diff --git a/src/main/java/com/exasol/adapter/sql/SqlUtils.java b/src/main/java/com/exasol/adapter/sql/SqlUtils.java
index 5f37a495..f487cdd4 100644
--- a/src/main/java/com/exasol/adapter/sql/SqlUtils.java
+++ b/src/main/java/com/exasol/adapter/sql/SqlUtils.java
@@ -3,11 +3,13 @@
 import java.util.Map;
 
 public final class SqlUtils {
-    private SqlUtils(){
+    private SqlUtils() {
         //Intentionally left blank
     }
 
-    public static String quoteIdentifierIfNeeded(final String identifier, final Map<String, ?> config) {
+    @SuppressWarnings("squid:S1157")
+    public static String quoteIdentifierIfNeeded(final String identifier,
+          final Map<String, ?> config) {
         String quoteChar = "\"";
         if (config.containsKey("QUOTE_CHAR")) {
             quoteChar = config.get("QUOTE_CHAR").toString();
diff --git a/src/test/java/com/exasol/adapter/sql/SqlPredicateEqualTest.java b/src/test/java/com/exasol/adapter/sql/SqlPredicateEqualTest.java
new file mode 100644
index 00000000..bda7584c
--- /dev/null
+++ b/src/test/java/com/exasol/adapter/sql/SqlPredicateEqualTest.java
@@ -0,0 +1,51 @@
+package com.exasol.adapter.sql;
+
+import com.exasol.adapter.AdapterException;
+import org.junit.jupiter.api.BeforeEach;
+import org.junit.jupiter.api.Test;
+
+import static org.hamcrest.CoreMatchers.equalTo;
+import static org.hamcrest.MatcherAssert.assertThat;
+import static org.mockito.Mockito.mock;
+import static org.mockito.Mockito.when;
+
+class SqlPredicateEqualTest {
+    private SqlPredicateEqual sqlPredicateEqual;
+    private SqlLiteralDouble sqlLiteralDoubleLeft;
+    private SqlLiteralDouble sqlLiteralDoubleRight;
+
+    @BeforeEach
+    void setUp() {
+        this.sqlLiteralDoubleLeft = new SqlLiteralDouble(20.5);
+        this.sqlLiteralDoubleRight = new SqlLiteralDouble(20.5);
+        this.sqlPredicateEqual =
+              new SqlPredicateEqual(this.sqlLiteralDoubleLeft, this.sqlLiteralDoubleRight);
+    }
+
+    @Test
+    void testToSimpleSql() {
+        assertThat(this.sqlPredicateEqual.toSimpleSql(), equalTo("20.5 = 20.5"));
+    }
+
+    @Test
+    void testGetType() {
+        assertThat(this.sqlPredicateEqual.getType(), equalTo(SqlNodeType.PREDICATE_EQUAL));
+    }
+
+    @Test
+    void testAccept() throws AdapterException {
+        final SqlNodeVisitor<SqlPredicateEqual> visitor = mock(SqlNodeVisitor.class);
+        when(visitor.visit(this.sqlPredicateEqual)).thenReturn(this.sqlPredicateEqual);
+        assertThat(this.sqlPredicateEqual.accept(visitor), equalTo(this.sqlPredicateEqual));
+    }
+
+    @Test
+    void testGetLeft() {
+        assertThat(this.sqlPredicateEqual.getLeft(), equalTo(this.sqlLiteralDoubleLeft));
+    }
+
+    @Test
+    void testGetRight() {
+        assertThat(this.sqlPredicateEqual.getRight(), equalTo(this.sqlLiteralDoubleRight));
+    }
+}
\ No newline at end of file
diff --git a/src/test/java/com/exasol/adapter/sql/SqlPredicateLessEqualTest.java b/src/test/java/com/exasol/adapter/sql/SqlPredicateLessEqualTest.java
