Fix and test jar processor caching.

src/main/java/net/fabricmc/loom/configuration/accesswidener/AccessWidenerEntry.java

@@ -42,5 +42,7 @@ public interface AccessWidenerEntry {
 	@Nullable
 	String mappingId();
 
+	String getSortKey();
+
 	void read(AccessWidenerVisitor visitor, LazyCloseable<TinyRemapper> remapper) throws IOException;
 }

src/main/java/net/fabricmc/loom/configuration/accesswidener/AccessWidenerJarProcessor.java

@@ -24,10 +24,13 @@
 
 package net.fabricmc.loom.configuration.accesswidener;
 
+import java.io.FileNotFoundException;
 import java.io.IOException;
+import java.io.UncheckedIOException;
+import java.nio.file.Files;
 import java.nio.file.Path;
 import java.util.ArrayList;
-import java.util.Collections;
+import java.util.Comparator;
 import java.util.List;
 
 import javax.inject.Inject;
@@ -62,8 +65,14 @@ public class AccessWidenerJarProcessor implements MinecraftJarProcessor<AccessWi
 		List<AccessWidenerEntry> accessWideners = new ArrayList<>();
 
 		if (localAccessWidenerProperty.isPresent()) {
+			Path path = localAccessWidenerProperty.get().getAsFile().toPath();
+
+			if (Files.notExists(path)) {
+				throw new UncheckedIOException(new FileNotFoundException("Could not find access widener file at {%s}".formatted(path)));
+			}
+
 			// Add the access widener specified in the extension
-			accessWideners.add(new LocalAccessWidenerEntry(localAccessWidenerProperty.get().getAsFile().toPath()));
+			accessWideners.add(LocalAccessWidenerEntry.create(path));
 		}
 
 		/* Uncomment to read all access wideners from local mods.
@@ -84,7 +93,7 @@ public class AccessWidenerJarProcessor implements MinecraftJarProcessor<AccessWi
 			return null;
 		}
 
-		return new Spec(Collections.unmodifiableList(accessWideners));
+		return new Spec(accessWideners.stream().sorted(Comparator.comparing(AccessWidenerEntry::getSortKey)).toList());
 	}
 
 	@Override

src/main/java/net/fabricmc/loom/configuration/accesswidener/LocalAccessWidenerEntry.java

@@ -25,6 +25,7 @@
 package net.fabricmc.loom.configuration.accesswidener;
 
 import java.io.IOException;
+import java.io.UncheckedIOException;
 import java.nio.file.Files;
 import java.nio.file.Path;
 
@@ -32,11 +33,20 @@ import org.jetbrains.annotations.Nullable;
 
 import net.fabricmc.accesswidener.AccessWidenerReader;
 import net.fabricmc.accesswidener.AccessWidenerVisitor;
+import net.fabricmc.loom.util.Checksum;
 import net.fabricmc.loom.util.LazyCloseable;
 import net.fabricmc.loom.util.fmj.ModEnvironment;
 import net.fabricmc.tinyremapper.TinyRemapper;
 
-public record LocalAccessWidenerEntry(Path path) implements AccessWidenerEntry {
+public record LocalAccessWidenerEntry(Path path, String hash) implements AccessWidenerEntry {
+	public static LocalAccessWidenerEntry create(Path path) {
+		try {
+			return new LocalAccessWidenerEntry(path, Checksum.sha1Hex(path));
+		} catch (IOException e) {
+			throw new UncheckedIOException("Failed to create LocalAccessWidenerEntry", e);
+		}
+	}
+
 	@Override
 	public void read(AccessWidenerVisitor visitor, LazyCloseable<TinyRemapper> remapper) throws IOException {
 		var reader = new AccessWidenerReader(visitor);
@@ -52,4 +62,14 @@ public record LocalAccessWidenerEntry(Path path) implements AccessWidenerEntry {
 	public @Nullable String mappingId() {
 		return null;
 	}
+
+	@Override
+	public String getSortKey() {
+		return "local";
+	}
+
+	@Override
+	public int hashCode() {
+		return hash.hashCode();
+	}
 }

src/main/java/net/fabricmc/loom/configuration/accesswidener/ModAccessWidenerEntry.java

@@ -61,6 +61,11 @@ public record ModAccessWidenerEntry(FabricModJson mod, String path, ModEnvironme
 		return transitiveOnly ? mod.getId() : null;
 	}
 
