comments. This method is mostly used
+     * by the config lib internally, not by applications.
+     *
+     * @return true if comments should be rendered
+     */
+    public boolean getComments() {
+        return comments;
+    }
+
+    /**
+     * Returns options with origin comments toggled. If this is enabled, the
+     * library generates comments for each setting based on the
+     * {@link ConfigValue#origin} of that setting's value. For example these
+     * comments might tell you which file a setting comes from.
+     * 
+     * <p>
+     * {@code setOriginComments()} controls only these autogenerated
+     * "origin of this setting" comments, to toggle regular comments use
+     * {@link ConfigRenderOptions#setComments}.
+     *
+     * @param value
+     *            true to include autogenerated setting-origin comments in the
+     *            render
+     * @return options with origin comments toggled
+     */
+    public ConfigRenderOptions setOriginComments(boolean value) {
+        if (value == originComments)
+            return this;
+        else
+            return new ConfigRenderOptions(value, comments, formatted);
+    }
+
+    /**
+     * Returns whether the options enable automated origin comments. This method
+     * is mostly used by the config lib internally, not by applications.
+     *
+     * @return true if origin comments should be rendered
+     */
+    public boolean getOriginComments() {
+        return originComments;
+    }
+
+    /**
+     * Returns options with formatting toggled. Formatting means indentation and
+     * whitespace, enabling formatting makes things prettier but larger.
+     *
+     * @param value
+     *            true to include comments in the render
+     * @return options with requested setting for formatting
+     */
+    public ConfigRenderOptions setFormatted(boolean value) {
+        if (value == formatted)
+            return this;
+        else
+            return new ConfigRenderOptions(originComments, comments, value);
+    }
+
+    /**
+     * Returns whether the options enable formatting. This method is mostly used
+     * by the config lib internally, not by applications.
+     *
+     * @return true if comments should be rendered
+     */
+    public boolean getFormatted() {
+        return formatted;
+    }
+}

config/src/main/java/com/typesafe/config/ConfigValue.java

@@ -46,15 +46,43 @@ public interface ConfigValue extends ConfigMergeable {
     /**
      * Renders the config value as a HOCON string. This method is primarily
      * intended for debugging, so it tries to add helpful comments and
-     * whitespace. If the config value has not been resolved (see
-     * {@link Config#resolve}), it's possible that it can't be rendered as valid
-     * HOCON. In that case the rendering should still be useful for debugging
-     * but you might not be able to parse it.
-     * 
+     * whitespace.
+     *
+     * <p>
+     * If the config value has not been resolved (see {@link Config#resolve}),
+     * it's possible that it can't be rendered as valid HOCON. In that case the
+     * rendering should still be useful for debugging but you might not be able
+     * to parse it.
+     *
+     * <p>
+     * This method is equivalent to
+     * {@code render(ConfigRenderOptions.defaults())}.
+     *
      * @return the rendered value
      */
     String render();
 
+    /**
+     * Renders the config value to a string, using the provided options.
+     *
+     * <p>
+     * If the config value has not been resolved (see {@link Config#resolve}),
+     * it's possible that it can't be rendered as valid HOCON. In that case the
+     * rendering should still be useful for debugging but you might not be able
+     * to parse it.
+     *
+     * <p>
+     * If the config value has been resolved and the options disable all
+     * HOCON-specific features (such as comments), the rendering will be valid
+     * JSON. If you enable HOCON-only features such as comments, the rendering
+     * will not be valid JSON.
+     * 
+     * @param options
+     *            the rendering options
+     * @return the rendered value
+     */
+    String render(ConfigRenderOptions options);
+
     @Override
     ConfigValue withFallback(ConfigMergeable other);
 }

config/src/main/java/com/typesafe/config/impl/AbstractConfigObject.java

@@ -13,6 +13,7 @@ import com.typesafe.config.ConfigException;
 import com.typesafe.config.ConfigMergeable;
 import com.typesafe.config.ConfigObject;
 import com.typesafe.config.ConfigOrigin;
+import com.typesafe.config.ConfigRenderOptions;
 import com.typesafe.config.ConfigValue;
 import com.typesafe.config.ConfigValueType;
 
