Add exception messages for data source and entities

src/Cli.Tests/TestHelper.cs

@@ -119,16 +119,21 @@ public static Process ExecuteDabCommand(string command, string flags)
             }
         ";
 
-        public const string RUNTIME_SECTION = @"
+        public const string RUNTIME_SECTION_WITH_EMPTY_ENTITIES = RUNTIME_SECTION + "," + @"""entities"": {}";
+
+        /// <summary>
+        /// Runtime section containing both rest and graphql disabled.
+        /// This is used for validating config to test that exceptions are thrown when both rest and graphql are disabled.
+        /// </summary>
+        public const string RUNTIME_SECTION_WITH_DISABLED_REST_GRAPHQL = @"
           ""runtime"": {
               ""rest"": {
                   ""path"": ""/api"",
-                  ""enabled"": true,
-                  ""request-body-strict"": true
+                  ""enabled"": false
               },
               ""graphql"": {
                   ""path"": ""/graphql"",
-                  ""enabled"": true,
+                  ""enabled"": false,
                   ""allow-introspection"": true
               },
               ""host"": {
@@ -145,18 +150,17 @@ public static Process ExecuteDabCommand(string command, string flags)
           ""entities"": {}";
 
         /// <summary>
-        /// Runtime section containing both rest and graphql disabled.
-        /// This is used for validating config to test that exceptions are thrown when both rest and graphql are disabled.
+        /// Only Runtime section containing both rest and graphql enabled.
         /// </summary>
-        public const string RUNTIME_SECTION_WITH_DISABLED_REST_GRAPHQL = @"
+        public const string RUNTIME_SECTION = @"
           ""runtime"": {
               ""rest"": {
                   ""path"": ""/api"",
-                  ""enabled"": false
+                  ""enabled"": true
               },
               ""graphql"": {
                   ""path"": ""/graphql"",
-                  ""enabled"": false,
+                  ""enabled"": true,
                   ""allow-introspection"": true
               },
               ""host"": {
@@ -169,8 +173,7 @@ public static Process ExecuteDabCommand(string command, string flags)
                       ""provider"": ""StaticWebApps""
                   }
               }
-          },
-          ""entities"": {}";
+          }";
 
         /// <summary>
         /// Configuration with unresolved environment variable references on
@@ -237,16 +240,16 @@ public static Process ExecuteDabCommand(string command, string flags)
         /// <summary>
         /// A minimal valid config json without any entities. This config string is used in unit tests.
         /// </summary>
-        public const string INITIAL_CONFIG = $"{{{SAMPLE_SCHEMA_DATA_SOURCE},{RUNTIME_SECTION}}}";
-        public const string INITIAL_COSMOSDB_NOSQL_CONFIG = $"{{{SAMPLE_SCHEMA_DATA_SOURCE_COSMOSDB_NOSQL},{RUNTIME_SECTION}}}";
+        public const string INITIAL_CONFIG = $"{{{SAMPLE_SCHEMA_DATA_SOURCE},{RUNTIME_SECTION_WITH_EMPTY_ENTITIES}}}";
+        public const string INITIAL_COSMOSDB_NOSQL_CONFIG = $"{{{SAMPLE_SCHEMA_DATA_SOURCE_COSMOSDB_NOSQL},{RUNTIME_SECTION_WITH_EMPTY_ENTITIES}}}";
 
         /// <summary>
         /// A minimal config json without any entities. This config is invalid as it contains an empty connection
         /// string. This config is used in tests to verify validation failures.
         /// </summary>
-        public const string INVALID_INTIAL_CONFIG = $"{{{SAMPLE_SCHEMA_DATA_SOURCE_WITH_INVALID_CONNSTRING},{RUNTIME_SECTION}}}";
+        public const string INVALID_INTIAL_CONFIG = $"{{{SAMPLE_SCHEMA_DATA_SOURCE_WITH_INVALID_CONNSTRING},{RUNTIME_SECTION_WITH_EMPTY_ENTITIES}}}";
 