+	@Override
+	public String getSortKey() {
+		return mod.getId() + ":" + path;
+	}
+
 	@Override
 	public void read(AccessWidenerVisitor visitor, LazyCloseable<TinyRemapper> remapper) throws IOException {
 		if (transitiveOnly) {

src/main/java/net/fabricmc/loom/configuration/processors/MinecraftJarProcessorManager.java

@@ -34,10 +34,13 @@ import java.util.Collections;
 import java.util.Comparator;
 import java.util.List;
 import java.util.Objects;
+import java.util.StringJoiner;
 import java.util.stream.Collectors;
 
 import org.gradle.api.Project;
 import org.jetbrains.annotations.Nullable;
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
 
 import net.fabricmc.loom.LoomGradleExtension;
 import net.fabricmc.loom.api.processor.MappingProcessorContext;
@@ -49,6 +52,7 @@ import net.fabricmc.mappingio.tree.MemoryMappingTree;
 
 public final class MinecraftJarProcessorManager {
 	private static final String CACHE_VALUE_FILE_PATH = "META-INF/Loom-Jar-Processor-Cache";
+	private static final Logger LOGGER = LoggerFactory.getLogger(MinecraftJarProcessorManager.class);
 
 	private final List<ProcessorEntry<?>> jarProcessors;
 
@@ -73,14 +77,17 @@ public final class MinecraftJarProcessorManager {
 		List<ProcessorEntry<?>> entries = new ArrayList<>();
 
 		for (MinecraftJarProcessor<?> processor : processors) {
+			LOGGER.debug("Building processor spec for {}", processor.getName());
 			MinecraftJarProcessor.Spec spec = processor.buildSpec(context);
 
 			if (spec != null) {
+				LOGGER.debug("Adding processor entry for {}", processor.getName());
 				entries.add(new ProcessorEntry<>(processor, spec));
 			}
 		}
 
 		if (entries.isEmpty()) {
+			LOGGER.debug("No processor entries");
 			return null;
 		}
 
@@ -94,10 +101,23 @@ public final class MinecraftJarProcessorManager {
 				.collect(Collectors.joining("::"));
 	}
 
+	private String getDebugString() {
+		final StringJoiner sj = new StringJoiner("\n");
+
+		for (ProcessorEntry<?> jarProcessor : jarProcessors) {
+			sj.add(jarProcessor.name() + ":");
+			sj.add("\tHash: " + jarProcessor.hashCode());
+			sj.add("\tStr: " + jarProcessor.toString());
+		}
+
+		return sj.toString();
+	}
+
 	public boolean requiresProcessingJar(Path jar) {
 		Objects.requireNonNull(jar);
 
 		if (Files.notExists(jar)) {
+			LOGGER.debug("{} does not exist, generating", jar);
 			return true;
 		}
 
@@ -110,11 +130,23 @@ public final class MinecraftJarProcessorManager {
 		}
 
 		if (existingCache == null) {
+			LOGGER.info("{} does not contain a processor cache value, regenerating", jar);
 			return true;
 		}
 
 		final String existingCacheValue = new String(existingCache, StandardCharsets.UTF_8);
-		return !existingCacheValue.equals(getCacheValue());
+		final String expectedCacheValue = getCacheValue();
+		final boolean matches = existingCacheValue.equals(expectedCacheValue);
+
+		if (!matches) {
+			LOGGER.info("{} has an invalid cache, got {} expected {}", jar, existingCacheValue, expectedCacheValue);
+
+			if (LOGGER.isInfoEnabled()) {
+				LOGGER.info("Expected state: {}", getDebugString());
+			}
+		}
+
+		return !matches;
 	}
 
 	public void processJar(Path jar, ProcessorContext context) throws IOException {

src/main/java/net/fabricmc/loom/util/Checksum.java

@@ -62,7 +62,7 @@ public class Checksum {
 			HashCode hash = Files.asByteSource(file).hash(Hashing.sha256());
 			return hash.asBytes();
 		} catch (IOException e) {
-			throw new RuntimeException("Failed to get file hash");
+			throw new UncheckedIOException("Failed to get file hash", e);
 		}
 	}
 

src/main/java/net/fabricmc/loom/util/fmj/FabricModJson.java

@@ -33,8 +33,9 @@ import java.util.Objects;
 import com.google.gson.JsonElement;
 import com.google.gson.JsonObject;
 import org.jetbrains.annotations.Nullable;
+import org.jetbrains.annotations.VisibleForTesting;
 