@@ -212,7 +213,7 @@ abstract class AbstractConfigObject extends AbstractConfigValue implements Confi
     public abstract AbstractConfigValue get(Object key);
 
     @Override
-    protected abstract void render(StringBuilder sb, int indent, boolean formatted);
+    protected abstract void render(StringBuilder sb, int indent, ConfigRenderOptions options);
 
     private static UnsupportedOperationException weAreImmutable(String method) {
         return new UnsupportedOperationException("ConfigObject is immutable, you can't call Map."

config/src/main/java/com/typesafe/config/impl/AbstractConfigValue.java

@@ -11,6 +11,7 @@ import java.util.List;
 import com.typesafe.config.ConfigException;
 import com.typesafe.config.ConfigMergeable;
 import com.typesafe.config.ConfigOrigin;
+import com.typesafe.config.ConfigRenderOptions;
 import com.typesafe.config.ConfigValue;
 
 /**
@@ -276,36 +277,45 @@ abstract class AbstractConfigValue implements ConfigValue, MergeableValue {
     @Override
     public final String toString() {
         StringBuilder sb = new StringBuilder();
-        render(sb, 0, null /* atKey */, false /* formatted */);
+        render(sb, 0, null /* atKey */, ConfigRenderOptions.concise());
         return getClass().getSimpleName() + "(" + sb.toString() + ")";
     }
 
-    protected static void indent(StringBuilder sb, int indent) {
-        int remaining = indent;
-        while (remaining > 0) {
-            sb.append("    ");
-            --remaining;
+    protected static void indent(StringBuilder sb, int indent, ConfigRenderOptions options) {
+        if (options.getFormatted()) {
+            int remaining = indent;
+            while (remaining > 0) {
+                sb.append("    ");
+                --remaining;
+            }
         }
     }
 
-    protected void render(StringBuilder sb, int indent, String atKey, boolean formatted) {
+    protected void render(StringBuilder sb, int indent, String atKey, ConfigRenderOptions options) {
         if (atKey != null) {
             sb.append(ConfigImplUtil.renderJsonString(atKey));
-            sb.append(" : ");
+            if (options.getFormatted())
+                sb.append(" : ");
+            else
+                sb.append(":");
         }
-        render(sb, indent, formatted);
+        render(sb, indent, options);
     }
 
-    protected void render(StringBuilder sb, int indent, boolean formatted) {
+    protected void render(StringBuilder sb, int indent, ConfigRenderOptions options) {
         Object u = unwrapped();
         sb.append(u.toString());
     }
 
-
     @Override
     public final String render() {
+        return render(ConfigRenderOptions.defaults());
+    }
+
+    @Override
+    public final String render(ConfigRenderOptions options) {
         StringBuilder sb = new StringBuilder();
-        render(sb, 0, null, true /* formatted */);
+        render(sb, 0, null, options);
         return sb.toString();
     }
 

config/src/main/java/com/typesafe/config/impl/ConfigConcatenation.java

@@ -8,6 +8,7 @@ import java.util.List;
 import com.typesafe.config.ConfigException;
 import com.typesafe.config.ConfigObject;
 import com.typesafe.config.ConfigOrigin;
+import com.typesafe.config.ConfigRenderOptions;
 import com.typesafe.config.ConfigValueType;
 
 /**
@@ -222,9 +223,9 @@ final class ConfigConcatenation extends AbstractConfigValue implements Unmergeab
     }
 
     @Override
-    protected void render(StringBuilder sb, int indent, boolean formatted) {
+    protected void render(StringBuilder sb, int indent, ConfigRenderOptions options) {
         for (AbstractConfigValue p : pieces) {
-            p.render(sb, indent, formatted);
+            p.render(sb, indent, options);
         }
     }
 

config/src/main/java/com/typesafe/config/impl/ConfigDelayedMerge.java

@@ -10,6 +10,7 @@ import java.util.List;
 
 import com.typesafe.config.ConfigException;
 import com.typesafe.config.ConfigOrigin;
+import com.typesafe.config.ConfigRenderOptions;
 import com.typesafe.config.ConfigValueType;
 
