When starting a named transaction then GitDbTransaction is returned

src/main/java/net/kemitix/gitdb/GitDBBranch.java

@@ -70,4 +70,26 @@ public interface GitDBBranch {
      * @throws IOException error reading version
      */
     Optional<Version> getFormatVersion() throws IOException;
+
+    /**
+     * Begins a new anonymous transaction.
+     *
+     * @return a new Transaction
+     */
+    GitDBTransaction transaction() throws IOException;
+
+    /**
+     * Begins a new named transaction.
+     *
+     * @param name the transaction name
+     * @return a new Transaction
+     */
+    GitDBTransaction transaction(String name) throws IOException;
+
+    /**
+     * Gets the name of the branch.
+     *
+     * @return the branch name
+     */
+    String name();
 }

src/main/java/net/kemitix/gitdb/GitDBTransaction.java

@@ -0,0 +1,37 @@
+/*
+  The MIT License (MIT)
+
+  Copyright (c) 2018 Paul Campbell
+
+  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.kemitix.gitdb;
+
+/**
+ * Represents a transaction (a git branch).
+ *
+ * @author Paul Campbell (pcampbell@kemitix.net)
+ */
+public interface GitDBTransaction extends GitDBBranch {
+
+    /**
+     * The name of the transaction.
+     *
+     * @return the transaction name
+     */
+    String name();
+}

src/main/java/net/kemitix/gitdb/impl/GitDBBranchImpl.java

@@ -25,12 +25,14 @@ import com.github.zafarkhaja.semver.Version;
 import lombok.AccessLevel;
 import lombok.RequiredArgsConstructor;
 import net.kemitix.gitdb.GitDBBranch;
+import net.kemitix.gitdb.GitDBTransaction;
 import org.eclipse.jgit.lib.ObjectId;
 import org.eclipse.jgit.lib.Ref;
 import org.eclipse.jgit.lib.Repository;
 
 import java.io.*;
 import java.util.Optional;
+import java.util.UUID;
 import java.util.function.Function;
 
 /**
@@ -46,6 +48,7 @@ class GitDBBranchImpl implements GitDBBranch {
     private final GitDBRepo gitDBRepo;
     private final String userName;
     private final String userEmailAddress;
+    private final String name;
 
     private static GitDBBranch select(
             final Ref branchRef,
@@ -53,7 +56,7 @@ class GitDBBranchImpl implements GitDBBranch {
             final String userName,
             final String userEmailAddress
     ) {
-        return new GitDBBranchImpl(branchRef, gitDBRepo, userName, userEmailAddress);
+        return new GitDBBranchImpl(branchRef, gitDBRepo, userName, userEmailAddress, branchRef.getName());
     }
 
     /**
@@ -106,6 +109,23 @@ class GitDBBranchImpl implements GitDBBranch {
                 .map(Version::valueOf);
     }
 
+    @Override
+    public GitDBTransaction transaction(String name) throws IOException {
+        final Ref ref = gitDBRepo.createBranch(branchRef, UUID.randomUUID().toString());
+        final GitDBBranch branch = new GitDBBranchImpl(ref, gitDBRepo, userName, userEmailAddress, name);
+        return new UnnamedTransaction(this, branch);
+    }
+
+    @Override
+    public GitDBTransaction transaction() throws IOException {
+        return transaction(UUID.randomUUID().toString());
+    }
+
+    @Override
+    public String name() {
+        return name;
+    }
+
     private String commitMessageForAdd(final String key, final String value) {
         return String.format("Add key [%s] = [%s]", key, value);
     }

src/main/java/net/kemitix/gitdb/impl/GitDBRepo.java

@@ -227,4 +227,8 @@ class GitDBRepo {
     Optional<ObjectId> removeKey(final Ref branchRef, final String key) throws IOException {
         return keyRemover.remove(branchRef, key);
     }
+
+    Ref createBranch(final Ref branchRef, final String name) throws IOException {
+        return repository.getRefDatabase().newUpdate(name, false).getRef();
+    }
 }

src/main/java/net/kemitix/gitdb/impl/UnnamedTransaction.java

@@ -0,0 +1,79 @@
+/*
+  The MIT License (MIT)
+
+  Copyright (c) 2018 Paul Campbell
+
+  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.kemitix.gitdb.impl;
+
+import com.github.zafarkhaja.semver.Version;
+import net.kemitix.gitdb.GitDBBranch;
+import net.kemitix.gitdb.GitDBTransaction;
+
+import java.util.Optional;
+
+/**
+ * An anonymous transaction.
+ *
+ * @author Paul Campbell (pcampbell@kemitix.net)
+ */
+class UnnamedTransaction implements GitDBTransaction {
+
+    private final GitDBBranch base;
+    private final GitDBBranch branch;
+
+    UnnamedTransaction(final GitDBBranch base, final GitDBBranch branch) {
+        this.base = base;
+        this.branch = branch;
+    }
+
+    @Override
+    public Optional<String> get(String key) {
+        return Optional.empty();
+    }
+
+    @Override
+    public GitDBBranch put(String key, String value) {
+        return null;
+    }
+
+    @Override
+    public GitDBBranch remove(String key) {
+        return null;
+    }
+
+    @Override
+    public Optional<Version> getFormatVersion() {
+        return Optional.empty();
+    }
+
+    @Override
+    public GitDBTransaction transaction() {
+        return null;
+    }
+
+    @Override
+    public GitDBTransaction transaction(String name) {
+        return null;
+    }
+
+    @Override
+    public String name() {
+        return branch.name();
+    }
+}

src/test/java/net/kemitix/gitdb/test/GitDBTest.java

@@ -3,6 +3,7 @@ package net.kemitix.gitdb.test;
 import com.github.zafarkhaja.semver.Version;
 import net.kemitix.gitdb.GitDB;
 import net.kemitix.gitdb.GitDBBranch;
+import net.kemitix.gitdb.GitDBTransaction;
 import net.kemitix.gitdb.InvalidRepositoryException;
 import org.assertj.core.api.WithAssertions;
 import org.eclipse.jgit.api.Git;
@@ -310,6 +311,20 @@ class GitDBTest implements WithAssertions {
     }
 
     // When starting a named transaction then GitDbTransaction is returned
+    @Test
+    void startTransaction_thenReturnGitDBTransaction() throws IOException {
+        //given
+        final String key = stringSupplier.get();
+        final String value = stringSupplier.get();
+        final GitDBBranch gitDBBranch = gitDBBranchWithKeyValue(key, value);
+        final String name = stringSupplier.get();
+        //when
+        final GitDBTransaction transaction = gitDBBranch.transaction(name);
+        //then
+        assertThat(transaction).isNotNull();
+        assertThat(transaction.name()).isEqualTo(name);
+    }
+
     // When starting an anonymous transaction then a GitDbTransaction is returned
 
     // Given a GitDbTransaction handle (i.e. a new branch)