From 942265730ba326740f05829343f587de118b2a37 Mon Sep 17 00:00:00 2001
From: Sergey Opivalov <sopivalov@gradle.com>
Date: Fri, 21 Mar 2025 19:14:33 +0300
Subject: [PATCH] Support ETV for `SubtractingFileCollection`

---
 .../file/SubtractingFileCollection.java       | 24 +++++++
 ...ileCollectionExecutionTimeValueTest.groovy | 62 +++++++++++++++++++
 2 files changed, 86 insertions(+)
 create mode 100644 platforms/core-configuration/file-collections/src/test/groovy/org/gradle/api/internal/file/SubtractingFileCollectionExecutionTimeValueTest.groovy

diff --git a/platforms/core-configuration/file-collections/src/main/java/org/gradle/api/internal/file/SubtractingFileCollection.java b/platforms/core-configuration/file-collections/src/main/java/org/gradle/api/internal/file/SubtractingFileCollection.java
index e64c2205ea98..a07d53ab64d4 100644
--- a/platforms/core-configuration/file-collections/src/main/java/org/gradle/api/internal/file/SubtractingFileCollection.java
+++ b/platforms/core-configuration/file-collections/src/main/java/org/gradle/api/internal/file/SubtractingFileCollection.java
@@ -21,6 +21,7 @@
 
 import java.io.File;
 import java.util.LinkedHashSet;
+import java.util.Optional;
 import java.util.Set;
 
 public class SubtractingFileCollection extends AbstractOpaqueFileCollection {
@@ -58,8 +59,31 @@ protected Set<File> getIntrinsicFiles() {
         return files;
     }
 
+    @Override
+    public Optional<FileCollectionExecutionTimeValue> calculateExecutionTimeValue() {
+        return left.calculateExecutionTimeValue()
+            .flatMap(leftEtv -> ((FileCollectionInternal) right).calculateExecutionTimeValue()
+                .map(rightEtv -> new SubtractingExecutionTimeValue(leftEtv, rightEtv)));
+    }
+
     @Override
     public boolean contains(File file) {
         return left.contains(file) && !right.contains(file);
     }
+
+    private static class SubtractingExecutionTimeValue implements FileCollectionExecutionTimeValue {
+        private final FileCollectionExecutionTimeValue left;
+        private final FileCollectionExecutionTimeValue right;
+
+        private SubtractingExecutionTimeValue(FileCollectionExecutionTimeValue left, FileCollectionExecutionTimeValue right) {
+            this.left = left;
+            this.right = right;
+        }
+
+        @Override
+        public FileCollectionInternal toFileCollection(FileCollectionFactory fileCollectionFactory) {
+            return (FileCollectionInternal) left.toFileCollection(fileCollectionFactory)
+                .minus(right.toFileCollection(fileCollectionFactory));
+        }
+    }
 }
diff --git a/platforms/core-configuration/file-collections/src/test/groovy/org/gradle/api/internal/file/SubtractingFileCollectionExecutionTimeValueTest.groovy b/platforms/core-configuration/file-collections/src/test/groovy/org/gradle/api/internal/file/SubtractingFileCollectionExecutionTimeValueTest.groovy
new file mode 100644
index 000000000000..39f013041c13
--- /dev/null
+++ b/platforms/core-configuration/file-collections/src/test/groovy/org/gradle/api/internal/file/SubtractingFileCollectionExecutionTimeValueTest.groovy
@@ -0,0 +1,62 @@
+/*
+ * Copyright 2025 the original author or authors.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package org.gradle.api.internal.file
+
+
+import spock.lang.Specification
+
+import static org.gradle.api.internal.file.TestFiles.fileCollectionFactory
+
+class SubtractingFileCollectionExecutionTimeValueTest extends Specification {
+    def "SubtractingFileCollection supports execution time value"() {
+        given:
+        def left = fileCollectionFactory().fixed(new File("foo.txt"), new File("bar.txt"))
+        def right = fileCollectionFactory().fixed(new File("bar.txt"))
+        def collection = new SubtractingFileCollection(left, right)
+
+        when:
+        def executionTimeValue = collection.calculateExecutionTimeValue()
+
+        then:
+        executionTimeValue.present
+
+        and:
+        def newCollection = executionTimeValue.get().toFileCollection(fileCollectionFactory())
+
+        then:
+        newCollection.files == [new File("foo.txt")] as Set
+    }
+
+    def "SubtractingFileCollection supports absence of execution time value"() {
+        given:
+        def collection = new SubtractingFileCollection(left, right)
+
+        when:
+        def executionTimeValue = collection.calculateExecutionTimeValue()
+
+        then:
+        executionTimeValue.present == isPresent
+
+        where:
+        left                                               | right                                              | isPresent
+        new EmptyExecutionTimeValueFileCollection()        | fileCollectionFactory().fixed(new File("foo.txt")) | false
+        fileCollectionFactory().fixed(new File("foo.txt")) | new EmptyExecutionTimeValueFileCollection()        | false
+        new EmptyExecutionTimeValueFileCollection()        | new EmptyExecutionTimeValueFileCollection()        | false
+        fileCollectionFactory().fixed(new File("foo.txt")) | fileCollectionFactory().fixed(new File("bar.txt")) | true
+    }
+}
+