Minor tweak wrt #68, leave out single-letter names

Author: cowtowncoder

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

@@ -175,8 +175,11 @@ private Feature(boolean defaultState) {
      * aliases for booleans, and we better quote such values as keys; although Jackson
      * itself has no problems dealing with them, some other tools do have.
      */
+    // 02-Apr-2019, tatu: Some names will look funny if escaped: let's leave out 
+    //    single letter case (esp so 'y' won't get escaped)
     private final static Set<String> RESERVED_NAMES = new HashSet<>(Arrays.asList(
-            "y", "Y", "yes", "Yes", "YES", "n", "N", "no", "No", "NO",
+//            "y", "Y", "n", "N",
+            "yes", "Yes", "YES", "no", "No", "NO",
             "true", "True", "TRUE", "false", "False", "FALSE",
             "on", "On", "ON", "off", "Off", "OFF"
     ));

yaml/src/test/java/com/fasterxml/jackson/dataformat/yaml/misc/ReservedNamesTest.java

@@ -15,10 +15,10 @@ public void testQuotingOfBooleanKeys() throws Exception
         for (String value : new String[] {
                 "true", "True",
                 "false", "False",
-                "yes", "y", "Y",
-                "no", "n", "N",
-                "on",
-                "off",
+                "yes", "no",
+                // NOTE: single-letter cases left out on purpose
+//                "y", "Y", "n", "N",
+                "on", "off",
         }) {
             _testQuotingOfBooleanKeys(value);
         }

yaml/src/test/java/com/fasterxml/jackson/dataformat/yaml/ser/DatabindWriteTest.java

@@ -9,18 +9,31 @@
 import java.util.Map;
 import java.util.TreeSet;
 
+import com.fasterxml.jackson.annotation.JsonPropertyOrder;
 import com.fasterxml.jackson.databind.ObjectMapper;
 import com.fasterxml.jackson.databind.node.ObjectNode;
 import com.fasterxml.jackson.dataformat.yaml.ModuleTestBase;
 
 public class DatabindWriteTest extends ModuleTestBase
 {
+    final ObjectMapper MAPPER = newObjectMapper();
+
+    @JsonPropertyOrder(alphabetic = true)
+    static class Point {
+        public int x, y;
+
+        protected Point() { }
+        public Point(int x, int y) {
+            this.x = x;
+            this.y = y;
+        }
+    }
+
     public void testBasicPOJO() throws Exception
     {
-        ObjectMapper mapper = newObjectMapper();
         FiveMinuteUser user = new FiveMinuteUser("Bob", "Dabolito", false,
                 FiveMinuteUser.Gender.MALE, new byte[] { 1, 3, 13, 79 });
-        String yaml = mapper.writeValueAsString(user).trim();
+        String yaml = MAPPER.writeValueAsString(user).trim();
         String[] parts = yaml.split("\n");
         // unify ordering, need to use TreeSets to get alphabetic ordering
         TreeSet<String> exp = new TreeSet<String>();
@@ -45,14 +58,27 @@ public void testBasicPOJO() throws Exception
         assertFalse(it.hasNext());
     }
 
+    // Related to [dataformats-test#68], escaping of "reserved" names
+    public void testBasicDatabind2() throws Exception
+    {
+        String yaml = trimDocMarker(MAPPER.writeValueAsString(new Point(1, 2)));
+
+        // Just verify 'y' will NOT be escaped
+        assertEquals("x: 1\ny: 2", yaml);
+
+        // Actually let's try reading back, too
+        Point p = MAPPER.readValue(yaml, Point.class);
+        assertEquals(1, p.x);
+        assertEquals(2, p.y);
+    }
+    
     public void testWithFile() throws Exception
     {
         File f = File.createTempFile("test", ".yml");
         f.deleteOnExit();
-        ObjectMapper mapper = newObjectMapper();
         Map<String,Integer> map = new HashMap<String,Integer>();
         map.put("a", 3);
-        mapper.writeValue(f, map);
+        MAPPER.writeValue(f, map);
         assertTrue(f.canRead());
         BufferedReader br = new BufferedReader(new InputStreamReader(new FileInputStream(
                 f), "UTF-8"));
@@ -71,13 +97,12 @@ public void testWithFile2() throws Exception
     {
         File f = File.createTempFile("test", ".yml");
         f.deleteOnExit();
-        ObjectMapper mapper = newObjectMapper();
-        ObjectNode root = mapper.createObjectNode();
+        ObjectNode root = MAPPER.createObjectNode();
         root.put("name", "Foobar");
-        mapper.writeValue(f, root);
+        MAPPER.writeValue(f, root);
 
         // and get it back
-        Map<?,?> result = mapper.readValue(f, Map.class);
+        Map<?,?> result = MAPPER.readValue(f, Map.class);
         assertEquals(1, result.size());
         assertEquals("Foobar", result.get("name"));
     }