 /**
@@ -215,18 +216,20 @@ final class ConfigDelayedMerge extends AbstractConfigValue implements Unmergeabl
     }
 
     @Override
-    protected void render(StringBuilder sb, int indent, String atKey, boolean formatted) {
-        render(stack, sb, indent, atKey, formatted);
+    protected void render(StringBuilder sb, int indent, String atKey, ConfigRenderOptions options) {
+        render(stack, sb, indent, atKey, options);
     }
 
     // static method also used by ConfigDelayedMergeObject.
     static void render(List<AbstractConfigValue> stack, StringBuilder sb, int indent, String atKey,
-            boolean formatted) {
-        if (formatted) {
+            ConfigRenderOptions options) {
+        boolean commentMerge = options.getComments();
+        if (commentMerge) {
             sb.append("# unresolved merge of " + stack.size() + " values follows (\n");
             if (atKey == null) {
-                indent(sb, indent);
+                indent(sb, indent, options);
                 sb.append("# this unresolved merge will not be parseable because it's at the root of the object\n");
+                indent(sb, indent, options);
                 sb.append("# the HOCON format has no way to list multiple root objects in a single file\n");
             }
         }
@@ -237,8 +240,8 @@ final class ConfigDelayedMerge extends AbstractConfigValue implements Unmergeabl
 
         int i = 0;
         for (AbstractConfigValue v : reversed) {
-            if (formatted) {
-                indent(sb, indent);
+            if (commentMerge) {
+                indent(sb, indent, options);
                 if (atKey != null) {
                     sb.append("#     unmerged value " + i + " for key "
                             + ConfigImplUtil.renderJsonString(atKey) + " from ");
@@ -248,30 +251,36 @@ final class ConfigDelayedMerge extends AbstractConfigValue implements Unmergeabl
                 i += 1;
                 sb.append(v.origin().description());
                 sb.append("\n");
+
                 for (String comment : v.origin().comments()) {
-                    indent(sb, indent);
+                    indent(sb, indent, options);
                     sb.append("# ");
                     sb.append(comment);
                     sb.append("\n");
                 }
-                indent(sb, indent);
             }
+            indent(sb, indent, options);
 
             if (atKey != null) {
                 sb.append(ConfigImplUtil.renderJsonString(atKey));
-                sb.append(" : ");
+                if (options.getFormatted())
+                    sb.append(" : ");
+                else
+                    sb.append(":");
             }
-            v.render(sb, indent, formatted);
+            v.render(sb, indent, options);
             sb.append(",");
-            if (formatted)
+            if (options.getFormatted())
                 sb.append('\n');
         }
         // chop comma or newline
         sb.setLength(sb.length() - 1);
-        if (formatted) {
+        if (options.getFormatted()) {
             sb.setLength(sb.length() - 1); // also chop comma
             sb.append("\n"); // put a newline back
-            indent(sb, indent);
+        }
+        if (commentMerge) {
+            indent(sb, indent, options);
             sb.append("# ) end of unresolved merge\n");
         }
     }

config/src/main/java/com/typesafe/config/impl/ConfigDelayedMergeObject.java

@@ -13,6 +13,7 @@ import com.typesafe.config.ConfigException;
 import com.typesafe.config.ConfigList;
 import com.typesafe.config.ConfigMergeable;
 import com.typesafe.config.ConfigOrigin;
+import com.typesafe.config.ConfigRenderOptions;
 import com.typesafe.config.ConfigValue;
 
 // This is just like ConfigDelayedMerge except we know statically
@@ -168,13 +169,13 @@ final class ConfigDelayedMergeObject extends AbstractConfigObject implements Unm
     }
 
     @Override
-    protected void render(StringBuilder sb, int indent, String atKey, boolean formatted) {
-        ConfigDelayedMerge.render(stack, sb, indent, atKey, formatted);
+    protected void render(StringBuilder sb, int indent, String atKey, ConfigRenderOptions options) {
+        ConfigDelayedMerge.render(stack, sb, indent, atKey, options);
     }
 
