Add CI

.gitignore

@@ -1,2 +1,3 @@
 vendor
 bin
+.vscode

.travis.yml

@@ -0,0 +1,10 @@
+language: go
+
+go:
+- 1.12.x
+env:
+  - GO111MODULE=on
+script: 
+- ./ci/ensuremod.sh
+- ./ci/lint.sh 
+- go test -v ./...

ci/ensuremod.sh

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+#!/bin/bash
+
+# inspired by nhooyr's days as CI overlord
+
+set -eou pipefail
+
+function help() {
+  echo
+  echo "you may need to update go.mod/go.sum via:"
+  echo "go list all > /dev/null"
+  echo "go mod tidy"
+  exit 1
+}
+
+go list -mod=readonly all > /dev/null
+
+go mod tidy
+
+if [[ $(git diff --name-only) != "" ]]; then
+  git diff
+  help
+fi

ci/lint.sh

@@ -0,0 +1,17 @@
+#!/bin/bash
+
+# Inspired by nhooyr's days as CI overlord.
+
+set -euo pipefail
+
+files=$(gofmt -l -s .)
+
+if [ ! -z "$files" ]; 
+then
+  echo "The following files need to be formatted:"
+  echo "$files"
+  echo "Please run 'gofmt -w -s .'"
+  exit 1
+fi
+
+go vet -composites=false .