fix test

Signed-off-by: Stefan Niederhauser <[email protected]>

Author: nidi3

README.md

@@ -372,8 +372,16 @@ Processors can be registered to futher customize what goes in and out of the gra
 
 [//]: # (processor)
 ```java
-Graphviz g = Graphviz.fromGraph(graph().with(node("bad word").link("god word")))
-        .preProcessor((source, options, processOptions) -> source.replace("bad word", "unicorn"));
+Graph graph = graph().with(node("bad word").link("god word"));
+Graphviz g = Graphviz.fromGraph(graph)
+        .preProcessor((source, options, processOptions) -> source.replace("bad word", "unicorn"))
+        .postProcessor(((result, options, processOptions) ->
+                result.mapString(svg ->
+                        SvgElementFinder.use(svg, finder -> {
+                            finder.findNode("unicorn").setAttribute("class", "red");
+                        })
+                )
+        ));
 g.basedir(new File("example")).render(Format.PNG).toFile(new File("example/ex9.png"));
 ```
 [//]: # (end)

graphviz-java/example/ex9.png

@@ -39,6 +39,7 @@ public class SvgElementFinder {
     private static final XPathExpression EXPR_G = pathExpression(X_PATH, "//g");
     private static final XPathExpression EXPR_TITLE = pathExpression(X_PATH, "//title[text()=$var]");
     private static final XPathExpression EXPR_TITLE_OR = pathExpression(X_PATH, "//title[text()=$var or text()=$alt]");
+    private final boolean hasHeader;
     private final Document doc;
 
     public static String use(String svg, Consumer<SvgElementFinder> actions) {
@@ -50,6 +51,7 @@ public static String use(String svg, Consumer<SvgElementFinder> actions) {
     public SvgElementFinder(String svg) {
         try {
             doc = builder().parse(new InputSource(new StringReader(svg)));
+            hasHeader = svg.startsWith("<?xml");
         } catch (SAXException | IOException e) {
             throw new AssertionError("Could not read SVG", e);
         }
@@ -59,7 +61,8 @@ public String getSvg() {
         final StringWriter sw = new StringWriter();
         try {
             TRANSFORMER_FACTORY.newTransformer().transform(new DOMSource(doc), new StreamResult(sw));
-            return sw.toString();
+            final String out = sw.toString().replace("xmlns=\"\"", ""); //rasterizer don't like empty xmlns !?
+            return hasHeader ? out : out.substring(out.indexOf("?>") + 2);
         } catch (TransformerException e) {
             throw new AssertionError("Could not generate string from DOM", e);
         }

graphviz-java/src/main/java/guru/nidi/graphviz/model/SvgElementFinder.java

@@ -191,8 +191,16 @@ void ex8() throws IOException {
     @Test
     void ex9() throws IOException {
         //## processor
-        Graphviz g = Graphviz.fromGraph(graph().with(node("bad word").link("god word")))
-                .preProcessor((source, options, processOptions) -> source.replace("bad word", "unicorn"));
+        Graph graph = graph().with(node("bad word").link("good word"));
+        Graphviz g = Graphviz.fromGraph(graph)
+                .preProcessor((source, options, processOptions) -> source.replace("bad word", "unicorn"))
+                .postProcessor(((result, options, processOptions) ->
+                        result.mapString(svg ->
+                                SvgElementFinder.use(svg, finder -> {
+                                    finder.findNode("unicorn").setAttribute("class", "pink");
+                                })
+                        )
+                ));
         g.basedir(new File("example")).render(Format.PNG).toFile(new File("example/ex9.png"));
         //## image
     }

graphviz-java/src/test/java/guru/nidi/graphviz/model/ReadmeTest.java

@@ -17,7 +17,6 @@
 
 import guru.nidi.graphviz.attribute.Label;
 import guru.nidi.graphviz.engine.Graphviz;
-import guru.nidi.graphviz.model.*;
 import org.junit.jupiter.api.Test;
 
 import static guru.nidi.graphviz.engine.Format.SVG;