Add csharp compatibility tests against v3.0.0 and run on Travis.

csharp/compatibility_tests/v3.0.0/test.sh

+#!/bin/bash
+
+function run_test() {
+  # Generate test proto files.
+  ./protoc_1 -Iprotos/src -I../../../src/ --csharp_out=src/Google.Protobuf.Test \
+    --csharp_opt=base_namespace=Google.Protobuf \
+    protos/src/google/protobuf/unittest_import_proto3.proto \
+    protos/src/google/protobuf/unittest_import_public_proto3.proto \
+    protos/src/google/protobuf/unittest_well_known_types.proto
+
+  ./protoc_1 -Iprotos/csharp --csharp_out=src/Google.Protobuf.Test \
+    --csharp_opt=base_namespace=UnitTest.Issues \
+    protos/csharp/protos/unittest_issues.proto
+
+  ./protoc_2 -Iprotos/src --csharp_out=src/Google.Protobuf.Test \
+    --csharp_opt=base_namespace=Google.Protobuf \
+    protos/src/google/protobuf/unittest_proto3.proto \
+    protos/src/google/protobuf/map_unittest_proto3.proto
+
+  # Build and test.
+  dotnet build -c release src/Google.Protobuf src/Google.Protobuf.Test
+  dotnet test -c release -f netcoreapp1.0 src/Google.Protobuf.Test
+}
+
+set -ex
+
+# Change to the script's directory.
+cd $(dirname $0)
+
+# Version of the tests (i.e., the version of protobuf from where we extracted
+# these tests).
+TEST_VERSION=3.0.0
+
+# The old version of protobuf that we are testing compatibility against. This
+# is usually the same as TEST_VERSION (i.e., we use the tests extracted from
+# that version to test compatibility of the newest runtime against it), but it
+# is also possible to use this same test set to test the compatibiilty of the
+# latest version against other versions.
+case "$1" in
+  ""|3.0.0)
+    OLD_VERSION=3.0.0
+    OLD_VERSION_PROTOC=http://repo1.maven.org/maven2/com/google/protobuf/protoc/3.0.0/protoc-3.0.0-linux-x86_64.exe
+    ;;
+  3.0.2)
+    OLD_VERSION=3.0.2
+    OLD_VERSION_PROTOC=http://repo1.maven.org/maven2/com/google/protobuf/protoc/3.0.2/protoc-3.0.2-linux-x86_64.exe
+    ;;
+  3.1.0)
+    OLD_VERSION=3.1.0
+    OLD_VERSION_PROTOC=http://repo1.maven.org/maven2/com/google/protobuf/protoc/3.1.0/protoc-3.1.0-linux-x86_64.exe
+    ;;
+  *)
+    echo "[ERROR]: Unknown version number: $1"
+    exit 1
+    ;;
+esac
+
+echo "Running compatibility tests with $OLD_VERSION"
+
+# Check protoc
+[ -f ../../../src/protoc ] || {
+  echo "[ERROR]: Please build protoc first."
+  exit 1
+}
+
+# Download old version protoc compiler (for linux).
+wget $OLD_VERSION_PROTOC -O old_protoc
+chmod +x old_protoc
+
+# Test source compatibility. In these tests we recompile everything against
+# the new runtime (including old version generated code).
+# Copy the new runtime and keys.
+cp ../../src/Google.Protobuf src/Google.Protobuf -r
+cp ../../keys . -r
+dotnet restore
+
+# Test A.1:
+#   proto set 1: use old version
+#   proto set 2 which may import protos in set 1: use old version
+cp old_protoc protoc_1
+cp old_protoc protoc_2
+run_test
+
+# Test A.2:
+#   proto set 1: use new version
+#   proto set 2 which may import protos in set 1: use old version
+cp ../../../src/protoc protoc_1
+cp old_protoc protoc_2
+run_test
+
+# Test A.3:
+#   proto set 1: use old version
+#   proto set 2 which may import protos in set 1: use new version
+cp old_protoc protoc_1
+cp ../../../src/protoc protoc_2
+run_test
+
+rm protoc_1
+rm protoc_2
+rm old_protoc
+rm keys -r
+rm src/Google.Protobuf -r

tests.sh

@@ -63,7 +63,7 @@ build_cpp_distcheck() {
   # List all files that should be included in the distribution package.
   git ls-files | grep "^\(java\|python\|objectivec\|csharp\|js\|ruby\|php\|cmake\|examples\)" |\
     grep -v ".gitignore" | grep -v "java/compatibility_tests" |\
-    grep -v "python/compatibility_tests" > dist.lst
+    grep -v "python/compatibility_tests" | grep -v "csharp/compatibility_tests" > dist.lst
   # Unzip the dist tar file.
   DIST=`ls *.tar.gz`
   tar -xf $DIST
@@ -119,6 +119,9 @@ build_csharp() {
   (cd csharp/src; dotnet restore)
   csharp/buildall.sh
   cd conformance && make test_csharp && cd ..
+
+  # Run csharp compatibility test between 3.0.0 and the current version.
+  csharp/compatibility_tests/v3.0.0/test.sh 3.0.0
 }
 
 build_golang() {