-public abstract sealed class FabricModJson permits FabricModJsonV0, FabricModJsonV1, FabricModJsonV2 {
+public abstract sealed class FabricModJson permits FabricModJsonV0, FabricModJsonV1, FabricModJsonV2, FabricModJson.Mockable {
 	protected final JsonObject jsonObject;
 	private final FabricModJsonSource source;
 
@@ -59,4 +60,22 @@ public abstract sealed class FabricModJson permits FabricModJsonV0, FabricModJso
 	public final FabricModJsonSource getSource() {
 		return source;
 	}
+
+	@Override
+	public final String toString() {
+		return getClass().getName() + "[id=%s, version=%s, classTweakers=%s]".formatted(getId(), getVersion(), getClassTweakers());
+	}
+
+	@Override
+	public final int hashCode() {
+		return Objects.hash(getId(), getVersion());
+	}
+
+	@VisibleForTesting
+	public abstract non-sealed class Mockable extends FabricModJson {
+		private Mockable() {
+			super(null, null);
+			throw new AssertionError();
+		}
+	}
 }

src/main/java/net/fabricmc/loom/util/fmj/ModEnvironment.java

@@ -24,17 +24,21 @@
 
 package net.fabricmc.loom.util.fmj;
 
-public enum ModEnvironment {
-	UNIVERSAL(true, true),
-	CLIENT(true, false),
-	SERVER(false, true);
+import java.util.Objects;
+
+public final class ModEnvironment {
+	public static final ModEnvironment UNIVERSAL = new ModEnvironment(true, true, "universal");
+	public static final ModEnvironment CLIENT = new ModEnvironment(true, false, "client");
+	public static final ModEnvironment SERVER = new ModEnvironment(false, true, "server");
 
 	private final boolean client;
 	private final boolean server;
+	private final String name;
 
-	ModEnvironment(boolean client, boolean server) {
+	private ModEnvironment(boolean client, boolean server, String name) {
 		this.client = client;
 		this.server = server;
+		this.name = name;
 	}
 
 	public boolean isClient() {
@@ -44,4 +48,17 @@ public enum ModEnvironment {
 	public boolean isServer() {
 		return server;
 	}
+
+	@Override
+	public boolean equals(Object o) {
+		if (this == o) return true;
+		if (o == null || getClass() != o.getClass()) return false;
+		ModEnvironment that = (ModEnvironment) o;
+		return name.equals(that.name);
+	}
+
+	@Override
+	public int hashCode() {
+		return Objects.hash(name);
+	}
 }

src/test/groovy/net/fabricmc/loom/test/unit/ArtifactMetadataTest.groovy

@@ -26,16 +26,12 @@ package net.fabricmc.loom.test.unit
 
 import net.fabricmc.loom.configuration.mods.ArtifactMetadata
 import net.fabricmc.loom.configuration.mods.ArtifactRef
-import net.fabricmc.loom.util.FileSystemUtil
 import spock.lang.Specification
 
-import java.nio.charset.StandardCharsets
-import java.nio.file.Files
 import java.nio.file.Path
-import java.util.jar.Attributes
-import java.util.jar.Manifest
 
 import static net.fabricmc.loom.configuration.mods.ArtifactMetadata.RemapRequirements.*
+import static net.fabricmc.loom.test.util.ZipTestUtils.*
 
 class ArtifactMetadataTest extends Specification {
 	def "is fabric mod"() {
@@ -111,30 +107,4 @@ class ArtifactMetadataTest extends Specification {
 	private static ArtifactRef createArtifact(Path zip) {
 		return new ArtifactRef.FileArtifactRef(zip, "net.fabric", "loom-test", "1.0")
 	}
-
-	private static Path createZip(Map<String, String> entries) {
-		def file = Files.createTempFile("loom-test", ".zip")
-		Files.delete(file)
-
-		FileSystemUtil.getJarFileSystem(file, true).withCloseable { zip ->
-			entries.forEach { path, value ->
-				def fsPath = zip.getPath(path)
-				def fsPathParent = fsPath.getParent()
-				if (fsPathParent != null) Files.createDirectories(fsPathParent)
-				Files.writeString(fsPath, value, StandardCharsets.UTF_8)
-			}
-		}
-
-		return file
-	}
-
-	private String manifest(String key, String value) {
-		def manifest = new Manifest()
-		manifest.getMainAttributes().put(Attributes.Name.MANIFEST_VERSION, "1.0")
-		manifest.getMainAttributes().putValue(key, value)
-
-		def out = new ByteArrayOutputStream()
-		manifest.write(out)
-		return out.toString(StandardCharsets.UTF_8)
-	}
 }