     @Override
-    protected void render(StringBuilder sb, int indent, boolean formatted) {
-        render(sb, indent, null, formatted);
+    protected void render(StringBuilder sb, int indent, ConfigRenderOptions options) {
+        render(sb, indent, null, options);
     }
 
     private static ConfigException notResolved() {

config/src/main/java/com/typesafe/config/impl/ConfigNull.java

@@ -7,6 +7,7 @@ import java.io.ObjectStreamException;
 import java.io.Serializable;
 
 import com.typesafe.config.ConfigOrigin;
+import com.typesafe.config.ConfigRenderOptions;
 import com.typesafe.config.ConfigValueType;
 
 /**
@@ -41,7 +42,7 @@ final class ConfigNull extends AbstractConfigValue implements Serializable {
     }
 
     @Override
-    protected void render(StringBuilder sb, int indent, boolean formatted) {
+    protected void render(StringBuilder sb, int indent, ConfigRenderOptions options) {
         sb.append("null");
     }
 

config/src/main/java/com/typesafe/config/impl/ConfigReference.java

@@ -5,6 +5,7 @@ import java.util.Collections;
 
 import com.typesafe.config.ConfigException;
 import com.typesafe.config.ConfigOrigin;
+import com.typesafe.config.ConfigRenderOptions;
 import com.typesafe.config.ConfigValueType;
 
 /**
@@ -126,7 +127,7 @@ final class ConfigReference extends AbstractConfigValue implements Unmergeable {
     }
 
     @Override
-    protected void render(StringBuilder sb, int indent, boolean formatted) {
+    protected void render(StringBuilder sb, int indent, ConfigRenderOptions options) {
         sb.append(expr.toString());
     }
 

config/src/main/java/com/typesafe/config/impl/ConfigString.java

@@ -7,6 +7,7 @@ import java.io.ObjectStreamException;
 import java.io.Serializable;
 
 import com.typesafe.config.ConfigOrigin;
+import com.typesafe.config.ConfigRenderOptions;
 import com.typesafe.config.ConfigValueType;
 
 final class ConfigString extends AbstractConfigValue implements Serializable {
@@ -36,7 +37,7 @@ final class ConfigString extends AbstractConfigValue implements Serializable {
     }
 
     @Override
-    protected void render(StringBuilder sb, int indent, boolean formatted) {
+    protected void render(StringBuilder sb, int indent, ConfigRenderOptions options) {
         sb.append(ConfigImplUtil.renderJsonString(value));
     }
 

config/src/main/java/com/typesafe/config/impl/SimpleConfigList.java

@@ -14,6 +14,7 @@ import java.util.ListIterator;
 import com.typesafe.config.ConfigException;
 import com.typesafe.config.ConfigList;
 import com.typesafe.config.ConfigOrigin;
+import com.typesafe.config.ConfigRenderOptions;
 import com.typesafe.config.ConfigValue;
 import com.typesafe.config.ConfigValueType;
 
@@ -166,39 +167,40 @@ final class SimpleConfigList extends AbstractConfigValue implements ConfigList,
     }
 
     @Override
-    protected void render(StringBuilder sb, int indent, boolean formatted) {
+    protected void render(StringBuilder sb, int indent, ConfigRenderOptions options) {
         if (value.isEmpty()) {
             sb.append("[]");
         } else {
             sb.append("[");
-            if (formatted)
+            if (options.getFormatted())
                 sb.append('\n');
             for (AbstractConfigValue v : value) {
-                if (formatted) {
-                    indent(sb, indent + 1);
+                if (options.getOriginComments()) {
+                    indent(sb, indent + 1, options);
                     sb.append("# ");
                     sb.append(v.origin().description());
                     sb.append("\n");
-
+                }
+                if (options.getComments()) {
                     for (String comment : v.origin().comments()) {
-                        indent(sb, indent + 1);
+                        indent(sb, indent + 1, options);
                         sb.append("# ");
                         sb.append(comment);
                         sb.append("\n");
                     }
-
-                    indent(sb, indent + 1);
                 }
-                v.render(sb, indent + 1, formatted);
+                indent(sb, indent + 1, options);
+
+                v.render(sb, indent + 1, options);
                 sb.append(",");
-                if (formatted)
+                if (options.getFormatted())
                     sb.append('\n');
             }
             sb.setLength(sb.length() - 1); // chop or newline
-            if (formatted) {
+            if (options.getFormatted()) {
                 sb.setLength(sb.length() - 1); // also chop comma
                 sb.append('\n');
-                indent(sb, indent);
+                indent(sb, indent, options);
             }
             sb.append("]");
         }

