Add JSON output option to 'prepare-release' command

doc/nbgv-cli.md

@@ -121,6 +121,49 @@ The behaviour of the `prepare-release` command can be customized in
 | versionIncrement | `minor`              | Specifies which part of the version on the current branch is incremented when preparing a release. Allowed values are `major`, `minor` and `build`. |
 | firstUnstableTag | `alpha`              | Specified the unstable tag to use for the main branch.                                                                                              |
 
+### Customizing the `prepare-release` output format
+
+By default, the `prepare-release` command writes information about created and updated branches to the console as text.
+Alternatively the information can be written to the output as `json`.
+The output format to use can be set using the `--format` command line parameter.
+
+For example, running the follwoing command on `master`
+
+```
+nbgv prepare-release --format json
+```
+
+will generate output similar to this:
+
+```json
+{
+  "CurrentBranch": {
+    "Name": "master",
+    "Commit": "5a7487098ac1be1ceb4dbf72d862539cf0b0c27a",
+    "Version": "1.7-alpha"
+  },
+  "NewBranch": {
+    "Name": "v1.7",
+    "Commit": "b2f164675ffe891b66b601c00efc4343581fc8a5",
+    "Version": "1.7"
+  }
+}
+```
+
+The JSON object has to properties:
+
+- `CurrentBranch` provides information about the branch `prepare-release` was started on (typically `master`)
+- `NewBranch` provides information about the new branch created by the command.
+
+For each branch, the following proprties are provided:
+
+- `Name`: The name of the branch
+- `Commit`: The id of the latest commit on that branch
+- `Version`: The version configured in that branch's `version.json`
+
+**Note:** When the current branch is already the release branch for the current version, no new branch will be created.
+In that case, the `NewBranch` property will be `null`.
+
 ## Learn more
 
 There are several more sub-commands and switches to each to help you build and maintain your projects, find a commit that built a particular version later on, create tags, etc.

src/NerdBank.GitVersioning.Tests/ReleaseManagerTests.cs

@@ -3,6 +3,8 @@
 using System.Linq;
 using LibGit2Sharp;
 using Nerdbank.GitVersioning;
+using Newtonsoft.Json;
+using Newtonsoft.Json.Linq;
 using Xunit;
 using Xunit.Abstractions;
 
@@ -401,6 +403,156 @@ public void PrepareRelease_InvalidVersionIncrement()
         this.AssertError(() => new ReleaseManager().PrepareRelease(this.RepoPath), ReleasePreparationError.InvalidVersionIncrementSetting);
     }
 
