Implemented AssertThatStringIsEmpty.

src/test/java/de/platon42/intellij/playground/Playground.java

@@ -1,5 +1,7 @@
 package de.platon42.intellij.playground;
 
+import org.assertj.core.api.AbstractStringAssert;
+
 import java.util.ArrayList;
 
 import static org.assertj.core.api.Assertions.assertThat;
@@ -48,4 +50,10 @@ public class Playground {
         assertThat("").isEqualTo(Boolean.TRUE);
     }
 
+    private void stringIsEmpty() {
+        String foo = "bar";
+        AbstractStringAssert<?> abstractStringAssert = assertThat(foo);
+        abstractStringAssert.isEqualTo("");
+    }
+
 }

src/test/java/de/platon42/intellij/plugins/cajon/inspections/AssertThatStringIsEmptyInspectionTest.kt

@@ -0,0 +1,21 @@
+package de.platon42.intellij.plugins.cajon.inspections
+
+import com.intellij.testFramework.fixtures.JavaCodeInsightTestFixture
+import de.platon42.intellij.jupiter.MyFixture
+import de.platon42.intellij.jupiter.TestDataSubPath
+import de.platon42.intellij.plugins.cajon.AbstractCajonTest
+import org.junit.jupiter.api.Test
+
+internal class AssertThatStringIsEmptyInspectionTest : AbstractCajonTest() {
+
+    @Test
+    @TestDataSubPath("inspections/StringIsEmpty")
+    internal fun assertThat_with_isEqualTo_emptyString_can_use_isEmpty(@MyFixture myFixture: JavaCodeInsightTestFixture) {
+        runTest {
+            myFixture.enableInspections(AssertThatStringIsEmptyInspection::class.java)
+            myFixture.configureByFile("StringIsEmptyBefore.java")
+            executeQuickFixes(myFixture, Regex("Replace is.*"), 1)
+            myFixture.checkResultByFile("StringIsEmptyAfter.java")
+        }
+    }
+}