Throw error if branch name of new pull request conflicts with an existing branch

extension/tasks/dependabotV2/index.ts

@@ -48,7 +48,8 @@ async function run() {
       : null;
 
     // Fetch the active pull requests created by the author user
-    const prAuthorActivePullRequests = await prAuthorClient.getActivePullRequestProperties(
+    const existingBranchNames = await prAuthorClient.getBranchNames(taskInputs.project, taskInputs.repository);
+    const existingPullRequests = await prAuthorClient.getActivePullRequestProperties(
       taskInputs.project,
       taskInputs.repository,
       await prAuthorClient.getUserId(),
@@ -57,7 +58,13 @@ async function run() {
     // Initialise the Dependabot updater
     dependabot = new DependabotCli(
       DependabotCli.CLI_IMAGE_LATEST, // TODO: Add config for this?
-      new DependabotOutputProcessor(taskInputs, prAuthorClient, prApproverClient, prAuthorActivePullRequests),
+      new DependabotOutputProcessor(
+        taskInputs,
+        prAuthorClient,
+        prApproverClient,
+        existingPullRequests,
+        existingBranchNames,
+      ),
       taskInputs.debug,
     );
 
@@ -88,20 +95,26 @@ async function run() {
     // Loop through the [targeted] update blocks in dependabot.yaml and perform updates
     for (const update of updates) {
       const updateId = updates.indexOf(update).toString();
+      const packageEcosystem = update['package-ecosystem'];
 
       // Parse the last dependency list snapshot (if any) from the project properties.
       // This is required when doing a security-only update as dependabot requires the list of vulnerable dependencies to be updated.
       // Automatic discovery of vulnerable dependencies during a security-only update is not currently supported by dependabot-updater.
       const dependencyList = parseProjectDependencyListProperty(
         await prAuthorClient.getProjectProperties(taskInputs.projectId),
         taskInputs.repository,
-        update['package-ecosystem'],
+        packageEcosystem,
       );
 
       // Parse the Dependabot metadata for the existing pull requests that are related to this update
       // Dependabot will use this to determine if we need to create new pull requests or update/close existing ones
-      const existingPullRequests = parsePullRequestProperties(prAuthorActivePullRequests, update['package-ecosystem']);
-      const existingPullRequestDependencies = Object.entries(existingPullRequests).map(([id, deps]) => deps);
+      const existingPullRequestsForPackageEcosystem = parsePullRequestProperties(
+        existingPullRequests,
+        packageEcosystem,
+      );
+      const existingPullRequestDependenciesForPackageEcosystem = Object.entries(
+        existingPullRequestsForPackageEcosystem,
+      ).map(([id, deps]) => deps);
 
       // Run an update job for "all dependencies"; this will create new pull requests for dependencies that need updating
       failedTasks += handleUpdateOperationResults(
@@ -112,26 +125,26 @@ async function run() {
             update,
             dependabotConfig.registries,
             dependencyList?.['dependencies'],
-            existingPullRequestDependencies,
+            existingPullRequestDependenciesForPackageEcosystem,
           ),
           dependabotUpdaterOptions,
         ),
       );
 
       // If there are existing pull requests, run an update job for each one; this will resolve merge conflicts and close pull requests that are no longer needed
-      const numberOfPullRequestsToUpdate = Object.keys(existingPullRequests).length;
+      const numberOfPullRequestsToUpdate = Object.keys(existingPullRequestsForPackageEcosystem).length;
       if (numberOfPullRequestsToUpdate > 0) {
         if (!taskInputs.skipPullRequests) {
-          for (const pullRequestId in existingPullRequests) {
+          for (const pullRequestId in existingPullRequestsForPackageEcosystem) {
             failedTasks += handleUpdateOperationResults(
               await dependabot.update(
                 DependabotJobBuilder.newUpdatePullRequestJob(
                   taskInputs,
                   pullRequestId,
                   update,
                   dependabotConfig.registries,
-                  existingPullRequestDependencies,
-                  existingPullRequests[pullRequestId],
+                  existingPullRequestDependenciesForPackageEcosystem,
+                  existingPullRequestsForPackageEcosystem[pullRequestId],
                 ),
                 dependabotUpdaterOptions,
               ),