new file mode 100644
index 00000000..21ba67b8
--- /dev/null
+++ b/src/test/java/com/exasol/adapter/sql/SqlPredicateLessEqualTest.java
@@ -0,0 +1,52 @@
+package com.exasol.adapter.sql;
+
+import com.exasol.adapter.AdapterException;
+import org.junit.jupiter.api.BeforeEach;
+import org.junit.jupiter.api.Test;
+
+import static org.hamcrest.CoreMatchers.equalTo;
+import static org.hamcrest.MatcherAssert.assertThat;
+import static org.mockito.Mockito.mock;
+import static org.mockito.Mockito.when;
+
+class SqlPredicateLessEqualTest {
+    private SqlPredicateLessEqual sqlPredicateLessEqual;
+    private SqlLiteralDouble sqlLiteralDoubleLeft;
+    private SqlLiteralDouble sqlLiteralDoubleRight;
+
+    @BeforeEach
+    void setUp() {
+        this.sqlLiteralDoubleLeft = new SqlLiteralDouble(20.5);
+        this.sqlLiteralDoubleRight = new SqlLiteralDouble(21.5);
+        this.sqlPredicateLessEqual =
+              new SqlPredicateLessEqual(this.sqlLiteralDoubleLeft, this.sqlLiteralDoubleRight);
+    }
+
+    @Test
+    void testToSimpleSql() {
+        assertThat(this.sqlPredicateLessEqual.toSimpleSql(), equalTo("20.5 <= 21.5"));
+    }
+
+    @Test
+    void testGetType() {
+        assertThat(this.sqlPredicateLessEqual.getType(), equalTo(SqlNodeType.PREDICATE_LESSEQUAL));
+    }
+
+    @Test
+    void testAccept() throws AdapterException {
+        final SqlNodeVisitor<SqlPredicateLessEqual> visitor = mock(SqlNodeVisitor.class);
+        when(visitor.visit(this.sqlPredicateLessEqual)).thenReturn(this.sqlPredicateLessEqual);
+        assertThat(this.sqlPredicateLessEqual.accept(visitor), equalTo(this.sqlPredicateLessEqual));
+    }
+
+    @Test
+    void testGetLeft() {
+        assertThat(this.sqlPredicateLessEqual.getLeft(), equalTo(this.sqlLiteralDoubleLeft));
+    }
+
+    @Test
+    void testGetRight() {
+        assertThat(this.sqlPredicateLessEqual.getRight(), equalTo(this.sqlLiteralDoubleRight));
+    }
+
+}
\ No newline at end of file
diff --git a/src/test/java/com/exasol/adapter/sql/SqlPredicateLessTest.java b/src/test/java/com/exasol/adapter/sql/SqlPredicateLessTest.java
new file mode 100644
index 00000000..2c413c06
--- /dev/null
+++ b/src/test/java/com/exasol/adapter/sql/SqlPredicateLessTest.java
@@ -0,0 +1,51 @@
+package com.exasol.adapter.sql;
+
+import com.exasol.adapter.AdapterException;
+import org.junit.jupiter.api.BeforeEach;
+import org.junit.jupiter.api.Test;
+
+import static org.hamcrest.CoreMatchers.equalTo;
+import static org.hamcrest.MatcherAssert.assertThat;
+import static org.mockito.Mockito.mock;
+import static org.mockito.Mockito.when;
+
+class SqlPredicateLessTest {
+    private SqlPredicateLess sqlPredicateLess;
+    private SqlLiteralDouble sqlLiteralDoubleLeft;
+    private SqlLiteralDouble sqlLiteralDoubleRight;
+
+    @BeforeEach
+    void setUp() {
+        this.sqlLiteralDoubleLeft = new SqlLiteralDouble(20.5);
+        this.sqlLiteralDoubleRight = new SqlLiteralDouble(21.5);
+        this.sqlPredicateLess =
+              new SqlPredicateLess(this.sqlLiteralDoubleLeft, this.sqlLiteralDoubleRight);
