Creating function default function secret if file does not exist

Author: fabiocav

src/WebJobs.Script.WebHost/Security/SecretManager.cs

@@ -120,8 +120,15 @@ public virtual IDictionary<string, string> GetFunctionSecrets(string functionNam
                 string secretsFilePath = GetFunctionSecretsFilePath(functionName);
                 if (!TryLoadFunctionSecrets(functionName, out secrets, secretsFilePath))
                 {
-                    // initialize an empty FunctionSecrets instance
-                    secrets = new FunctionSecrets();
+                    secrets = new FunctionSecrets
+                    {
+                        Keys = new List<Key>
+                        {
+                            GenerateKey(ScriptConstants.DefaultFunctionKeyName)
+                        }
+                    };
+
+                    PersistSecrets(secrets, secretsFilePath);
                 }
 
                 // Read all secrets, which will run the keys through the appropriate readers

test/WebJobs.Script.Tests/Security/SecretManagerTests.cs

@@ -216,7 +216,7 @@ public void GetHostSecrets_WhenNoHostSecretFileExists_GeneratesSecretsAndPersist
         }
 
         [Fact]
-        public void GetFunctionSecrets_WhenNoSecretFileExists_ReturnsEmptySecretsAndDoesNotPersistsFile()
+        public void GetFunctionSecrets_WhenNoSecretFileExists_CreatesDefaultSecretAndPersistsFile()
         {
             var secretsPath = Path.Combine(Path.GetTempPath(), Guid.NewGuid().ToString());
             try
@@ -234,8 +234,9 @@ public void GetFunctionSecrets_WhenNoSecretFileExists_ReturnsEmptySecretsAndDoes
                     bool functionSecretsExists = File.Exists(Path.Combine(secretsPath, "testfunction.json"));
 
                     Assert.NotNull(functionSecrets);
-                    Assert.False(functionSecretsExists);
-                    Assert.Equal(0, functionSecrets.Count);
+                    Assert.True(functionSecretsExists);
+                    Assert.Equal(1, functionSecrets.Count);
+                    Assert.Equal(ScriptConstants.DefaultFunctionKeyName, functionSecrets.Keys.First());
                 }
             }
             finally