diff --git a/src/csharp/Grpc.Core.Testing/TestServerCallContext.cs b/src/csharp/Grpc.Core.Testing/TestServerCallContext.cs
new file mode 100644
index 0000000..5418417
--- /dev/null
+++ b/src/csharp/Grpc.Core.Testing/TestServerCallContext.cs
@@ -0,0 +1,58 @@
+#region Copyright notice and license
+
+// Copyright 2015 gRPC authors.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+#endregion
+
+using System;
+using System.Threading;
+using System.Threading.Tasks;
+using Grpc.Core;
+
+namespace Grpc.Core.Testing
+{
+    /// <summary>
+    /// Creates test doubles for <c>ServerCallContext</c>.
+    /// </summary>
+    public static class TestServerCallContext
+    {
+        /// <summary>
+        /// Creates a test double for <c>ServerCallContext</c>. Only for testing.
+        /// Note: experimental API that can change or be removed without any prior notice.
+        /// </summary>
+        public static ServerCallContext Create(string method, string host, DateTime deadline, Metadata requestHeaders, CancellationToken cancellationToken,
+            string peer, AuthContext authContext, ContextPropagationToken contextPropagationToken,
+            Func<Metadata, Task> writeHeadersFunc, Func<WriteOptions> writeOptionsGetter, Action<WriteOptions> writeOptionsSetter)
+        {
+            return new ServerCallContext(null, method, host, deadline, requestHeaders, cancellationToken,
+                writeHeadersFunc, new WriteOptionsHolder(writeOptionsGetter, writeOptionsSetter),
+                () => peer, () => authContext, () => contextPropagationToken);
+        }
+
+        private class WriteOptionsHolder : IHasWriteOptions
+        {
+            Func<WriteOptions> writeOptionsGetter;
+            Action<WriteOptions> writeOptionsSetter;
+
+            public WriteOptionsHolder(Func<WriteOptions> writeOptionsGetter, Action<WriteOptions> writeOptionsSetter)
+            {
+                this.writeOptionsGetter = writeOptionsGetter;
+                this.writeOptionsSetter = writeOptionsSetter;
+            }
+
+            public WriteOptions WriteOptions { get => writeOptionsGetter(); set => writeOptionsSetter(value); }
+        }
+    }
+}
diff --git a/src/csharp/Grpc.Core/ServerCallContext.cs b/src/csharp/Grpc.Core/ServerCallContext.cs
index c63a4c4..74a7dea 100644
--- a/src/csharp/Grpc.Core/ServerCallContext.cs
+++ b/src/csharp/Grpc.Core/ServerCallContext.cs
@@ -36,14 +36,25 @@
         private readonly Metadata requestHeaders;
         private readonly CancellationToken cancellationToken;
         private readonly Metadata responseTrailers = new Metadata();
+        private readonly Func<Metadata, Task> writeHeadersFunc;
+        private readonly IHasWriteOptions writeOptionsHolder;
+        private readonly Lazy<AuthContext> authContext;
+        private readonly Func<string> testingOnlyPeerGetter;
+        private readonly Func<AuthContext> testingOnlyAuthContextGetter;
+        private readonly Func<ContextPropagationToken> testingOnlyContextPropagationTokenFactory;
 
         private Status status = Status.DefaultSuccess;
-        private Func<Metadata, Task> writeHeadersFunc;
-        private IHasWriteOptions writeOptionsHolder;
-        private Lazy<AuthContext> authContext;
 
         internal ServerCallContext(CallSafeHandle callHandle, string method, string host, DateTime deadline, Metadata requestHeaders, CancellationToken cancellationToken,
             Func<Metadata, Task> writeHeadersFunc, IHasWriteOptions writeOptionsHolder)
+            : this(callHandle, method, host, deadline, requestHeaders, cancellationToken, writeHeadersFunc, writeOptionsHolder, null, null, null)
+        {
+        }
+
+        // Additional constructor params should be used for testing only
+        internal ServerCallContext(CallSafeHandle callHandle, string method, string host, DateTime deadline, Metadata requestHeaders, CancellationToken cancellationToken,
+            Func<Metadata, Task> writeHeadersFunc, IHasWriteOptions writeOptionsHolder,
+            Func<string> testingOnlyPeerGetter, Func<AuthContext> testingOnlyAuthContextGetter, Func<ContextPropagationToken> testingOnlyContextPropagationTokenFactory)
         {
             this.callHandle = callHandle;
             this.method = method;
@@ -54,6 +65,9 @@
             this.writeHeadersFunc = writeHeadersFunc;
             this.writeOptionsHolder = writeOptionsHolder;
             this.authContext = new Lazy<AuthContext>(GetAuthContextEager);
+            this.testingOnlyPeerGetter = testingOnlyPeerGetter;
+            this.testingOnlyAuthContextGetter = testingOnlyAuthContextGetter;
+            this.testingOnlyContextPropagationTokenFactory = testingOnlyContextPropagationTokenFactory;
         }
 
         /// <summary>
@@ -73,6 +87,10 @@
         /// </summary>
         public ContextPropagationToken CreatePropagationToken(ContextPropagationOptions options = null)
         {
+            if (testingOnlyContextPropagationTokenFactory != null)
+            {
+                return testingOnlyContextPropagationTokenFactory();
+            }
             return new ContextPropagationToken(callHandle, deadline, cancellationToken, options);
         }
             