+    [Fact]
+    public void PrepareRelease_TextOutput()
+    {
+        // create and configure repository
+        this.InitializeSourceControl();
+
+        // create version.json
+        var versionOptions = new VersionOptions() { Version = SemanticVersion.Parse("1.0") };
+        this.WriteVersionFile(versionOptions);
+
+        var stdout = new StringWriter();
+        var releaseManager = new ReleaseManager(stdout);
+        releaseManager.PrepareRelease(this.RepoPath);
+
+        // by default, text output mode should be used => trying to parse it as JSON should fail
+        Assert.ThrowsAny<JsonException>(() => JsonConvert.DeserializeObject(stdout.ToString()));
+    }
+
+    [Fact]
+    public void PrepareRelease_JsonOutput()
+    {
+        // create and configure repository
+        this.InitializeSourceControl();
+
+        // create version.json
+        var versionOptions = new VersionOptions()
+        {
+            Version = SemanticVersion.Parse("1.0"),
+            Release = new ReleaseOptions()
+            {
+                BranchName = "v{version}",
+                VersionIncrement = ReleaseVersionIncrement.Minor
+            }
+        };
+        this.WriteVersionFile(versionOptions);
+
+        var currentBranchName = this.Repo.Head.FriendlyName;
+        var releaseBranchName = "v1.0";
+
+        // run release preparation
+        var stdout = new StringWriter();
+        var releaseManager = new ReleaseManager(stdout);
+        releaseManager.PrepareRelease(this.RepoPath, outputMode: ReleaseManager.ReleaseManagerOutputMode.Json);
+
+
+        // Expected output:
+        // {
+        //     "CurrentBranch" : {
+        //         "Name" : "<NAME-OF-CURRENT-BRANCH>",
+        //         "Commit" : "<HEAD-COMMIT-OF-CURRENT-BRANCH>",
+        //         "Version" : "<UPDATED-VERSION-ON-CURRENT-BRANCH>",
+        //     },
+        //     "NewBranch" : {
+        //         "Name" : "<NAME-OF-CREATED-BRANCH>",
+        //         "Commit" : "<HEAD-COMMIT-OF-CREATED-BRANCH>",
+        //         "Version" : "<VERSION-ON-CREATED-BRANCH>",
+        //     }
+        // }
+
+        var jsonOutput = JObject.Parse(stdout.ToString());
+
+        // check "CurrentBranch" output
+        {
+            var expectedCommitId = this.Repo.Branches[currentBranchName].Tip.Sha;
+            var expectedVersion = VersionFile.GetVersion(this.Repo.Branches[currentBranchName].Tip).Version.ToString();
+
+            var currentBranchOutput = jsonOutput.Property("CurrentBranch")?.Value as JObject;
+            Assert.NotNull(currentBranchOutput);
+
+            Assert.Equal(currentBranchName, currentBranchOutput.GetValue("Name")?.ToString());
+            Assert.Equal(expectedCommitId, currentBranchOutput.GetValue("Commit")?.ToString());
+            Assert.Equal(expectedVersion, currentBranchOutput.GetValue("Version")?.ToString());
+
+        }
+
+        // Check "NewBranch" output
+        {
+            var expectedCommitId = this.Repo.Branches[releaseBranchName].Tip.Sha;
+            var expectedVersion = VersionFile.GetVersion(this.Repo.Branches[releaseBranchName].Tip).Version.ToString();
+
+            var newBranchOutput = jsonOutput.Property("NewBranch")?.Value as JObject;
+            Assert.NotNull(newBranchOutput);
+
+            Assert.Equal(releaseBranchName, newBranchOutput.GetValue("Name")?.ToString());
+            Assert.Equal(expectedCommitId, newBranchOutput.GetValue("Commit")?.ToString());
+            Assert.Equal(expectedVersion, newBranchOutput.GetValue("Version")?.ToString());
+        }
+    }
+
+    [Fact]
+    public void PrepareRelease_JsonOutputWhenUpdatingReleaseBranch()
+    {
+        // create and configure repository
+        this.InitializeSourceControl();
+
+        // create version.json
+        var versionOptions = new VersionOptions()
+        {
+            Version = SemanticVersion.Parse("1.0"),
+            Release = new ReleaseOptions()
+            {
+                BranchName = "v{version}",
+                VersionIncrement = ReleaseVersionIncrement.Minor
+            }
+        };
+        this.WriteVersionFile(versionOptions);
+        var branchName = "v1.0";
+
+        // switch to release branch
+        Commands.Checkout(this.Repo, this.Repo.CreateBranch(branchName));
+
+        // run release preparation
+        var stdout = new StringWriter();
+        var releaseManager = new ReleaseManager(stdout);
+        releaseManager.PrepareRelease(this.RepoPath, outputMode: ReleaseManager.ReleaseManagerOutputMode.Json);
+
+
+        // Expected output:
+        // {
+        //     "CurrentBranch" : {
+        //         "Name" : "<NAME>",
+        //         "Commit" : "<COMMIT>",
+        //         "Version" : "<VERSION>",
+        //     },
+        //     "NewBranch" : null
+        // }
+
+        var jsonOutput = JObject.Parse(stdout.ToString());
+
+        // check "CurrentBranch"  output
+        {
+            var expectedCommitId = this.Repo.Branches[branchName].Tip.Sha;
+            var expectedVersion = VersionFile.GetVersion(this.Repo.Branches[branchName].Tip).Version.ToString();
+
+            var currentBranchOutput = jsonOutput.Property("CurrentBranch")?.Value as JObject;
+            Assert.NotNull(currentBranchOutput);
+
+            Assert.Equal(branchName, currentBranchOutput.GetValue("Name")?.ToString());
+            Assert.Equal(expectedCommitId, currentBranchOutput.GetValue("Commit")?.ToString());
+            Assert.Equal(expectedVersion, currentBranchOutput.GetValue("Version")?.ToString());
+
+        }
+        // Check "NewBranch" output
+        {
+            // no new branch was created, so "NewBranch" should be null
+            var newBranchOutput = jsonOutput.Property("NewBranch")?.Value as JObject;
+            Assert.Null(newBranchOutput);
+        }
+    }
+
     private void AssertError(Action testCode, ReleasePreparationError expectedError)
     {
         var ex = Assert.Throws<ReleasePreparationException>(testCode);