Add simple testing with shell.

.gitignore

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+test
+main
+main.sh

test.sh

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+#!/usr/bin/env sh
+
+# This file takes as an argument the .envrc file where variables are defined.
+if [ -z "$1" ]
+then
+  echo "Please provide the path to the .envrc file"
+  exit 1
+fi
+
+ENVRC="$1"
+
+# Use a variant of the program to see input and output to the program.
+go build main.go
+echo -e "#!/usr/bin/env sh\n\ntee -a ../input.log | ../../main | tee -a ../output.log >&1\n" > main.sh
+chmod +x main.sh
+
+rm -rf test
+mkdir test
+cd test && (
+  mkdir fake-remote-repo && cd fake-remote-repo
+  git init --bare
+  cd ..
+  git clone --progress fake-remote-repo local-repo &&\
+    cd local-repo && (
+      git lfs install --local
+      git lfs track "*.bin"
+      git add .gitattributes
+      git config --add lfs.customtransfer.lfs-s3.path ../../main.sh
+      git config --add lfs.standalonetransferagent lfs-s3
+      git commit -m "Adding .gitattributes"
+      echo "# This is a lfs-s3 test." > README.md
+      dd if=/dev/urandom of=1mb-blob.bin bs=1024 count=1024
+      git add README.md 1mb-blob.bin
+      git commit -m "Adding files"
+      source "$ENVRC"
+      GIT_TRACE=1 git push origin master
+      git remote -v
+    ) && cd ..
+  git clone --progress fake-remote-repo local-repo-dup &&\
+    cd local-repo-dup && (
+      git lfs install --local
+      git config --add lfs.customtransfer.lfs-s3.path ../../main.sh
+      git config --add lfs.standalonetransferagent lfs-s3
+      source "$ENVRC"
+      git reset --hard master
+      git lfs pull
+    )
+)