@@ -99,6 +117,10 @@
         {
             get
             {
+                if (testingOnlyPeerGetter != null)
+                {
+                    return testingOnlyPeerGetter();
+                }
                 // Getting the peer lazily is fine as the native call is guaranteed
                 // not to be disposed before user-supplied server side handler returns.
                 // Most users won't need to read this field anyway.
@@ -182,6 +204,10 @@
         {
             get
             {
+                if (testingOnlyAuthContextGetter != null)
+                {
+                    return testingOnlyAuthContextGetter();
+                }
                 return authContext.Value;
             }
         }
@@ -198,7 +224,7 @@
     /// <summary>
     /// Allows sharing write options between ServerCallContext and other objects.
     /// </summary>
-    public interface IHasWriteOptions
+    internal interface IHasWriteOptions
     {
         /// <summary>
         /// Gets or sets the write options.
diff --git a/templates/tools/dockerfile/test/python_jessie_x64/Dockerfile.template b/templates/tools/dockerfile/test/python_jessie_x64/Dockerfile.template
index dba6a22..e73b839 100644
--- a/templates/tools/dockerfile/test/python_jessie_x64/Dockerfile.template
+++ b/templates/tools/dockerfile/test/python_jessie_x64/Dockerfile.template
@@ -19,6 +19,10 @@
   <%include file="../../apt_get_basic.include"/>
   <%include file="../../gcp_api_libraries.include"/>
   <%include file="../../python_deps.include"/>
+  # Install pip and virtualenv for Python 3.4
+  RUN curl https://bootstrap.pypa.io/get-pip.py | python3.4
+  RUN python3.4 -m pip install virtualenv
+
   <%include file="../../run_tests_addons.include"/>
   # Define the default command.
   CMD ["bash"]
diff --git a/tools/dockerfile/test/python_jessie_x64/Dockerfile b/tools/dockerfile/test/python_jessie_x64/Dockerfile
index 41b670c..bd9d55e 100644
--- a/tools/dockerfile/test/python_jessie_x64/Dockerfile
+++ b/tools/dockerfile/test/python_jessie_x64/Dockerfile
@@ -68,6 +68,10 @@
 RUN pip install virtualenv
 RUN pip install futures==2.2.0 enum34==1.0.4 protobuf==3.5.2.post1 six==1.10.0 twisted==17.5.0
 
+# Install pip and virtualenv for Python 3.4
+RUN curl https://bootstrap.pypa.io/get-pip.py | python3.4
+RUN python3.4 -m pip install virtualenv
+
 # Prepare ccache
 RUN ln -s /usr/bin/ccache /usr/local/bin/gcc
 RUN ln -s /usr/bin/ccache /usr/local/bin/g++
diff --git a/tools/internal_ci/helper_scripts/prepare_build_macos_rc b/tools/internal_ci/helper_scripts/prepare_build_macos_rc
index d84bebd..d2b7769 100644
--- a/tools/internal_ci/helper_scripts/prepare_build_macos_rc
+++ b/tools/internal_ci/helper_scripts/prepare_build_macos_rc
@@ -69,6 +69,11 @@
 # set xcode version for Obj-C tests
 sudo xcode-select -switch /Applications/Xcode_9.2.app/Contents/Developer/
 
+# Disable some unwanted dotnet options
+export NUGET_XMLDOC_MODE=skip
+export DOTNET_SKIP_FIRST_TIME_EXPERIENCE=true
+export DOTNET_CLI_TELEMETRY_OPTOUT=true
+
 # TODO(jtattermusch): better debugging of clock skew, remove once not needed
 date
 
diff --git a/tools/internal_ci/helper_scripts/prepare_build_windows.bat b/tools/internal_ci/helper_scripts/prepare_build_windows.bat
index 9fa6860..f987f8a 100644
--- a/tools/internal_ci/helper_scripts/prepare_build_windows.bat
+++ b/tools/internal_ci/helper_scripts/prepare_build_windows.bat
@@ -34,4 +34,9 @@
 @rem Needed for big_query_utils
 python -m pip install google-api-python-client
 
+@rem Disable some unwanted dotnet options
+set NUGET_XMLDOC_MODE=skip
+set DOTNET_SKIP_FIRST_TIME_EXPERIENCE=true
+set DOTNET_CLI_TELEMETRY_OPTOUT=true
+
 git submodule update --init
diff --git a/tools/run_tests/helper_scripts/build_python.sh b/tools/run_tests/helper_scripts/build_python.sh
index b0a6f0f..cdcb2aa 100755
--- a/tools/run_tests/helper_scripts/build_python.sh
+++ b/tools/run_tests/helper_scripts/build_python.sh
@@ -112,10 +112,6 @@
 export GRPC_PYTHON_BUILD_WITH_CYTHON=1
 export LANG=en_US.UTF-8
 
-# Default python on the host to fall back to when instantiating e.g. the
-# virtualenv.
-HOST_PYTHON=${HOST_PYTHON:-python}
-
 # If ccache is available on Linux, use it.
 if [ "$(is_linux)" ]; then
   # We're not on Darwin (Mac OS X)
@@ -132,14 +128,9 @@
 # Perform build operations #
 ############################
 
-# Instantiate the virtualenv, preferring to do so from the relevant python
-# version. Even if these commands fail (e.g. on Windows due to name conflicts)
-# it's possible that the virtualenv is still usable and we trust the tester to
-# be able to 'figure it out' instead of us e.g. doing potentially expensive and
-# unnecessary error recovery by `rm -rf`ing the virtualenv.
-($PYTHON -m virtualenv "$VENV" ||
- $HOST_PYTHON -m virtualenv -p "$PYTHON" "$VENV" ||
- true)
+# Instantiate the virtualenv from the Python version passed in.
+$PYTHON -m pip install virtualenv
+$PYTHON -m virtualenv "$VENV"
 VENV_PYTHON=$(script_realpath "$VENV/$VENV_RELATIVE_PYTHON")
 
 # See https://github.com/grpc/grpc/issues/14815 for more context. We cannot rely