src/test/groovy/net/fabricmc/loom/test/unit/fmj/FabricModJsonV0Test.groovy

@@ -101,4 +101,13 @@ class FabricModJsonV0Test extends Specification {
 		then:
 			fmj.getClassTweakers() == [:]
 	}
+
+	def "hash code"() {
+		given:
+			def mockSource = Mock(FabricModJsonSource)
+		when:
+			def fmj = FabricModJsonFactory.create(JSON_OBJECT, mockSource)
+		then:
+			fmj.hashCode() == 930565976
+	}
 }

src/test/groovy/net/fabricmc/loom/test/unit/fmj/FabricModJsonV1Test.groovy

@@ -107,4 +107,13 @@ class FabricModJsonV1Test extends Specification {
 		then:
 			fmj.getClassTweakers() == ["modid.accesswidener": ModEnvironment.UNIVERSAL]
 	}
+
+	def "hash code"() {
+		given:
+			def mockSource = Mock(FabricModJsonSource)
+		when:
+			def fmj = FabricModJsonFactory.create(JSON_OBJECT, mockSource)
+		then:
+			fmj.hashCode() == 930565977
+	}
 }

src/test/groovy/net/fabricmc/loom/test/unit/fmj/FabricModJsonV2Test.groovy

@@ -125,4 +125,13 @@ class FabricModJsonV2Test extends Specification {
 				"universal.ct": ModEnvironment.UNIVERSAL
 			]
 	}
+
+	def "hash code"() {
+		given:
+			def mockSource = Mock(FabricModJsonSource)
+		when:
+			def fmj = FabricModJsonFactory.create(JSON_OBJECT, mockSource)
+		then:
+			fmj.hashCode() == 930565978
+	}
 }

src/test/groovy/net/fabricmc/loom/test/unit/processor/AccessWidenerJarProcessorTest.groovy

@@ -0,0 +1,92 @@
+/*
+ * This file is part of fabric-loom, licensed under the MIT License (MIT).
+ *
+ * Copyright (c) 2023 FabricMC
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in all
+ * copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+ * SOFTWARE.
+ */
+
+package net.fabricmc.loom.test.unit.processor
+
+import net.fabricmc.loom.api.processor.SpecContext
+import net.fabricmc.loom.configuration.accesswidener.AccessWidenerJarProcessor
+import net.fabricmc.loom.test.util.GradleTestUtil
+import net.fabricmc.loom.util.fmj.FabricModJson
+import net.fabricmc.loom.util.fmj.ModEnvironment
+import spock.lang.Specification
+
+class AccessWidenerJarProcessorTest extends Specification {
+    def "Local AW"() {
+        given:
+            def specContext = Mock(SpecContext)
+            def file = new File("src/test/resources/accesswidener/AccessWidenerJarProcessorTest.accesswidener")
+            def localAccessWidenerProperty = GradleTestUtil.mockRegularFileProperty(file)
+
+            def processor = new AccessWidenerJarProcessor("AccessWidener", true, localAccessWidenerProperty)
+            specContext.modDependencies() >> []
+
+        when:
+            def spec = processor.buildSpec(specContext)
+
+        then:
+            spec != null
+            spec.hashCode() == 1205905061
+    }
+
+    def "Dep AW"() {
+        given:
+            def specContext = Mock(SpecContext)
+
+            def mod1 = Mock(FabricModJson.Mockable)
+            mod1.getClassTweakers() >> ["test.accesswidener": ModEnvironment.UNIVERSAL]
+            mod1.getId() >> "modid1"
+
+            def mod2 = Mock(FabricModJson.Mockable)
+            mod2.getClassTweakers() >> ["test2.accesswidener": ModEnvironment.UNIVERSAL]
+            mod2.getId() >> "modid2"
+
+            specContext.modDependencies() >> [
+                mod1,
+                mod2
+            ].shuffled()
+
+        def processor = new AccessWidenerJarProcessor("AccessWidener", true, GradleTestUtil.mockRegularFileProperty(null))
+
+        when:
+            def spec = processor.buildSpec(specContext)
+
+        then:
+            spec != null
+            spec.hashCode() == 1534839952
+    }
+
+    def "No AWs"() {
+        given:
+            def specContext = Mock(SpecContext)
+            specContext.modDependencies() >> []
+
+            def processor = new AccessWidenerJarProcessor("AccessWidener", true, GradleTestUtil.mockRegularFileProperty(null))
+
+        when:
+            def spec = processor.buildSpec(specContext)
+
+        then:
+            spec == null
+    }
+}

src/test/groovy/net/fabricmc/loom/test/unit/processor/MinecraftJarProcessorManagerTest.groovy

