Implement in WriteIntegration to only open file handle once

Author: DavidBoike

src/GitVersionCore.Tests/BuildAgents/GitHubActionsTests.cs

@@ -107,23 +107,17 @@ public void GetCurrentBranchShouldHandlePullRequests()
             result.ShouldBe("refs/pull/1/merge");
         }
 
-        [TestCase("Something", "1.0.0",
-            "Writing \"GitVersion_Something=1.0.0\" to the file at $GITHUB_ENV", "GitVersion_Something=1.0.0")]
-        public void GetSetParameterMessage(string key, string value, string expectedResult, string expectedFileResult)
+        [Test]
+        public void GetSetParameterMessage()
         {
             // Assert
             environment.GetEnvironmentVariable("GitVersion_Something").ShouldBeNullOrWhiteSpace();
 
             // Act
-            var result = buildServer.GenerateSetParameterMessage(key, value);
+            var result = buildServer.GenerateSetParameterMessage("GitVersion_Something", "1.0.0");
 
             // Assert
-            result.ShouldContain(s => true, 1);
-            result.ShouldBeEquivalentTo(new[] { expectedResult });
-            var resultLines = File.ReadAllLines(githubSetEnvironmentTempFilePath);
-            resultLines.ShouldContain(s => true, 1);
-            resultLines.ShouldBeEquivalentTo(new[] { expectedFileResult });
-
+            result.ShouldContain(s => true, 0);
         }
 
         [Test]
@@ -156,11 +150,20 @@ public void ShouldWriteIntegration()
                 "Executing GenerateSetVersionMessage for 'GitHubActions'.",
                 "",
                 "Executing GenerateBuildLogOutput for 'GitHubActions'.",
-                "Writing \"GitVersion_Major=1.0.0\" to the file at $GITHUB_ENV"
+                "Writing version variables to $GITHUB_ENV file for 'GitHubActions'."
             };
 
             string.Join(Environment.NewLine, list)
                 .ShouldBe(string.Join(Environment.NewLine, expected));
+
+            var expectedFileContents = new List<string>
+            {
+                "GitVersion_Major=1.0.0"
+            };
+
+            var actualFileContents = File.ReadAllLines(githubSetEnvironmentTempFilePath);
+
+            actualFileContents.ShouldBe(expectedFileContents);
         }
 
         [Test]

src/GitVersionCore/BuildAgents/GitHubActions.cs

@@ -29,36 +29,44 @@ public override string GenerateSetVersionMessage(VersionVariables variables)
 
         public override string[] GenerateSetParameterMessage(string name, string value)
         {
+            // There is no equivalent function in GitHub Actions.
+
+            return new string[0];
+        }
+
+        public override void WriteIntegration(System.Action<string> writer, VersionVariables variables, bool updateBuildNumber = true)
+        {
+            base.WriteIntegration(writer, variables, updateBuildNumber);
+
             // https://docs.github.com/en/free-pro-team@latest/actions/reference/workflow-commands-for-github-actions#environment-files
-            // However it's important that GitHub Actions does not parse the log output. The outgoing environment variables must be
-            // written to a temporary file (identified by the $GITHUB_ENV environment variable, which changes for every step in a workflow)
-            // which is then parsed. That file must also be UTF-8 or it will fail.
+            // The outgoing environment variables must be written to a temporary file (identified by the $GITHUB_ENV environment
+            // variable, which changes for every step in a workflow) which is then parsed. That file must also be UTF-8 or it will fail.
 
-            if (!string.IsNullOrWhiteSpace(value))
+            if (writer == null || !updateBuildNumber)
             {
-                var gitHubSetEnvFilePath = environment.GetEnvironmentVariable(GitHubSetEnvTempFileEnvironmentVariableName);
-                var assignment = $"GitVersion_{name}={value}";
+                return;
+            }
+
+            var gitHubSetEnvFilePath = environment.GetEnvironmentVariable(GitHubSetEnvTempFileEnvironmentVariableName);
 
-                if (gitHubSetEnvFilePath != null)
+            if (gitHubSetEnvFilePath != null)
+            {
+                writer($"Writing version variables to $GITHUB_ENV file for '{GetType().Name}'.");
+                using (var streamWriter = File.AppendText(gitHubSetEnvFilePath)) // Already uses UTF-8 as required by GitHub
                 {
-                    using (var streamWriter = File.AppendText(gitHubSetEnvFilePath)) // Already uses UTF-8 as required by GitHub
+                    foreach (var variable in variables)
                     {
-                        streamWriter.WriteLine(assignment);
+                        if (!string.IsNullOrEmpty(variable.Value))
+                        {
+                            streamWriter.WriteLine($"GitVersion_{variable.Key}={variable.Value}");
+                        }
                     }
-
-                    return new[]
-                    {
-                        $"Writing \"{assignment}\" to the file at ${GitHubSetEnvTempFileEnvironmentVariableName}"
-                    };
                 }
-
-                return new[]
-                {
-                    $"Unable to write \"{assignment}\" to ${GitHubSetEnvTempFileEnvironmentVariableName} because the environment variable is not set."
-                };
             }
-
-            return new string[0];
+            else
+            {
+                writer($"Unable to write GitVersion variables to ${GitHubSetEnvTempFileEnvironmentVariableName} because the environment variable is not set.");
+            }
         }
 
         public override string GetCurrentBranch(bool usingDynamicRepos)