ESQL: Add url_encode function

- Remove url_encode from docs since it's a snapshot function
- Declare it along other snapshot functions in EsqlFunctionRegistry
- Annotate UrlEncode similarly to other snapshot functions
- Add url_encode capability to csv tests

Author: mouhc1ne

docs/reference/query-languages/esql/_snippets/functions/layout/url_encode.md

@@ -25,4 +25,3 @@
 * [`TO_LOWER`](../../functions-operators/string-functions.md#esql-to_lower)
 * [`TO_UPPER`](../../functions-operators/string-functions.md#esql-to_upper)
 * [`TRIM`](../../functions-operators/string-functions.md#esql-trim)
-* [`URL_ENCODE`](../../functions-operators/string-functions.md#esql-url_encode)

docs/reference/query-languages/esql/_snippets/lists/string-functions.md

@@ -93,6 +93,3 @@ mapped_pages:
 :::{include} ../_snippets/functions/layout/trim.md
 :::
 
-:::{include} ../_snippets/functions/layout/url_encode.md
-:::
-

docs/reference/query-languages/esql/functions-operators/string-functions.md

@@ -2481,6 +2481,8 @@ https%3A%2F%2Fwww.example.com%2Fpapers%3Fq%3Dinformation%2Bretrieval%26year%3D20
 ;
 
 url_encode mixed functions tests
+required_capability: url_encode
+
 FROM employees 
 | WHERE emp_no == 10001 
 | EVAL a = TRIM(URL_ENCODE(first_name))
@@ -2492,6 +2494,8 @@ Georgi    | georgi
 ;
 
 url_encode mixed input tests
+required_capability: url_encode
+
 ROW u = ["hello elastic!", "a+b-c%d", "", "!#$&'()*+,/:;=?@[]"] | EVAL u = URL_ENCODE(u);
 
 u:keyword

docs/reference/query-languages/esql/kibana/definition/functions/url_encode.json

@@ -449,8 +449,7 @@ private static FunctionDefinition[][] functions() {
                 def(ToString.class, ToString::new, "to_string", "to_str"),
                 def(ToTimeDuration.class, ToTimeDuration::new, "to_timeduration"),
                 def(ToUnsignedLong.class, ToUnsignedLong::new, "to_unsigned_long", "to_ulong", "to_ul"),
-                def(ToVersion.class, ToVersion::new, "to_version", "to_ver"),
-                def(UrlEncode.class, UrlEncode::new, "url_encode"), },
+                def(ToVersion.class, ToVersion::new, "to_version", "to_ver"), },
             // multivalue functions
             new FunctionDefinition[] {
                 def(MvAppend.class, MvAppend::new, "mv_append"),
@@ -515,7 +514,8 @@ private static FunctionDefinition[][] snapshotFunctions() {
                 def(L1Norm.class, L1Norm::new, "v_l1_norm"),
                 def(L2Norm.class, L2Norm::new, "v_l2_norm"),
                 def(Magnitude.class, Magnitude::new, "v_magnitude"),
-                def(Hamming.class, Hamming::new, "v_hamming") } };
+                def(Hamming.class, Hamming::new, "v_hamming"),
+                def(UrlEncode.class, UrlEncode::new, "url_encode") } };
     }
 
     public EsqlFunctionRegistry snapshotRegistry() {

x-pack/plugin/esql/qa/testFixtures/src/main/resources/string.csv-spec

@@ -17,6 +17,8 @@
 import org.elasticsearch.xpack.esql.core.tree.NodeInfo;
 import org.elasticsearch.xpack.esql.core.tree.Source;
 import org.elasticsearch.xpack.esql.expression.function.Example;
+import org.elasticsearch.xpack.esql.expression.function.FunctionAppliesTo;
+import org.elasticsearch.xpack.esql.expression.function.FunctionAppliesToLifecycle;
 import org.elasticsearch.xpack.esql.expression.function.FunctionInfo;
 import org.elasticsearch.xpack.esql.expression.function.Param;
 import org.elasticsearch.xpack.esql.expression.function.scalar.UnaryScalarFunction;
@@ -42,8 +44,10 @@ private UrlEncode(StreamInput in) throws IOException {
 
     @FunctionInfo(
         returnType = "keyword",
+        preview = true,
         description = "URL encodes the input.",
-        examples = { @Example(file = "string", tag = "url_encode") }
+        examples = { @Example(file = "string", tag = "url_encode") },
+        appliesTo = { @FunctionAppliesTo(lifeCycle = FunctionAppliesToLifecycle.DEVELOPMENT) }
     )
     public UrlEncode(Source source, @Param(name = "string", type = { "keyword", "text" }, description = "URL to encode.") Expression str) {
         super(source, str);

x-pack/plugin/esql/src/main/java/org/elasticsearch/xpack/esql/expression/function/EsqlFunctionRegistry.java

@@ -23,6 +23,7 @@
 import java.nio.charset.StandardCharsets;
 import java.util.ArrayList;
 import java.util.List;
+import java.util.Locale;
 import java.util.function.Supplier;
 
 import static org.hamcrest.Matchers.equalTo;
@@ -93,11 +94,11 @@ private static TestCaseSupplier.TestCase createTestCaseWithRandomString(
 
     private static RandomUrl generateRandomUrl() {
         String protocol = randomFrom("http://", "https://", "");
-        String domain = String.format("%s.com", randomAlphaOfLengthBetween(3, 10));
+        String domain = String.format(Locale.ROOT, "%s.com", randomAlphaOfLengthBetween(3, 10));
         String path = randomFrom("", "/" + randomAlphanumericOfLength(5) + "/");
         String query = randomFrom("", "?" + randomAlphaOfLength(5) + "=" + randomAlphanumericOfLength(5));
 
-        String plain = String.format("%s%s%s%s", protocol, domain, path, query);
+        String plain = String.format(Locale.ROOT, "%s%s%s%s", protocol, domain, path, query);
         String encoded = URLEncoder.encode(plain, StandardCharsets.UTF_8);
 
         return new RandomUrl(plain, encoded);