config/src/main/java/com/typesafe/config/impl/SimpleConfigObject.java

@@ -18,6 +18,7 @@ import java.util.Set;
 import com.typesafe.config.ConfigException;
 import com.typesafe.config.ConfigObject;
 import com.typesafe.config.ConfigOrigin;
+import com.typesafe.config.ConfigRenderOptions;
 import com.typesafe.config.ConfigValue;
 
 final class SimpleConfigObject extends AbstractConfigObject implements Serializable {
@@ -324,41 +325,43 @@ final class SimpleConfigObject extends AbstractConfigObject implements Serializa
     }
 
     @Override
-    protected void render(StringBuilder sb, int indent, boolean formatted) {
+    protected void render(StringBuilder sb, int indent, ConfigRenderOptions options) {
         if (isEmpty()) {
             sb.append("{}");
         } else {
             sb.append("{");
-            if (formatted)
+            if (options.getFormatted())
                 sb.append('\n');
             for (String k : keySet()) {
                 AbstractConfigValue v;
                 v = value.get(k);
 
-                if (formatted) {
-                    indent(sb, indent + 1);
+                if (options.getOriginComments()) {
+                    indent(sb, indent + 1, options);
                     sb.append("# ");
                     sb.append(v.origin().description());
                     sb.append("\n");
+                }
+                if (options.getComments()) {
                     for (String comment : v.origin().comments()) {
-                        indent(sb, indent + 1);
+                        indent(sb, indent + 1, options);
                         sb.append("# ");
                         sb.append(comment);
                         sb.append("\n");
                     }
-                    indent(sb, indent + 1);
                 }
-                v.render(sb, indent + 1, k, formatted);
+                indent(sb, indent + 1, options);
+                v.render(sb, indent + 1, k, options);
                 sb.append(",");
-                if (formatted)
+                if (options.getFormatted())
                     sb.append('\n');
             }
             // chop comma or newline
             sb.setLength(sb.length() - 1);
-            if (formatted) {
+            if (options.getFormatted()) {
                 sb.setLength(sb.length() - 1); // also chop comma
                 sb.append("\n"); // put a newline back
-                indent(sb, indent);
+                indent(sb, indent, options);
             }
             sb.append("}");
         }

config/src/test/scala/Rendering.scala

@@ -1,17 +1,26 @@
 import com.typesafe.config.ConfigFactory
+import com.typesafe.config.ConfigRenderOptions
 
 object RenderExample extends App {
+    val formatted = args.contains("--formatted")
+    val originComments = args.contains("--origin-comments")
+    val comments = args.contains("--comments")
+    val options = ConfigRenderOptions.defaults()
+        .setFormatted(formatted)
+        .setOriginComments(originComments)
+        .setComments(comments)
+
     def render(what: String) {
         val conf = ConfigFactory.defaultOverrides()
             .withFallback(ConfigFactory.parseResourcesAnySyntax(classOf[ConfigFactory], "/" + what))
             .withFallback(ConfigFactory.defaultReference())
 
         println("=== BEGIN UNRESOLVED " + what)
-        println(conf.root.render())
+        println(conf.root.render(options))
         println("=== END UNRESOLVED " + what)
 
         println("=== BEGIN RESOLVED " + what)
-        println(conf.resolve().root.render())
+        println(conf.resolve().root.render(options))
         println("=== END RESOLVED " + what)
 
         println("=== BEGIN UNRESOLVED toString() " + what)

config/src/test/scala/com/typesafe/config/impl/ConcatenationTest.scala

@@ -51,7 +51,7 @@ class ConcatenationTest extends TestUtils {
         assertTrue("wrong exception: " + e.getMessage,
             e.getMessage.contains("Cannot concatenate") &&
                 e.getMessage.contains("abc") &&
-                e.getMessage.contains("""{"x" : "y"}"""))
+                e.getMessage.contains("""{"x":"y"}"""))
     }
 
