Implemented AssertThatSizeInspection.

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

@@ -24,6 +24,11 @@ public class Playground {
         assertThat(new Long[1]).as("etc").isEmpty();
 
         assertThat(new ArrayList<>().size()).isEqualTo(1);
+        assertThat(new ArrayList<String>().size()).isEqualTo(1);
+        assertThat(new ArrayList<String>().size()).isGreaterThanOrEqualTo(1);
+        assertThat(new ArrayList<String>().size()).isZero();
+        assertThat(new ArrayList<String>()).hasSameSizeAs(new ArrayList<>());
+        assertThat(new Long[1]).as("etc").hasSameSizeAs(new Long[2]);
     }
 
     private void sizeOfArray() {
@@ -178,7 +183,6 @@ public class Playground {
         assertThat(new double[1]).as("array equals").containsExactly(new double[2], offset(1.0));
         assertThat(new float[1]).containsExactly(new float[2], offset(1.0f));
         assertThat(new float[1]).as("array equals").containsExactly(new float[2], offset(1.0f));
-
     }
 
 }

src/test/java/de/platon42/intellij/plugins/cajon/inspections/AssertThatSizeInspectionTest.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 AssertThatSizeInspectionTest : AbstractCajonTest() {
+
+    @Test
+    @TestDataSubPath("inspections/AssertThatSize")
+    internal fun assertThat_size_of_array_or_collection_can_be_simplified(@MyFixture myFixture: JavaCodeInsightTestFixture) {
+        runTest {
+            myFixture.enableInspections(AssertThatSizeInspection::class.java)
+            myFixture.configureByFile("AssertThatSizeBefore.java")
+            executeQuickFixes(myFixture, Regex("Replace .*"), 20)
+            myFixture.checkResultByFile("AssertThatSizeAfter.java")
+        }
+    }
+}

src/test/resources/inspections/AssertThatSize/AssertThatSizeAfter.java

@@ -0,0 +1,35 @@
+import java.util.ArrayList;
+
+import static org.assertj.core.api.Assertions.assertThat;
+
+public class assertThatSize {
+
+    private void assertThatSize() {
+        ArrayList<String> list = new ArrayList<>();
+        ArrayList<String> otherList = new ArrayList<>();
+        long[] array = new long[5];
+        long[] otherArray = new long[4];
+
+        assertThat(list).isEmpty();
+        assertThat(list).isEmpty();
+        assertThat(list).isNotEmpty();
+        assertThat(list).as("hi").isNotEmpty();
+        assertThat(list).isNotEmpty();
+        assertThat(list).isEmpty();
+        assertThat(list).isEmpty();
+        assertThat(list).hasSameSizeAs(otherList);
+        assertThat(list).hasSameSizeAs(array);
+        assertThat(list).hasSize(1);
+
+        assertThat(array).isEmpty();
+        assertThat(array).isEmpty();
+        assertThat(array).isNotEmpty();
+        assertThat(array).as("hi").isNotEmpty();
+        assertThat(array).isNotEmpty();
+        assertThat(array).isEmpty();
+        assertThat(array).isEmpty();
+        assertThat(array).hasSameSizeAs(list);
+        assertThat(array).hasSameSizeAs(otherArray);
+        assertThat(array).hasSize(1);
+    }
+}

src/test/resources/inspections/AssertThatSize/AssertThatSizeBefore.java

@@ -0,0 +1,35 @@
+import java.util.ArrayList;
+
+import static org.assertj.core.api.Assertions.assertThat;
+
+public class assertThatSize {
+
+    private void assertThatSize() {
+        ArrayList<String> list = new ArrayList<>();
+        ArrayList<String> otherList = new ArrayList<>();
+        long[] array = new long[5];
+        long[] otherArray = new long[4];
+
+        assertThat(list.size()).isEqualTo(0);
+        assertThat(list.size()).isZero();
+        assertThat(list.size()).isNotZero();
+        assertThat(list.size()).as("hi").isGreaterThan(0);
+        assertThat(list.size()).isGreaterThanOrEqualTo(1);
+        assertThat(list.size()).isLessThan(1);
+        assertThat(list.size()).isLessThanOrEqualTo(0);
+        assertThat(list.size()).isEqualTo(otherList.size());
+        assertThat(list.size()).isEqualTo(array.length);
+        assertThat(list.size()).isEqualTo(1);
+
+        assertThat(array.length).isEqualTo(0);
+        assertThat(array.length).isZero();
+        assertThat(array.length).isNotZero();
+        assertThat(array.length).as("hi").isGreaterThan(0);
+        assertThat(array.length).isGreaterThanOrEqualTo(1);
+        assertThat(array.length).isLessThan(1);
+        assertThat(array.length).isLessThanOrEqualTo(0);
+        assertThat(array.length).isEqualTo(list.size());
+        assertThat(array.length).isEqualTo(otherArray.length);
+        assertThat(array.length).isEqualTo(1);
+    }
+}

src/test/resources/inspections/JUnitAssertToAssertJ/JUnitAssertToAssertJInspectionAfter.java

@@ -2,9 +2,9 @@ import static org.assertj.core.api.Assertions.assertThat;
 import static org.assertj.core.data.Offset.offset;
 import static org.junit.Assert.*;
 
-public class JUnitAssertToAssertJInspection {
+public class JUnitAssertToAssertJ {
 
-    private void jUnitAssertToAssertJInspection() {
+    private void jUnitAssertToAssertJ() {
         String foo = "foo";
         String bar = "bar";
         assertThat(foo == "foo").isTrue();

src/test/resources/inspections/JUnitAssertToAssertJ/JUnitAssertToAssertJInspectionBefore.java

@@ -1,8 +1,8 @@
 import static org.junit.Assert.*;
 
-public class JUnitAssertToAssertJInspection {
+public class JUnitAssertToAssertJ {
 
-    private void jUnitAssertToAssertJInspection() {
+    private void jUnitAssertToAssertJ() {
         String foo = "foo";
         String bar = "bar";
         assertTrue(foo == "foo");