@@ -0,0 +1,70 @@
+/*
+ * This file is part of fabric-loom, licensed under the MIT License (MIT).
+ *
+ * Copyright (c) 2023 FabricMC
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in all
+ * copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+ * SOFTWARE.
+ */
+
+package net.fabricmc.loom.test.unit.processor
+
+import net.fabricmc.loom.api.processor.ProcessorContext
+import net.fabricmc.loom.api.processor.SpecContext
+import net.fabricmc.loom.configuration.processors.MinecraftJarProcessorManager
+import net.fabricmc.loom.test.util.processor.TestMinecraftJarProcessor
+import spock.lang.Specification
+
+import static net.fabricmc.loom.test.util.ZipTestUtils.createZip
+
+class MinecraftJarProcessorManagerTest extends Specification {
+    def "Does not require re-processing"() {
+        given:
+            def specContext = Mock(SpecContext)
+            def processorContext = Mock(ProcessorContext)
+
+            def processor1 = new TestMinecraftJarProcessor(input: "Test1")
+            def processor2 = new TestMinecraftJarProcessor(input: "Test2")
+            def manager = MinecraftJarProcessorManager.create([processor1, processor2], specContext)
+
+        when:
+            def jar = createZip(["fabric.mod.json": "{}"])
+            manager.processJar(jar, processorContext)
+
+        then:
+            !manager.requiresProcessingJar(jar)
+    }
+
+    def "Requires re-processing"() {
+        given:
+            def specContext = Mock(SpecContext)
+            def processorContext = Mock(ProcessorContext)
+
+            def processor1 = new TestMinecraftJarProcessor(input: "Test1")
+            def processor2 = new TestMinecraftJarProcessor(input: "Test2")
+            def manager1 = MinecraftJarProcessorManager.create([processor1], specContext)
+            def manager2 = MinecraftJarProcessorManager.create([processor1, processor2], specContext)
+
+        when:
+            def jar = createZip(["fabric.mod.json": "{}"])
+            manager1.processJar(jar, processorContext)
+
+        then:
+            manager2.requiresProcessingJar(jar)
+    }
+}

src/test/groovy/net/fabricmc/loom/test/unit/processor/ModAccessWidenerEntryTest.groovy

@@ -0,0 +1,50 @@
+/*
+ * This file is part of fabric-loom, licensed under the MIT License (MIT).
+ *
+ * Copyright (c) 2023 FabricMC
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in all
+ * copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+ * SOFTWARE.
+ */
+
+package net.fabricmc.loom.test.unit.processor
+
+import net.fabricmc.loom.configuration.accesswidener.ModAccessWidenerEntry
+import net.fabricmc.loom.util.fmj.FabricModJson
+import net.fabricmc.loom.util.fmj.ModEnvironment
+import spock.lang.Specification
+
+class ModAccessWidenerEntryTest extends Specification {
+    def "read local mod"() {
+        given:
+            def mod = Mock(FabricModJson.Mockable)
+            mod.getClassTweakers() >> ["test.accesswidener": ModEnvironment.UNIVERSAL]
+            mod.hashCode() >> 0
+
+        when:
+            def entries = ModAccessWidenerEntry.readAll(mod, true)
+        then:
+            entries.size() == 1
+            def entry = entries[0]
+
+            entry.path() == "test.accesswidener"
+            entry.environment() == ModEnvironment.UNIVERSAL
+            entry.transitiveOnly()
+            entry.hashCode() == -1218981396
+    }
+}

src/test/groovy/net/fabricmc/loom/test/util/GradleTestUtil.groovy

@@ -26,6 +26,8 @@ package net.fabricmc.loom.test.util
 
 import net.fabricmc.loom.LoomGradleExtension
 import org.gradle.api.Project
+import org.gradle.api.file.RegularFile
+import org.gradle.api.file.RegularFileProperty
 import org.gradle.api.file.SourceDirectorySet
 import org.gradle.api.internal.tasks.DefaultSourceSet
 import org.gradle.api.model.ObjectFactory
@@ -33,6 +35,7 @@ import org.gradle.api.plugins.ExtensionContainer
 import org.gradle.api.provider.Property
 import org.gradle.api.tasks.SourceSet
 import org.gradle.api.tasks.util.PatternFilterable
+import org.jetbrains.annotations.Nullable
 
