PropertiesFilesImporter.writeValueAsString does not escape special characters

Author: FrogDevelopper

consul-populate-core/src/main/java/com/frogdevelopment/consul/populate/files/PropertiesFilesImporter.java

@@ -2,6 +2,7 @@
 
 import java.io.File;
 import java.io.IOException;
+import java.io.StringWriter;
 import java.nio.file.Files;
 import java.nio.file.Path;
 import java.util.LinkedHashMap;
@@ -54,13 +55,18 @@ protected SequencedMap<String, Object> readFile(@NonNull final File file) throws
 
     @NonNull
     @Override
-    protected String writeValueAsString(@NonNull final Map<String, Object> map) {
-        if (map == null || map.isEmpty()) {
+    protected String writeValueAsString(@NonNull final Map<String, Object> map) throws IOException {
+        if (map.isEmpty()) {
             return "";
         }
-        return map.entrySet()
-                .stream()
-                .map(entry -> entry.getKey() + "=" + entry.getValue())
-                .collect(Collectors.joining("\n"));
+        final var properties = new Properties();
+        map.forEach((k, v) -> properties.setProperty(k, v.toString()));
+        final var sw = new StringWriter();
+        properties.store(sw, null);
+        // Properties.store() prepends a "#<timestamp>" comment line and a blank line — strip both
+        return sw.toString().lines()
+                .filter(line -> !line.startsWith("#"))
+                .collect(Collectors.joining("\n"))
+                .strip();
     }
 }

consul-populate-core/src/test/java/com/frogdevelopment/consul/populate/files/PropertiesFilesImporterTest.java

@@ -19,12 +19,12 @@ class PropertiesFilesImporterTest extends BaseFilesImporterTest {
     @Language("PROPERTIES")
     private static final String EXPECTED = """
             collection.items=item_C
-            very.deep.nested.field.that.will.but.not=here
-            very.deep.nested.field.that.will.be.overridden=salut
             foo.bar=new_value
             foo.baz=to_keep
             simple-value=kept
-            something.new=true""";
+            something.new=true
+            very.deep.nested.field.that.will.be.overridden=salut
+            very.deep.nested.field.that.will.but.not=here""";
 
     @Inject
     private PropertiesFilesImporter filesImporter;
@@ -56,8 +56,7 @@ void should_mergeProperties() {
     }
 
     @Test
-    void should_handle_empty() {
-        // given
+    void should_handle_empty() throws Exception {
         // when
         final var value = filesImporter.writeValueAsString(new TreeMap<>());