+    }
+
+    @Test
+    void testToSimpleSql() {
+        assertThat(this.sqlPredicateLess.toSimpleSql(), equalTo("20.5 < 21.5"));
+    }
+
+    @Test
+    void testGetType() {
+        assertThat(this.sqlPredicateLess.getType(), equalTo(SqlNodeType.PREDICATE_LESS));
+    }
+
+    @Test
+    void testAccept() throws AdapterException {
+        final SqlNodeVisitor<SqlPredicateLess> visitor = mock(SqlNodeVisitor.class);
+        when(visitor.visit(this.sqlPredicateLess)).thenReturn(this.sqlPredicateLess);
+        assertThat(this.sqlPredicateLess.accept(visitor), equalTo(this.sqlPredicateLess));
+    }
+
+    @Test
+    void testGetLeft() {
+        assertThat(this.sqlPredicateLess.getLeft(), equalTo(this.sqlLiteralDoubleLeft));
+    }
+
+    @Test
+    void testGetRight() {
+        assertThat(this.sqlPredicateLess.getRight(), equalTo(this.sqlLiteralDoubleRight));
+    }
+}
\ No newline at end of file
diff --git a/src/test/java/com/exasol/adapter/sql/SqlPredicateNotEqualTest.java b/src/test/java/com/exasol/adapter/sql/SqlPredicateNotEqualTest.java
new file mode 100644
index 00000000..bc41149c
--- /dev/null
+++ b/src/test/java/com/exasol/adapter/sql/SqlPredicateNotEqualTest.java
@@ -0,0 +1,51 @@
+package com.exasol.adapter.sql;
+
+import com.exasol.adapter.AdapterException;
+import org.junit.jupiter.api.BeforeEach;
+import org.junit.jupiter.api.Test;
+
+import static org.hamcrest.CoreMatchers.equalTo;
+import static org.hamcrest.MatcherAssert.assertThat;
+import static org.mockito.Mockito.mock;
+import static org.mockito.Mockito.when;
+
+class SqlPredicateNotEqualTest {
+    private SqlPredicateNotEqual sqlPredicateNotEqual;
+    private SqlLiteralDouble sqlLiteralDoubleLeft;
+    private SqlLiteralDouble sqlLiteralDoubleRight;
+
+    @BeforeEach
+    void setUp() {
+        this.sqlLiteralDoubleLeft = new SqlLiteralDouble(21.5);
+        this.sqlLiteralDoubleRight = new SqlLiteralDouble(20.5);
+        this.sqlPredicateNotEqual =
+              new SqlPredicateNotEqual(this.sqlLiteralDoubleLeft, this.sqlLiteralDoubleRight);
+    }
+
+    @Test
+    void testToSimpleSql() {
+        assertThat(this.sqlPredicateNotEqual.toSimpleSql(), equalTo("21.5 != 20.5"));
+    }
+
+    @Test
+    void testGetType() {
+        assertThat(this.sqlPredicateNotEqual.getType(), equalTo(SqlNodeType.PREDICATE_NOTEQUAL));
+    }
+
+    @Test
+    void testAccept() throws AdapterException {
+        final SqlNodeVisitor<SqlPredicateNotEqual> visitor = mock(SqlNodeVisitor.class);
+        when(visitor.visit(this.sqlPredicateNotEqual)).thenReturn(this.sqlPredicateNotEqual);
+        assertThat(this.sqlPredicateNotEqual.accept(visitor), equalTo(this.sqlPredicateNotEqual));
+    }
+
+    @Test
+    void testGetLeft() {
+        assertThat(this.sqlPredicateNotEqual.getLeft(), equalTo(this.sqlLiteralDoubleLeft));
+    }
+
+    @Test
+    void testGetRight() {
+        assertThat(this.sqlPredicateNotEqual.getRight(), equalTo(this.sqlLiteralDoubleRight));
+    }
+}
\ No newline at end of file