Add testSenaryFunctionNoOptionalArguments to EsqlFunctionRegistryTests

Author: timgrein

x-pack/plugin/esql/src/test/java/org/elasticsearch/xpack/esql/expression/function/EsqlFunctionRegistryTests.java

@@ -71,6 +71,33 @@ public void testBinaryFunction() {
         assertThat(e.getMessage(), containsString("expects exactly two arguments"));
     }
 
+    public void testSenaryFunctionNoOptionalArguments(){
+        UnresolvedFunction unresolvedFunction = uf(DEFAULT, mock(Expression.class), mock(Expression.class), mock(Expression.class), mock(Expression.class), mock(Expression.class), mock(Expression.class));
+        EsqlFunctionRegistry registry = new EsqlFunctionRegistry(def(DummyFunction.class, (Source source, Expression exp1, Expression exp2, Expression exp3, Expression exp4, Expression exp5, Expression exp6) -> {
+            assertSame(exp1, unresolvedFunction.children().get(0));
+            assertSame(exp2, unresolvedFunction.children().get(1));
+            assertSame(exp3, unresolvedFunction.children().get(2));
+            assertSame(exp4, unresolvedFunction.children().get(3));
+            assertSame(exp5, unresolvedFunction.children().get(4));
+            assertSame(exp6, unresolvedFunction.children().get(5));
+
+            return new DummyFunction(source);
+        }, 0, "dummyFunction"));
+
+        FunctionDefinition def = registry.resolveFunction(unresolvedFunction.name());
+        assertEquals(unresolvedFunction.source(), unresolvedFunction.buildResolved(randomConfiguration(), def).source());
+
+        // No children aren't supported
+        ParsingException e = expectThrows(ParsingException.class, () -> uf(DEFAULT).buildResolved(randomConfiguration(), def));
+        assertThat(e.getMessage(), containsString("expects exactly six arguments"));
+
+        // One child isn't supported
+        e = expectThrows(ParsingException.class, () -> uf(DEFAULT, mock(Expression.class)).buildResolved(randomConfiguration(), def));
+        assertThat(e.getMessage(), containsString("expects exactly six arguments"));
+    }
+
+    // TODO: senary with optional
+
     public void testAliasNameIsTheSameAsAFunctionName() {
         EsqlFunctionRegistry r = new EsqlFunctionRegistry(def(DummyFunction.class, DummyFunction::new, "DUMMY_FUNCTION", "ALIAS"));
         QlIllegalArgumentException iae = expectThrows(