Deduplicate sign task inputs

Multiple inputs can be defined that point at the same file.

subprojects/signing/src/integTest/groovy/org/gradle/plugins/signing/SigningConfigurationsIntegrationSpec.groovy

@@ -79,4 +79,30 @@ class SigningConfigurationsIntegrationSpec extends SigningIntegrationSpec {
         and:
         file("build", "libs", "sign-1.0.jar.asc").text
     }
+
+    def "duplicated inputs are handled"() {
+        given:
+        buildFile << """
+            signing {
+                ${signingConfiguration()}
+                sign configurations.archives
+            }
+
+            ${keyInfo.addAsPropertiesScript()}
+
+            artifacts {
+                // depend directly on 'jar' task in addition to dependency through 'archives'
+                archives jar  
+            }
+        """
+
+        when:
+        run "buildSignatures"
+
+        then:
+        executedAndNotSkipped ":signArchives"
+
+        and:
+        file("build", "libs", "sign-1.0.jar.asc").text
+    }
 }

subprojects/signing/src/main/java/org/gradle/plugins/signing/Sign.java

@@ -84,7 +84,8 @@ public Iterable<File> getInputFiles() {
     public Map<String, File> getOutputFiles() {
         SingleMessageLogger.nagUserOfDiscontinuedMethod("Sign.getOutputFiles()",
             "Please use Sign.getSignatures() and Signature.getFile() instead.");
-        return signaturesForExsitingFiles().stream().collect(toMap(Signature::toKey, Signature::getFile));
+        // will be removed in 6.0
+        return sanitizedSignatures().entrySet().stream().collect(toMap(Map.Entry::getKey, entry -> entry.getValue().getFile()));
     }
 
     /**
@@ -224,7 +225,7 @@ public void generate() {
             throw new InvalidUserDataException("Cannot perform signing task \'" + getPath() + "\' because it has no configured signatory");
         }
 
-        for (Signature signature : signaturesForExsitingFiles()) {
+        for (Signature signature : sanitizedSignatures().values()) {
             signature.generate();
         }
     }
@@ -244,11 +245,14 @@ public DomainObjectSet<Signature> getSignatures() {
     @Nested
     @Incubating
     public Map<String, Signature> getSignaturesByKey() {
-        return signaturesForExsitingFiles().stream().collect(toMap(Signature::toKey, identity()));
+        return sanitizedSignatures();
     }
 
-    private DomainObjectSet<Signature> signaturesForExsitingFiles() {
-        return signatures.matching(signature -> signature.getToSign().exists());
+    /**
+     * Returns signatures mapped by their key with duplicated and non-existing inputs removed.
+     */
+    private Map<String, Signature> sanitizedSignatures() {
+        return signatures.matching(signature -> signature.getToSign().exists()).stream().collect(toMap(Signature::toKey, identity(), (signature, duplicate) -> signature));
     }
 
     /**
@@ -259,10 +263,11 @@ private DomainObjectSet<Signature> signaturesForExsitingFiles() {
      */
     @Internal
     public Signature getSingleSignature() {
-        if (signatures.size() == 1) {
-            return signatures.iterator().next();
+        Map<String, Signature> sanitizedSignatures = sanitizedSignatures();
+        if (sanitizedSignatures.size() == 1) {
+            return sanitizedSignatures.values().iterator().next();
         }
-        throw new IllegalStateException("Expected %s to contain exactly one signature, however, it contains " + signatures.size() + " signatures.");
+        throw new IllegalStateException("Expected %s to contain exactly one signature, however, it contains " + sanitizedSignatures.size() + " signatures.");
     }
 
     @Inject

subprojects/signing/src/test/groovy/org/gradle/plugins/signing/SigningTasksSpec.groovy

@@ -24,6 +24,7 @@ class SigningTasksSpec extends SigningProjectSpec {
     def "sign jar with defaults"() {
         given:
         useJavadocAndSourceJars()
+        createJarTaskOutputFile('jar', 'sourcesJar', 'javadocJar')
 
         when:
         signing {
@@ -68,15 +69,13 @@ class SigningTasksSpec extends SigningProjectSpec {
         useJavadocAndSourceJars()
         applyPlugin()
         addSigningProperties()
+        createJarTaskOutputFile('jar')
 
         when:
         Sign signTask = signing.sign(jar).first()
 
         then:
-        def jarFile = jar.outputs.files.singleFile
-        File libsDir = jarFile.parentFile
-        libsDir.mkdirs()
-        jarFile.createNewFile()
+        def libsDir = jar.outputs.files.singleFile.parentFile
         signTask.outputFiles == ["test.jar.asc:jar.asc:asc:": new File(libsDir, "test.jar.asc")]
         signTask.signaturesByKey == ["test.jar.asc:jar.asc:asc:": signTask.singleSignature]
     }
@@ -96,6 +95,23 @@ class SigningTasksSpec extends SigningProjectSpec {
         signTask.signaturesByKey == [:]
     }
 
+    def "files to sign are de-duplicated"() {
+        given:
+        useJavadocAndSourceJars()
+        applyPlugin()
+        addSigningProperties()
+        createJarTaskOutputFile('jar')
+
+        when:
+        Sign signTask = signing.sign(jar).first()
+        signTask.sign('', jar.outputs.files.singleFile) // add jar task output again, this time directly as File
+
+        then:
+        signTask.signatures.size() == 2
+        noExceptionThrown()
+        signTask.signaturesByKey == ["test.jar.asc:jar.asc:asc:": signTask.singleSignature]
+    }
+
     def "sign task has description"() {
         given:
         useJavadocAndSourceJars()
@@ -109,4 +125,14 @@ class SigningTasksSpec extends SigningProjectSpec {
         signJar.description == "Signs the archive produced by the 'jar' task."
         signSourcesJar.description == "Signs the archive produced by the 'sourcesJar' task."
     }
+
+    private createJarTaskOutputFile(String... tasksToSimulate) {
+        for (def task : tasksToSimulate) {
+            def jarFile = tasks.getByName(task).outputs.files.singleFile
+            File libsDir = jarFile.parentFile
+            libsDir.mkdirs()
+            jarFile.createNewFile()
+        }
+
+    }
 }