Merge pull request #259 from AArnott/fix250

Improve handling of version.json parsing failures

Author: AArnott

src/NerdBank.GitVersioning.Tests/VersionOracleTests.cs

@@ -279,4 +279,25 @@ public void CanUseGitProjectRelativePathWithGitRepoRoot()
         oracle = VersionOracle.Create(Path.Combine(this.RepoPath, "otherChildProject"), this.RepoPath, null, null, "otherChildProject");
         Assert.Equal("1.1", oracle.MajorMinorVersion.ToString());
     }
+
+    [Fact]
+    public void VersionJsonWithoutVersion()
+    {
+        File.WriteAllText(Path.Combine(this.RepoPath, VersionFile.JsonFileName), "{}");
+        this.InitializeSourceControl();
+        var oracle = VersionOracle.Create(this.RepoPath);
+        Assert.Equal(0, oracle.Version.Major);
+        Assert.Equal(0, oracle.Version.Minor);
+    }
+
+    [Fact]
+    public void VersionJsonWithSingleIntegerForVersion()
+    {
+        File.WriteAllText(Path.Combine(this.RepoPath, VersionFile.JsonFileName), @"{""version"":""3""}");
+        this.InitializeSourceControl();
+        var ex = Assert.Throws<FormatException>(() => VersionOracle.Create(this.RepoPath));
+        Assert.Contains(this.Repo.Head.Commits.First().Sha, ex.Message);
+        Assert.Contains("\"3\"", ex.InnerException.Message);
+        this.Logger.WriteLine(ex.ToString());
+    }
 }

src/NerdBank.GitVersioning/SemanticVersionJsonConverter.cs

@@ -24,6 +24,10 @@ public override object ReadJson(JsonReader reader, Type objectType, object exist
                 {
                     return value;
                 }
+                else
+                {
+                    throw new FormatException($"The value \"{reader.Value}\" is not a valid semantic version.");
+                }
             }
 
             throw new NotSupportedException();

src/NerdBank.GitVersioning/VersionFile.cs

@@ -69,7 +69,19 @@ public static VersionOptions GetVersion(LibGit2Sharp.Commit commit, string repoR
                         versionJsonContent = sr.ReadToEnd();
                     }
 
-                    VersionOptions result = TryReadVersionJsonContent(versionJsonContent);
+                    VersionOptions result;
+                    try
+                    {
+                        result = TryReadVersionJsonContent(versionJsonContent);
+                    }
+                    catch (FormatException ex)
+                    {
+                        throw new FormatException(
+                            $"Failure while reading {JsonFileName} from commit {commit.Sha}. " +
+                            "Fix this commit with rebase if this is an error, or review this doc on how to migrate to Nerdbank.GitVersioning: " +
+                            "https://github.com/AArnott/Nerdbank.GitVersioning/blob/master/doc/migrating.md", ex);
+                    }
+
                     if (result?.Inherit ?? false)
                     {
                         if (parentDirectory != null)

src/NerdBank.GitVersioning/VersionOracle.cs

@@ -98,7 +98,7 @@ public VersionOracle(string projectDirectory, LibGit2Sharp.Repository repo, LibG
 
             this.VersionHeightOffset = this.VersionOptions?.BuildNumberOffsetOrDefault ?? 0;
 
-            this.PrereleaseVersion = this.ReplaceMacros(this.VersionOptions?.Version.Prerelease ?? string.Empty);
+            this.PrereleaseVersion = this.ReplaceMacros(this.VersionOptions?.Version?.Prerelease ?? string.Empty);
 
             this.CloudBuildNumberOptions = this.VersionOptions?.CloudBuild?.BuildNumberOrDefault ?? VersionOptions.CloudBuildNumberOptions.DefaultInstance;