From e860de0637779c987e121a2328b55a73990e8faf Mon Sep 17 00:00:00 2001
From: Rick Ossendrijver <rick.ossendrijver@gmail.com>
Date: Thu, 25 Jan 2024 08:57:33 +0100
Subject: [PATCH] Disallow static import of {Mono,Flux} and partially allow
 `empty`

---
 .../picnic/errorprone/bugpatterns/NonStaticImport.java     | 7 +++++--
 .../picnic/errorprone/bugpatterns/NonStaticImportTest.java | 3 +++
 .../picnic/errorprone/bugpatterns/StaticImportTest.java    | 3 +++
 3 files changed, 11 insertions(+), 2 deletions(-)

diff --git a/error-prone-contrib/src/main/java/tech/picnic/errorprone/bugpatterns/NonStaticImport.java b/error-prone-contrib/src/main/java/tech/picnic/errorprone/bugpatterns/NonStaticImport.java
index bacf57fbe56..41d951ccdae 100644
--- a/error-prone-contrib/src/main/java/tech/picnic/errorprone/bugpatterns/NonStaticImport.java
+++ b/error-prone-contrib/src/main/java/tech/picnic/errorprone/bugpatterns/NonStaticImport.java
@@ -33,6 +33,7 @@
 import java.time.ZoneOffset;
 import java.util.Collections;
 import java.util.Locale;
+import java.util.Optional;
 import java.util.regex.Pattern;
 import org.jspecify.annotations.Nullable;
 import tech.picnic.errorprone.bugpatterns.util.SourceCode;
@@ -71,7 +72,9 @@ public final class NonStaticImport extends BugChecker implements CompilationUnit
           Strings.class.getCanonicalName(),
           VisitorState.class.getCanonicalName(),
           ZoneOffset.class.getCanonicalName(),
-          "com.google.errorprone.BugCheckerRefactoringTestHelper.TestMode");
+          "com.google.errorprone.BugCheckerRefactoringTestHelper.TestMode",
+          "reactor.core.publisher.Flux",
+          "reactor.core.publisher.Mono");
 
   /**
    * Type members that should never be statically imported.
@@ -103,6 +106,7 @@ public final class NonStaticImport extends BugChecker implements CompilationUnit
               "sort",
               "swap")
           .put(Locale.class.getCanonicalName(), "ROOT")
+          .put(Optional.class.getCanonicalName(), "empty")
           .putAll(Pattern.class.getCanonicalName(), "compile", "matches", "quote")
           .put(Predicates.class.getCanonicalName(), "contains")
           .put("org.springframework.http.MediaType", "ALL")
@@ -125,7 +129,6 @@ public final class NonStaticImport extends BugChecker implements CompilationUnit
           "builder",
           "copyOf",
           "create",
-          "empty",
           "from",
           "getDefaultInstance",
           "INSTANCE",
diff --git a/error-prone-contrib/src/test/java/tech/picnic/errorprone/bugpatterns/NonStaticImportTest.java b/error-prone-contrib/src/test/java/tech/picnic/errorprone/bugpatterns/NonStaticImportTest.java
index 86ef74d4e6f..fc810fbf0e4 100644
--- a/error-prone-contrib/src/test/java/tech/picnic/errorprone/bugpatterns/NonStaticImportTest.java
+++ b/error-prone-contrib/src/test/java/tech/picnic/errorprone/bugpatterns/NonStaticImportTest.java
@@ -65,6 +65,8 @@ void identification() {
             "// BUG: Diagnostic contains:",
             "import static java.util.Optional.empty;",
             "import static pkg.A.WithMethodThatIsSelectivelyFlagged.list;",
+            "// BUG: Diagnostic contains:",
+            "import static reactor.core.publisher.Flux.just;",
             "",
             "import com.google.common.collect.ImmutableList;",
             "import com.google.common.collect.ImmutableSet;",
@@ -90,6 +92,7 @@ void identification() {
             "    Locale english = ENGLISH;",
             "    Locale root = ROOT;",
             "    empty();",
+            "    just();",
             "",
             "    list();",
             "    new ZERO();",
diff --git a/error-prone-contrib/src/test/java/tech/picnic/errorprone/bugpatterns/StaticImportTest.java b/error-prone-contrib/src/test/java/tech/picnic/errorprone/bugpatterns/StaticImportTest.java
index 4dde83f6e1c..9ac112a7a6a 100644
--- a/error-prone-contrib/src/test/java/tech/picnic/errorprone/bugpatterns/StaticImportTest.java
+++ b/error-prone-contrib/src/test/java/tech/picnic/errorprone/bugpatterns/StaticImportTest.java
@@ -47,6 +47,7 @@ void identification() {
             "import com.google.common.collect.ImmutableSet;",
             "import com.google.errorprone.refaster.ImportPolicy;",
             "import com.google.errorprone.refaster.annotation.UseImportPolicy;",
+            "import com.mongodb.client.model.Filters;",
             "import java.nio.charset.StandardCharsets;",
             "import java.time.ZoneOffset;",
             "import java.util.Optional;",
@@ -99,6 +100,8 @@ void identification() {
             "    // BUG: Diagnostic contains:",
             "    MediaType t2 = MediaType.APPLICATION_JSON;",
             "",
+            "    // BUG: Diagnostic contains:",
+            "    Filters.empty();",
             "    Optional.empty();",
             "",
             "    // BUG: Diagnostic contains:",