-        public const string CONFIG_WITH_CUSTOM_PROPERTIES = $"{{{SAMPLE_DATA_SOURCE_WITH_CUSTOM_PROPERTIES},{RUNTIME_SECTION}}}";
+        public const string CONFIG_WITH_CUSTOM_PROPERTIES = $"{{{SAMPLE_DATA_SOURCE_WITH_CUSTOM_PROPERTIES},{RUNTIME_SECTION_WITH_EMPTY_ENTITIES}}}";
 
         public const string CONFIG_WITH_DISABLED_GLOBAL_REST_GRAPHQL = $"{{{SAMPLE_SCHEMA_DATA_SOURCE},{RUNTIME_SECTION_WITH_DISABLED_REST_GRAPHQL}}}";
 

src/Cli.Tests/ValidateConfigTests.cs

@@ -145,6 +145,52 @@ public void TestValidateConfigFailsWithInvalidGraphQLDepthLimit(object? depthLim
         }
     }
 
+    /// <summary>
+    /// This Test is used to verify that the validate command is able to catch when data source field or entities field is missing.
+    /// </summary>
+    [TestMethod]
+    public void TestValidateConfigFailsWithNoEntities()
+    {
+        string ConfigWithoutEntities = $"{{{SAMPLE_SCHEMA_DATA_SOURCE},{RUNTIME_SECTION}}}";
+
+        // create an empty config file
+        ((MockFileSystem)_fileSystem!).AddFile(TEST_RUNTIME_CONFIG_FILE, ConfigWithoutEntities);
+
+        ValidateOptions validateOptions = new(TEST_RUNTIME_CONFIG_FILE);
+
+        try
+        {
+            Assert.IsFalse(ConfigGenerator.IsConfigValid(validateOptions, _runtimeConfigLoader!, _fileSystem!));
+        }
+        catch (Exception ex)
+        {
+            Assert.Fail($"Unexpected Exception thrown: {ex.Message}");
+        }
+    }
+
+    /// <summary>
+    /// This Test is used to verify that the validate command is able to catch when data source field is missing.
+    /// </summary>
+    [TestMethod]
+    public void TestValidateConfigFailsWithNoDataSource()
+    {
+        string ConfigWithoutDataSource = $"{{{SCHEMA_PROPERTY},{RUNTIME_SECTION_WITH_EMPTY_ENTITIES}}}";
+
+        // create an empty config file
+        ((MockFileSystem)_fileSystem!).AddFile(TEST_RUNTIME_CONFIG_FILE, ConfigWithoutDataSource);
+
+        ValidateOptions validateOptions = new(TEST_RUNTIME_CONFIG_FILE);
+
+        try
+        {
+            Assert.IsFalse(ConfigGenerator.IsConfigValid(validateOptions, _runtimeConfigLoader!, _fileSystem!));
+        }
+        catch (Exception ex)
+        {
+            Assert.Fail($"Unexpected Exception thrown: {ex.Message}");
+        }
+    }
+
     /// <summary>
     /// This method implicitly validates that RuntimeConfigValidator::ValidateConfigSchema(...) successfully
     /// executes against a config file referencing environment variables.

src/Config/ObjectModel/RuntimeConfig.cs

@@ -191,13 +191,29 @@ public RuntimeConfig(
         this.Entities = Entities;
         this.DefaultDataSourceName = Guid.NewGuid().ToString();
 
+        if (this.DataSource is null)
+        {
+            throw new DataApiBuilderException(
+                message: "DataSource is a mandatory property in DAB Config",
+                statusCode: HttpStatusCode.UnprocessableEntity,
+                subStatusCode: DataApiBuilderException.SubStatusCodes.ConfigValidationError);
+        }
+
         // we will set them up with default values
         _dataSourceNameToDataSource = new Dictionary<string, DataSource>
         {
             { this.DefaultDataSourceName, this.DataSource }
         };
 
         _entityNameToDataSourceName = new Dictionary<string, string>();
+        if (Entities is null)
+        {
+            throw new DataApiBuilderException(
+                message: "Entities is a mandatory property in DAB Config",
+                statusCode: HttpStatusCode.UnprocessableEntity,
+                subStatusCode: DataApiBuilderException.SubStatusCodes.ConfigValidationError);
+        }
+
         foreach (KeyValuePair<string, Entity> entity in Entities)
         {
             _entityNameToDataSourceName.TryAdd(entity.Key, this.DefaultDataSourceName);