     @Test
@@ -62,7 +62,7 @@ class ConcatenationTest extends TestUtils {
         assertTrue("wrong exception: " + e.getMessage,
             e.getMessage.contains("Cannot concatenate") &&
                 e.getMessage.contains("null") &&
-                e.getMessage.contains("""{"x" : "y"}"""))
+                e.getMessage.contains("""{"x":"y"}"""))
     }
 
     @Test
@@ -293,7 +293,7 @@ class ConcatenationTest extends TestUtils {
         }
         assertTrue("wrong exception: " + e.getMessage,
             e.getMessage.contains("Cannot concatenate") &&
-                e.getMessage.contains("\"x\" : \"y\"") &&
+                e.getMessage.contains("\"x\":\"y\"") &&
                 e.getMessage.contains("[2]"))
     }
 

config/src/test/scala/com/typesafe/config/impl/ConfigTest.scala

@@ -16,6 +16,8 @@ import java.io.File
 import com.typesafe.config.ConfigParseOptions
 import com.typesafe.config.ConfigFactory
 import com.typesafe.config.ConfigMergeable
+import com.typesafe.config.ConfigRenderOptions
+import com.typesafe.config.ConfigSyntax
 
 class ConfigTest extends TestUtils {
 
@@ -989,22 +991,46 @@ class ConfigTest extends TestUtils {
 
     @Test
     def renderRoundTrip() {
+        val allBooleans = true :: false :: Nil
+        val optionsCombos = {
+            for (
+                formatted <- allBooleans;
+                originComments <- allBooleans;
+                comments <- allBooleans
+            ) yield ConfigRenderOptions.defaults()
+                .setFormatted(formatted)
+                .setOriginComments(originComments)
+                .setComments(comments)
+        } toSeq
+
         for (i <- 1 to 10) {
             val numString = i.toString
             val name = "/test" + { if (numString.size == 1) "0" else "" } + numString
             val conf = ConfigFactory.parseResourcesAnySyntax(classOf[ConfigTest], name,
                 ConfigParseOptions.defaults().setAllowMissing(false))
-            val unresolvedRender = conf.root.render()
-            val resolved = conf.resolve()
-            val resolvedRender = resolved.root.render()
-            try {
-                assertEquals(conf.root, ConfigFactory.parseString(unresolvedRender, ConfigParseOptions.defaults()).root)
-                assertEquals(resolved.root, ConfigFactory.parseString(resolvedRender, ConfigParseOptions.defaults()).root)
-            } catch {
-                case e: Throwable =>
-                    System.err.println("unresolvedRender = " + unresolvedRender)
-                    System.err.println("resolvedRender = " + resolvedRender)
-                    throw e
+            for (renderOptions <- optionsCombos) {
+                val unresolvedRender = conf.root.render(renderOptions)
+                val resolved = conf.resolve()
+                val resolvedRender = resolved.root.render(renderOptions)
+                try {
+                    assertEquals(conf.root, ConfigFactory.parseString(unresolvedRender, ConfigParseOptions.defaults()).root)
+                    assertEquals(resolved.root, ConfigFactory.parseString(resolvedRender, ConfigParseOptions.defaults()).root)
+                } catch {
+                    case e: Exception =>
+                        System.err.println("unresolvedRender = " + unresolvedRender)
+                        System.err.println("resolvedRender = " + resolvedRender)
+                        throw e
+                }
+                if (!(renderOptions.getComments() || renderOptions.getOriginComments())) {
+                    // should get valid JSON if we don't have comments and are resolved
+                    val json = try {
+                        ConfigFactory.parseString(resolvedRender, ConfigParseOptions.defaults().setSyntax(ConfigSyntax.JSON));
+                    } catch {
+                        case e: Exception =>
+                            System.err.println("resolvedRender is not valid json: " + resolvedRender)
+                            throw e
+                    }
+                }
             }
         }
     }