Fix #50

Author: cowtowncoder

csv/pom.xml

@@ -40,7 +40,7 @@ abstractions.
     <dependency>
       <groupId>com.google.guava</groupId>
       <artifactId>guava</artifactId>
-      <version>16.0.1</version>
+      <version>18.0</version>
       <scope>test</scope>
     </dependency>
   </dependencies>

properties/pom.xml

@@ -27,11 +27,7 @@ configuration files as if there was implied nesting structure (by default using
       <scope>provided</scope>
     </dependency>
 
-    <dependency>
-      <groupId>com.fasterxml.jackson.core</groupId>
-      <artifactId>jackson-annotations</artifactId>
-      <scope>test</scope>
-    </dependency>
+     <!-- and for testing need annotations; but should be available via `jackson-databind` above -->
   </dependencies>
 
   <build>

release-notes/VERSION-2.x

@@ -10,6 +10,8 @@ Modules:
 
 2.10.0 (not yet released)
 
+#50: (yaml) Empty string serialized without quotes if MINIMIZE_QUOTES is enabled
+ (reported by tim-palmer@github)
 #100: (properties) Add an option to specify properties prefix
  (contributed by Alon B-L)
 #101: (yaml) Use latest SnakeYAML version 1.24 and get rid of deprecated methods

yaml/pom.xml

@@ -33,12 +33,8 @@
       <version>1.24</version>
     </dependency>
 
-     <!-- and for testing need annotations -->
-    <dependency>
-      <groupId>com.fasterxml.jackson.core</groupId>
-      <artifactId>jackson-annotations</artifactId>
-      <scope>test</scope>
-    </dependency>
+     <!-- and for testing need annotations; but should be available via `jackson-databind` above
+       -->
   </dependencies>
 
   <build>

yaml/src/main/java/com/fasterxml/jackson/dataformat/yaml/YAMLGenerator.java

@@ -588,25 +588,37 @@ public void writeString(String text) throws IOException,JsonGenerationException
             return;
         }
         _verifyValueWrite("write String value");
-        DumperOptions.ScalarStyle style = STYLE_QUOTED;
-        if (Feature.MINIMIZE_QUOTES.enabledIn(_formatFeatures) && !isBooleanContent(text)) {
+        DumperOptions.ScalarStyle style;
+
+        // [dataformats-text#50]: Empty String always quoted
+        if (text.isEmpty()) {
+            style = STYLE_QUOTED;
+        } else if (Feature.MINIMIZE_QUOTES.enabledIn(_formatFeatures)) {
+            if (isBooleanContent(text)) {
+                style = STYLE_QUOTED;
             // If this string could be interpreted as a number, it must be quoted.
-            if (Feature.ALWAYS_QUOTE_NUMBERS_AS_STRINGS.enabledIn(_formatFeatures)
+            } else if (Feature.ALWAYS_QUOTE_NUMBERS_AS_STRINGS.enabledIn(_formatFeatures)
                     && PLAIN_NUMBER_P.matcher(text).matches()) {
                 style = STYLE_QUOTED;
             } else if (text.indexOf('\n') >= 0) {
                 style = STYLE_LITERAL;
             } else {
                 style = STYLE_PLAIN;
             }
-        } else if (Feature.LITERAL_BLOCK_STYLE.enabledIn(_formatFeatures) && text.indexOf('\n') >= 0) {
-            style = STYLE_LITERAL;
+            _writeScalar(text, "string", style);
+            return;
+        } else {
+            if (Feature.LITERAL_BLOCK_STYLE.enabledIn(_formatFeatures) && text.indexOf('\n') >= 0) {
+                style = STYLE_LITERAL;
+            } else {
+                style = STYLE_QUOTED;
+            }
         }
         _writeScalar(text, "string", style);
     }
 
     private boolean isBooleanContent(String text) {
-        return text.equals("true") || text.equals("false");
+        return "true".equals(text) || "false".equals(text);
     }
 
     @Override

yaml/src/test/java/com/fasterxml/jackson/dataformat/yaml/failing/GeneratorWithMinimize50Test.java

@@ -127,4 +127,14 @@ public void testNonQuoteNumberStoredAsString() throws Exception
         assertEquals("---\n" +
                 "key: 2.0.1.2.3", yaml);
     }
+
+    // [dataformats-test#50]
+    public void testEmptyStringWithMinimizeQuotes() throws Exception
+    {
+        Map<String, Object> content = new HashMap<>();
+        content.put("key", "");
+        String yaml = MINIM_MAPPER.writeValueAsString(content).trim();
+
+        assertEquals("---\nkey: \"\"", yaml);
+    }
 }