Internally: Upgraded to AssertJ 13.2.2.

Support for hasSizeLessThan(), hasSizeLessThanOrEqualTo(), hasSizeGreaterThanOrEqualTo(), and hasSizeGreaterThan() for AssertThatSizeInspection (with AssertJ >=13.2.0).
Really fixed highlighting for JUnit conversion. Sorry.
Fixed testing code to work against IDEA 2019.1.

src/test/java/de/platon42/intellij/jupiter/LightCodeInsightExtension.java

@@ -131,7 +131,6 @@ public class LightCodeInsightExtension implements ParameterResolver, AfterTestEx
                 VirtualFile jarFile = LocalFileSystem.getInstance().findFileByIoFile(jarPath.toFile());
                 myFixture.allowTreeAccessForFile(jarFile);
                 PsiTestUtil.addLibrary(
-                        myFixture.getModule(),
                         model,
                         jarPath.getFileName().toString().replace(".jar", ""),
                         jarPath.getParent().toString(),

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

@@ -4,9 +4,11 @@ import org.assertj.core.api.ListAssert;
 import org.assertj.core.data.Offset;
 
 import java.util.ArrayList;
+import java.util.Optional;
 
 import static org.assertj.core.api.Assertions.assertThat;
 import static org.assertj.core.data.Offset.offset;
+import static org.assertj.guava.api.Assertions.assertThat;
 import static org.junit.Assert.*;
 
 public class Playground {
@@ -27,6 +29,7 @@ public class Playground {
         assertThat(new ArrayList<String>().size()).isEqualTo(1);
         assertThat(new ArrayList<String>().size()).isGreaterThanOrEqualTo(1);
         assertThat(new ArrayList<String>().size()).isZero();
+        assertThat(new ArrayList<String>()).hasSizeGreaterThan(1);
         assertThat(new ArrayList<String>()).hasSameSizeAs(new ArrayList<>());
         assertThat(new Long[1]).as("etc").hasSameSizeAs(new Long[2]);
     }
@@ -75,6 +78,30 @@ public class Playground {
         assertThat(foo).hasSize(0);
     }
 
+    private void java8Optional() {
+        Optional<String> foo = Optional.empty();
+        assertThat(foo.get()).isEqualTo("bla");
+        assertThat(foo).contains("bla");
+        assertThat(foo.isPresent()).isTrue();
+        assertThat(!foo.isPresent()).isFalse();
+        assertThat(foo).isPresent();
+        assertThat(foo.isPresent()).isFalse();
+        assertThat(!foo.isPresent()).isTrue();
+        assertThat(foo).isNotPresent();
+    }
+
+    private void guavaOptional() {
+        com.google.common.base.Optional<String> foo = com.google.common.base.Optional.absent();
+        assertThat(foo.get()).isEqualTo("bla");
+        assertThat(foo).contains("bla");
+        assertThat(foo.isPresent()).isTrue();
+        assertThat(!foo.isPresent()).isFalse();
+        assertThat(foo).isPresent();
+        assertThat(foo.isPresent()).isFalse();
+        assertThat(!foo.isPresent()).isTrue();
+        assertThat(foo).isAbsent();
+    }
+
     private void junitAssertions() {
         assertTrue(true);
         assertTrue("message", true);
@@ -183,6 +210,8 @@ 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));
+
+        assertThat(new Object()).extracting(Object::toString, Object::hashCode);
     }
 
 }

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

@@ -14,7 +14,7 @@ internal class AssertThatSizeInspectionTest : AbstractCajonTest() {
         runTest {
             myFixture.enableInspections(AssertThatSizeInspection::class.java)
             myFixture.configureByFile("AssertThatSizeBefore.java")
-            executeQuickFixes(myFixture, Regex("Replace .*"), 20)
+            executeQuickFixes(myFixture, Regex("Replace .*"), 28)
             myFixture.checkResultByFile("AssertThatSizeAfter.java")
         }
     }

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

@@ -2,7 +2,7 @@ import java.util.ArrayList;
 
 import static org.assertj.core.api.Assertions.assertThat;
 
-public class assertThatSize {
+public class AssertThatSize {
 
     private void assertThatSize() {
         ArrayList<String> list = new ArrayList<>();
@@ -20,6 +20,10 @@ public class assertThatSize {
         assertThat(list).hasSameSizeAs(otherList);
         assertThat(list).hasSameSizeAs(array);
         assertThat(list).hasSize(1);
+        assertThat(list).hasSizeGreaterThan(list.size() * 2);
+        assertThat(list).hasSizeGreaterThanOrEqualTo(list.size() * 2);
+        assertThat(list).hasSizeLessThan(list.size() * 2);
+        assertThat(list).hasSizeLessThanOrEqualTo(list.size() * 2);
 
         assertThat(array).isEmpty();
         assertThat(array).isEmpty();
@@ -31,5 +35,9 @@ public class assertThatSize {
         assertThat(array).hasSameSizeAs(list);
         assertThat(array).hasSameSizeAs(otherArray);
         assertThat(array).hasSize(1);
+        assertThat(array).hasSizeGreaterThan(otherArray.length - 1);
+        assertThat(array).hasSizeGreaterThanOrEqualTo(otherArray.length + 1);
+        assertThat(array).hasSizeLessThan(otherArray.length - 3);
+        assertThat(array).hasSizeLessThanOrEqualTo(1 - otherArray.length);
     }
 }

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

@@ -2,7 +2,7 @@ import java.util.ArrayList;
 
 import static org.assertj.core.api.Assertions.assertThat;
 
-public class assertThatSize {
+public class AssertThatSize {
 
     private void assertThatSize() {
         ArrayList<String> list = new ArrayList<>();
@@ -20,6 +20,10 @@ public class assertThatSize {
         assertThat(list.size()).isEqualTo(otherList.size());
         assertThat(list.size()).isEqualTo(array.length);
         assertThat(list.size()).isEqualTo(1);
+        assertThat(list.size()).isGreaterThan(list.size() * 2);
+        assertThat(list.size()).isGreaterThanOrEqualTo(list.size() * 2);
+        assertThat(list.size()).isLessThan(list.size() * 2);
+        assertThat(list.size()).isLessThanOrEqualTo(list.size() * 2);
 
         assertThat(array.length).isEqualTo(0);
         assertThat(array.length).isZero();
@@ -31,5 +35,9 @@ public class assertThatSize {
         assertThat(array.length).isEqualTo(list.size());
         assertThat(array.length).isEqualTo(otherArray.length);
         assertThat(array.length).isEqualTo(1);
+        assertThat(array.length).isGreaterThan(otherArray.length - 1);
+        assertThat(array.length).isGreaterThanOrEqualTo(otherArray.length + 1);
+        assertThat(array.length).isLessThan(otherArray.length - 3);
+        assertThat(array.length).isLessThanOrEqualTo(1 - otherArray.length);
     }
 }