Allow query operators to be used with ONE query expression element (#516)

Fixes #515

Author: mojito317

CHANGES.md

@@ -1,3 +1,7 @@
+# Unreleased
+- [FIXED] Allow `$and`, `$or`, and `$nor` operator selectors
+  to be used with only one expression selector.
+
 # 2.19.1 (2020-07-03)
 - [FIXED] Connection leak regression introduced in 2.18.0 caused by not closing streams from
   successful session response bodies.
@@ -296,7 +300,7 @@
 - [FIXED] `NullPointerException` when parsing `{doc: null}` JSON in search or view results.
 - [FIXED] Fixed issue with pagination numbering when using `queryPage` with
   a clustered DB.
-- [FIXED] Fixed issue where `queryPage` could not handle JSON values emitted from views.  
+- [FIXED] Fixed issue where `queryPage` could not handle JSON values emitted from views.
 - [IMPROVED] Various documentation updates.
 - [DEPRECATED] `com.cloudant.client.api.model.Page` setter methods.
 

cloudant-client/src/main/java/com/cloudant/client/api/query/Operation.java

@@ -80,7 +80,7 @@ public static Operation nor(Selector... rhs) {
     @Override
     public String toString() {
         // op rhs format ($and etc)
-        return String.format("\"%s\": %s", this.op, quoteCurly(this.rhs));
+        return String.format("\"%s\": %s", this.op, quoteCurly(this.rhs, this.op));
     }
 
 }

cloudant-client/src/main/java/com/cloudant/client/internal/query/Helpers.java

@@ -1,5 +1,5 @@
 /*
- * Copyright © 2017, 2018 IBM Corp. All rights reserved.
+ * Copyright © 2017, 2020 IBM Corp. All rights reserved.
  *
  * Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file
  * except in compliance with the License. You may obtain a copy of the License at
@@ -59,6 +59,14 @@ public static String quoteNoSquare(Object[] os) {
         return quoteInternal(os, ", ", "", "", "", "");
     }
 
+    public static String quoteCurly(Object[] os, String op) {
+        if (op.equals("$not")) {
+            // the operation "not" only takes one argument, so we don't need to make an array
+            return String.format("%s%s%s", "{", quote(os[0]), "}");
+        }
+        return quoteInternal(os, ", ", "{", "}", "[", "]");
+    }
+
     public static String quoteCurly(Object[] os) {
         if (os.length == 1) {
             // the operation "not" only takes one argument, so we don't need to make an array

cloudant-client/src/test/java/com/cloudant/tests/QueryTests.java

@@ -1,5 +1,5 @@
 /*
- * Copyright © 2017, 2018 IBM Corp. All rights reserved.
+ * Copyright © 2017, 2020 IBM Corp. All rights reserved.
  *
  * Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file
  * except in compliance with the License. You may obtain a copy of the License at
@@ -57,6 +57,15 @@ public void basicSelector2() {
                 "{\"location\": {\"$eq\": \"Boston\"}}]}}", qb.build());
     }
 
+    // "And selector with only one field"
+    @Test
+    public void basicSelector2WithOneField() {
+        QueryBuilder qb = new QueryBuilder(and(
+                eq("name", "Paul")));
+        Assertions.assertEquals("{\"selector\": " +
+                "{\"$and\": [{\"name\": {\"$eq\": \"Paul\"}}]}}", qb.build());
+    }
+
     // "SUBFIELDS"
     @Test
     public void basicSelector3() {