Throwing FormatException when a required property from Microsoft.Extensions.DependencyModel is empy

src/libraries/Microsoft.Extensions.DependencyModel/src/DependencyContextJsonReader.cs

@@ -358,7 +358,14 @@ private List<Target> ReadTargets(ref Utf8JsonReader reader)
 
             while (reader.Read() && reader.IsTokenTypeProperty())
             {
-                targets.Add(ReadTarget(ref reader, reader.GetString()!));
+                string? targetName = reader.GetString();
+
+                if (string.IsNullOrEmpty(targetName))
+                {
+                    throw new FormatException(SR.Format(SR.RequiredFieldNotSpecified, nameof(targetName)));
+                }
+
+                targets.Add(ReadTarget(ref reader, targetName));
             }
 
             reader.CheckEndObject();
@@ -374,7 +381,14 @@ private Target ReadTarget(ref Utf8JsonReader reader, string targetName)
 
             while (reader.Read() && reader.IsTokenTypeProperty())
             {
-                libraries.Add(ReadTargetLibrary(ref reader, reader.GetString()!));
+                string? targetLibraryName = reader.GetString();
+
+                if (string.IsNullOrEmpty(targetLibraryName))
+                {
+                    throw new FormatException(SR.Format(SR.RequiredFieldNotSpecified, nameof(targetLibraryName)));
+                }
+
+                libraries.Add(ReadTargetLibrary(ref reader, targetLibraryName));
             }
 
             reader.CheckEndObject();
@@ -448,7 +462,16 @@ private IEnumerable<Dependency> ReadTargetLibraryDependencies(ref Utf8JsonReader
 
             while (reader.TryReadStringProperty(out string? name, out string? version))
             {
-                dependencies.Add(new Dependency(Pool(name)!, Pool(version)!));
+                if (string.IsNullOrEmpty(name))
+                {
+                    throw new FormatException(SR.Format(SR.RequiredFieldNotSpecified, nameof(name)));
+                }
+                if (string.IsNullOrEmpty(version))
+                {
+                    throw new FormatException(SR.Format(SR.RequiredFieldNotSpecified, nameof(version)));
+                }
+
+                dependencies.Add(new Dependency(Pool(name), Pool(version)));
             }
 
             reader.CheckEndObject();
@@ -464,7 +487,12 @@ private static List<string> ReadPropertyNames(ref Utf8JsonReader reader)
 
             while (reader.Read() && reader.IsTokenTypeProperty())
             {
-                string libraryName = reader.GetString()!;
+                string? libraryName = reader.GetString();
+
+                if (string.IsNullOrEmpty(libraryName))
+                {
+                    throw new FormatException(SR.Format(SR.RequiredFieldNotSpecified, nameof(libraryName)));
+                }
                 reader.Skip();
 
                 runtimes.Add(libraryName);
@@ -486,7 +514,12 @@ private static List<RuntimeFile> ReadRuntimeFiles(ref Utf8JsonReader reader)
                 string? assemblyVersion = null;
                 string? fileVersion = null;
 
-                string path = reader.GetString()!;
+                string? path = reader.GetString();
+
+                if (string.IsNullOrEmpty(path))
+                {
+                    throw new FormatException(SR.Format(SR.RequiredFieldNotSpecified, nameof(path)));
+                }
 
                 reader.ReadStartObject();
 
@@ -521,9 +554,16 @@ private List<RuntimeTargetEntryStub> ReadTargetLibraryRuntimeTargets(ref Utf8Jso
 
             while (reader.Read() && reader.IsTokenTypeProperty())
             {
+                string? runtimePath = reader.GetString();
+
+                if (string.IsNullOrEmpty(runtimePath))
+                {
+                    throw new FormatException(SR.Format(SR.RequiredFieldNotSpecified, nameof(runtimePath)));
+                }
+
                 var runtimeTarget = new RuntimeTargetEntryStub
                 {
-                    Path = reader.GetString()!
+                    Path = runtimePath
                 };
 
                 reader.ReadStartObject();
@@ -565,7 +605,13 @@ private List<ResourceAssembly> ReadTargetLibraryResources(ref Utf8JsonReader rea
 
             while (reader.Read() && reader.IsTokenTypeProperty())
             {
-                string path = reader.GetString()!;
+                string? path = reader.GetString();
+
+                if (string.IsNullOrEmpty(path))
+                {
+                    throw new FormatException(SR.Format(SR.RequiredFieldNotSpecified, nameof(path)));
+                }
+
                 string? locale = null;
 
                 reader.ReadStartObject();
@@ -599,7 +645,12 @@ private Dictionary<string, LibraryStub> ReadLibraries(ref Utf8JsonReader reader)
 
             while (reader.Read() && reader.IsTokenTypeProperty())
             {
-                string libraryName = reader.GetString()!;
+                string? libraryName = reader.GetString();
+
+                if (string.IsNullOrEmpty(libraryName))
+                {
+                    throw new FormatException(SR.Format(SR.RequiredFieldNotSpecified, nameof(libraryName)));
+                }
 
                 libraries.Add(Pool(libraryName), ReadOneLibrary(ref reader));
             }
@@ -650,10 +701,15 @@ private LibraryStub ReadOneLibrary(ref Utf8JsonReader reader)
 
             reader.CheckEndObject();
 