 import static org.mockito.ArgumentMatchers.any
 import static org.mockito.Mockito.mock
@@ -90,4 +93,25 @@ class GradleTestUtil {
 		def mock = mock(PatternFilterable.class)
 		return mock
 	}
+
+	static RegularFile mockRegularFile(File file) {
+		def mock = mock(RegularFile.class)
+		when(mock.getAsFile()).thenReturn(file)
+		return mock
+	}
+
+	static RegularFileProperty mockRegularFileProperty(@Nullable File file) {
+		if (file == null) {
+			def mock = mock(RegularFileProperty.class)
+			when(mock.isPresent()).thenReturn(false)
+			return mock
+		}
+
+		def regularFile = mockRegularFile(file.getAbsoluteFile())
+
+		def mock = mock(RegularFileProperty.class)
+		when(mock.get()).thenReturn(regularFile)
+		when(mock.isPresent()).thenReturn(true)
+		return mock
+	}
 }

src/test/groovy/net/fabricmc/loom/test/util/ZipTestUtils.groovy

@@ -0,0 +1,61 @@
+/*
+ * This file is part of fabric-loom, licensed under the MIT License (MIT).
+ *
+ * Copyright (c) 2023 FabricMC
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in all
+ * copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+ * SOFTWARE.
+ */
+
+package net.fabricmc.loom.test.util
+
+import net.fabricmc.loom.util.FileSystemUtil
+
+import java.nio.charset.StandardCharsets
+import java.nio.file.Files
+import java.nio.file.Path
+import java.util.jar.Attributes
+import java.util.jar.Manifest
+
+class ZipTestUtils {
+    static Path createZip(Map<String, String> entries) {
+        def file = Files.createTempFile("loom-test", ".zip")
+        Files.delete(file)
+
+        FileSystemUtil.getJarFileSystem(file, true).withCloseable { zip ->
+            entries.forEach { path, value ->
+                def fsPath = zip.getPath(path)
+                def fsPathParent = fsPath.getParent()
+                if (fsPathParent != null) Files.createDirectories(fsPathParent)
+                Files.writeString(fsPath, value, StandardCharsets.UTF_8)
+            }
+        }
+
+        return file
+    }
+
+    static String manifest(String key, String value) {
+        def manifest = new Manifest()
+        manifest.getMainAttributes().put(Attributes.Name.MANIFEST_VERSION, "1.0")
+        manifest.getMainAttributes().putValue(key, value)
+
+        def out = new ByteArrayOutputStream()
+        manifest.write(out)
+        return out.toString(StandardCharsets.UTF_8)
+    }
+}

src/test/groovy/net/fabricmc/loom/test/util/processor/TestMinecraftJarProcessor.groovy

@@ -0,0 +1,57 @@
+/*
+ * This file is part of fabric-loom, licensed under the MIT License (MIT).
+ *
+ * Copyright (c) 2023 FabricMC
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in all
+ * copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+ * SOFTWARE.
+ */
+
+package net.fabricmc.loom.test.util.processor
+
+import groovy.transform.Immutable
+import net.fabricmc.loom.api.processor.MinecraftJarProcessor
+import net.fabricmc.loom.api.processor.ProcessorContext
+import net.fabricmc.loom.api.processor.SpecContext
+
+import java.nio.file.Path
+
+@Immutable
+class TestMinecraftJarProcessor implements MinecraftJarProcessor<Spec> {
+    String input
+
+    final String name = "TestProcessor"
+
+    @Override
+    Spec buildSpec(SpecContext context) {
+        if (input == null) {
+            return null
+        }
+
+        return new Spec(input)
+    }
+
+    @Immutable
+    class Spec implements MinecraftJarProcessor.Spec {
+        String input
+    }
+
+    @Override
+    void processJar(Path jar, Spec spec, ProcessorContext context) throws IOException {
+    }
+}

src/test/resources/accesswidener/AccessWidenerJarProcessorTest.accesswidener

@@ -0,0 +1,3 @@
+accessWidener	v2	named
+
+transitive-accessible method net/minecraft/recipe/BrewingRecipeRegistry registerPotionType (Lnet/minecraft/item/Item;)V