extension/tasks/dependabotV2/utils/azure-devops/AzureDevOpsWebApiClient.ts

@@ -97,6 +97,30 @@ export class AzureDevOpsWebApiClient {
     }
   }
 
+  /**
+   * Get the list of branch names for a repository.
+   * Requires scope "Code (Read)" (vso.code).
+   * @param project
+   * @param repository
+   * @returns
+   */
+  public async getBranchNames(project: string, repository: string): Promise<string[]> {
+    try {
+      const refs = await this.restApiGet(
+        `${this.organisationApiUrl}/${project}/_apis/git/repositories/${repository}/refs`,
+      );
+      if (!refs) {
+        throw new Error(`Repository '${project}/${repository}' not found`);
+      }
+
+      return refs.value?.map((r) => normalizeBranchName(r.name)) || [];
+    } catch (e) {
+      error(`Failed to list branch names for '${project}/${repository}': ${e}`);
+      console.debug(e); // Dump the error stack trace to help with debugging
+      return undefined;
+    }
+  }
+
   /**
    * Get the properties for all active pull request created by the supplied user.
    * Requires scope "Code (Read)" (vso.code).

extension/tasks/dependabotV2/utils/dependabot-cli/DependabotOutputProcessor.ts

@@ -16,6 +16,7 @@ export class DependabotOutputProcessor implements IDependabotUpdateOutputProcess
   private readonly prAuthorClient: AzureDevOpsWebApiClient;
   private readonly prApproverClient: AzureDevOpsWebApiClient;
   private readonly existingPullRequests: IPullRequestProperties[];
+  private readonly existingBranchNames: string[];
   private readonly taskInputs: ISharedVariables;
 
   // Custom properties used to store dependabot metadata in projects.
@@ -35,11 +36,13 @@ export class DependabotOutputProcessor implements IDependabotUpdateOutputProcess
     prAuthorClient: AzureDevOpsWebApiClient,
     prApproverClient: AzureDevOpsWebApiClient,
     existingPullRequests: IPullRequestProperties[],
+    existingBranchNames: string[],
   ) {
     this.taskInputs = taskInputs;
     this.prAuthorClient = prAuthorClient;
     this.prApproverClient = prApproverClient;
     this.existingPullRequests = existingPullRequests;
+    this.existingBranchNames = existingBranchNames;
   }
 
   /**
@@ -95,7 +98,6 @@ export class DependabotOutputProcessor implements IDependabotUpdateOutputProcess
           return true;
         }
 
-        // Create a new pull request
         const changedFiles = getPullRequestChangedFilesForOutputData(data);
         const dependencies = getPullRequestDependenciesPropertyValueForOutputData(data);
         const targetBranch =
@@ -108,6 +110,24 @@ export class DependabotOutputProcessor implements IDependabotUpdateOutputProcess
           dependencies['dependencies'] || dependencies,
           update.config['pull-request-branch-name']?.separator,
         );
+
+        // Check if the source branch already exists or conflicts with an existing branch
+        const existingBranch = this.existingBranchNames?.find((branch) => sourceBranch == branch) || [];
+        if (existingBranch.length) {
+          error(
+            `Unable to create pull request as source branch '${sourceBranch}' already exists; Delete the existing branch and try again.`,
+          );
+          return false;
+        }
+        const conflictingBranches = this.existingBranchNames?.filter((branch) => sourceBranch.startsWith(branch)) || [];
+        if (conflictingBranches.length) {
+          error(
+            `Unable to create pull request as source branch '${sourceBranch}' would conflict with existing branch(es) '${conflictingBranches.join(', ')}'; Delete the conflicting branch(es) and try again.`,
+          );
+          return false;
+        }
+
+        // Create a new pull request
         const newPullRequestId = await this.prAuthorClient.createPullRequest({
           project: project,
           repository: repository,