+            if (string.IsNullOrEmpty(type))
+            {
+                throw new FormatException(SR.Format(SR.RequiredFieldNotSpecified, nameof(type)));
+            }
+
             return new LibraryStub()
             {
                 Hash = hash,
-                Type = Pool(type)!,
+                Type = Pool(type),
                 Serviceable = serviceable,
                 Path = path,
                 HashPath = hashPath,
@@ -669,9 +725,14 @@ private static List<RuntimeFallbacks> ReadRuntimes(ref Utf8JsonReader reader)
 
             while (reader.Read() && reader.IsTokenTypeProperty())
             {
-                string runtime = reader.GetString()!;
+                string? runtime = reader.GetString();
                 string?[] fallbacks = reader.ReadStringArray();
 
+                if (string.IsNullOrEmpty(runtime))
+                {
+                    throw new FormatException(SR.Format(SR.RequiredFieldNotSpecified, nameof(runtime)));
+                }
+
                 runtimeFallbacks.Add(new RuntimeFallbacks(runtime, fallbacks));
             }
 

src/libraries/Microsoft.Extensions.DependencyModel/src/Resources/Strings.resx

@@ -1,17 +1,17 @@
 <?xml version="1.0" encoding="utf-8"?>
 <root>
   <!-- 
-    Microsoft ResX Schema
-
+    Microsoft ResX Schema 
+    
     Version 2.0
-
-    The primary goals of this format is to allow a simple XML format
-    that is mostly human readable. The generation and parsing of the
-    various data types are done through the TypeConverter classes
-    associated with the data types
-
+    
+    The primary goals of this format is to allow a simple XML format 
+    that is mostly human readable. The generation and parsing of the 
+    various data types are done through the TypeConverter classes 
+    associated with the data types.
+    
     Example:
-
+    
     ... ado.net/XML headers & schema ...
     <resheader name="resmimetype">text/microsoft-resx</resheader>
     <resheader name="version">2.0</resheader>
@@ -26,36 +26,36 @@
         <value>[base64 mime encoded string representing a byte array form of the .NET Framework object]</value>
         <comment>This is a comment</comment>
     </data>
-
-    There are any number of "resheader" rows that contain simple
+                
+    There are any number of "resheader" rows that contain simple 
     name/value pairs.
-
-    Each data row contains a name, and value. The row also contains a
-    type or mimetype. Type corresponds to a .NET class that support
-    text/value conversion through the TypeConverter architecture.
-    Classes that don't support this are serialized and stored with the
+    
+    Each data row contains a name, and value. The row also contains a 
+    type or mimetype. Type corresponds to a .NET class that support 
+    text/value conversion through the TypeConverter architecture. 
+    Classes that don't support this are serialized and stored with the 
     mimetype set.
-
-    The mimetype is used for serialized objects, and tells the
-    ResXResourceReader how to depersist the object. This is currently not
+    
+    The mimetype is used for serialized objects, and tells the 
+    ResXResourceReader how to depersist the object. This is currently not 
     extensible. For a given mimetype the value must be set accordingly:
-
-    Note - application/x-microsoft.net.object.binary.base64 is the format
-    that the ResXResourceWriter will generate, however the reader can
+    
+    Note - application/x-microsoft.net.object.binary.base64 is the format 
+    that the ResXResourceWriter will generate, however the reader can 
     read any of the formats listed below.
-
+    
     mimetype: application/x-microsoft.net.object.binary.base64
     value   : The object must be serialized with 
             : System.Runtime.Serialization.Formatters.Binary.BinaryFormatter
             : and then encoded with base64 encoding.
-
+    
     mimetype: application/x-microsoft.net.object.soap.base64
-    value   : The object must be serialized with
+    value   : The object must be serialized with 
             : System.Runtime.Serialization.Formatters.Soap.SoapFormatter
             : and then encoded with base64 encoding.
 
     mimetype: application/x-microsoft.net.object.bytearray.base64
-    value   : The object must be serialized into a byte array
+    value   : The object must be serialized into a byte array 
             : using a System.ComponentModel.TypeConverter
             : and then encoded with base64 encoding.
     -->
@@ -138,4 +138,7 @@
   <data name="DuplicateItem" xml:space="preserve">
     <value>An item with the same key has already been added. Key: {0}</value>
   </data>
-</root>
+  <data name="RequiredFieldNotSpecified" xml:space="preserve">
+    <value>The required field '{0}' was not specified.</value>
+  </data>
+</root>

src/libraries/Microsoft.Extensions.DependencyModel/tests/DependencyContextJsonReaderTest.cs

@@ -792,5 +792,48 @@ public void IgnoresUnknownPropertiesInCompilationOptions()
             context.CompilationOptions.PublicSign.Should().Be(true);
             context.CompilationOptions.WarningsAsErrors.Should().Be(true);
         }
+
+        [Fact]
+        public void FailsToReadNullLibraryType()
+        {
+            Assert.Throws<FormatException>(() => Read(
+@"{
+    ""libraries"":{
+        ""System.Banana/1.0.0"": {
+            ""type"": null,
+            ""serviceable"": false,
+            ""sha512"": ""HASH-System.Banana""
+        }
+    }
+}
+"));
+        }
+
+        [Fact]
+        public void FailsToReadEmptyTargetName()
+        {
+            Assert.Throws<FormatException>(() => Read(
+@"{
+     ""targets"": {
+        """": {}
+    }
+ }"));
+        }
+
+        [Fact]
+        public void FailsToReadEmptyLibraryType()
+        {
+            Assert.Throws<FormatException>(() => Read(
+@"{
+    ""libraries"":{
+        ""System.Banana/1.0.0"": {
+            ""type"": """",
+            ""serviceable"": false,
+            ""sha512"": ""HASH-System.Banana""
+        }
+    }
+}
+"));
+        }
     }
 }