CircleCI vs. TravisCI for gorilla/mux - comparing maintainability, verbosity, DRY, etc. Ref: https://twitter.com/elithrar/status/1140342082768261120 & https://blog.questionable.services/article/building-go-projects-on-circle-ci/

.travis.yml

language: go


matrix:
  include:
    - go: 1.7.x
    - go: 1.8.x
    - go: 1.9.x
    - go: 1.10.x
    - go: 1.11.x
    - go: 1.x
      env: LATEST=true
    - go: tip
  allow_failures:
    - go: tip

install:
  - # Skip

script:
  - go get -t -v ./...
  - diff -u <(echo -n) <(gofmt -d .)
  - if [[ "$LATEST" = true ]]; then go vet .; fi
  - go test -v -race ./...

config.yml

version: 2.1

jobs:
  "test":
    parameters:
      version:
        type: string
        default: "latest"
      golint:
        type: boolean
        default: true
      modules:
        type: boolean
        default: true
      goproxy:
        type: string
        default: ""
    docker:
      - image: "circleci/golang:<< parameters.version >>"
    working_directory: /go/src/github.com/gorilla/mux
    environment:
      GO111MODULE: "on"
      GOPROXY: "<< parameters.goproxy >>"
    steps:
      - checkout
      - run:
          name: "Print the Go version"
          command: >
            go version
      - run:
          name: "Fetch dependencies"
          command: >
            if [[ << parameters.modules >> = true ]]; then
              go mod download
              export GO111MODULE=on
            else
              go get -v ./...
            fi
      # Only run gofmt, vet & lint against the latest Go version
      - run:
          name: "Run golint"
          command: >
            if [ << parameters.version >> = "latest" ] && [ << parameters.golint >> = true ]; then
              go get -u golang.org/x/lint/golint
              golint ./...
            fi
      - run:
          name: "Run gofmt"
          command: >
            if [[ << parameters.version >> = "latest" ]]; then
              diff -u <(echo -n) <(gofmt -d -e .)
            fi
      - run:
          name: "Run go vet"
          command: >
            if [[ << parameters.version >> = "latest" ]]; then
              go vet -v ./...
            fi
      - run:
          name: "Run go test (+ race detector)"
          command: >
            go test -v -race ./...

workflows:
  tests:
    jobs:
      - test:
          matrix:
            parameters:
              version: ["latest", "1.15", "1.14", "1.13", "1.12", "1.11"]

Updated to use matrix in CircleCI:

version: 2.1

jobs:
  "test":
    parameters:
      version:
        type: string
        default: "latest"
      golint:
        type: boolean
        default: true
      modules:
        type: boolean
        default: true
      goproxy:
        type: string
        default: ""
    docker:
      - image: "circleci/golang:<< parameters.version >>"
    working_directory: /go/src/github.com/gorilla/mux
    environment:
      GO111MODULE: "on"
      GOPROXY: "<< parameters.goproxy >>"
    steps:
      - checkout
      - run:
          name: "Print the Go version"
          command: >
            go version
      - run:
          name: "Fetch dependencies"
          command: >
            if [[ << parameters.modules >> = true ]]; then
              go mod download
              export GO111MODULE=on
            else
              go get -v ./...
            fi
      # Only run gofmt, vet & lint against the latest Go version
      - run:
          name: "Run golint"
          command: >
            if [ << parameters.version >> = "latest" ] && [ << parameters.golint >> = true ]; then
              go get -u golang.org/x/lint/golint
              golint ./...
            fi
      - run:
          name: "Run gofmt"
          command: >
            if [[ << parameters.version >> = "latest" ]]; then
              diff -u <(echo -n) <(gofmt -d -e .)
            fi
      - run:
          name: "Run go vet"
          command: >
            if [[ << parameters.version >> = "latest" ]]; then
              go vet -v ./...
            fi
      - run:
          name: "Run go test (+ race detector)"
          command: >
            go test -v -race ./...

workflows:
  tests:
    jobs:
      - test:
          matrix:
            parameters:
              version: ["latest", "1.15", "1.14", "1.13", "1.12", "1.11"]