test: refactor and add comprehensive tests

BREAKING CHANGE:
* rework tests to not rely on external services
* add test run and coveralls to CI
* refactor options and allow for message-level overrides via `merge()`
* change meta format
  * Meta is now expected to be supplied as a valid JSON string
  * Meta is now properly marshalled to either a string or an object
    in the line payload depending on the IndexMeta option

Semver: major
Ref: LOG-6966,LOG-7026

.circleci/config.yml

@@ -15,8 +15,24 @@ jobs:
       - image: circleci/golang:1.14
     steps:
       - checkout
-      - run: go get -u golang.org/x/lint/golint
-      - run: golint -set_exit_status **/*.go
+      - run:
+          name: "Install test dependencies"
+          command: |
+            go get -u golang.org/x/lint/golint
+            go get github.com/mattn/goveralls
+      - run:
+          name: "Lint"
+          command: |
+            golint -set_exit_status **/*.go
+      - run:
+          name: "Run tests"
+          command: |
+            mkdir -p /tmp/artifacts
+            go test -v -coverprofile=/tmp/artifacts/profile.out -covermode=count ./logger
+            go tool cover -html=/tmp/artifacts/profile.out -o /tmp/artifacts/coverage.html
+            goveralls -coverprofile=/tmp/artifacts/profile.out -service=circleci -repotoken $COVERALLS_REPO_TOKEN
+      - store_artifacts:
+          path: /tmp/artifacts  
   build:
     machine: true
     steps:

.gitignore

@@ -1 +1,2 @@
 .DS_Store
+*.out

go.mod

@@ -2,4 +2,7 @@ module github.com/logdna/logdna-go
 
 go 1.14
 
-require github.com/joho/godotenv v1.3.0
+require (
+	github.com/joho/godotenv v1.3.0
+	github.com/stretchr/testify v1.6.1
+)

go.sum

@@ -1,2 +1,13 @@
+github.com/davecgh/go-spew v1.1.0 h1:ZDRjVQ15GmhC3fiQ8ni8+OwkZQO4DARzQgrnXU1Liz8=
+github.com/davecgh/go-spew v1.1.0/go.mod h1:J7Y8YcW2NihsgmVo/mv3lAwl/skON4iLHjSsI+c5H38=
 github.com/joho/godotenv v1.3.0 h1:Zjp+RcGpHhGlrMbJzXTrZZPrWj+1vfm90La1wgB6Bhc=
 github.com/joho/godotenv v1.3.0/go.mod h1:7hK45KPybAkOC6peb+G5yklZfMxEjkZhHbwpqxOKXbg=
+github.com/pmezard/go-difflib v1.0.0 h1:4DBwDE0NGyQoBHbLQYPwSUPoCMWR5BEzIk/f1lZbAQM=
+github.com/pmezard/go-difflib v1.0.0/go.mod h1:iKH77koFhYxTK1pcRnkKkqfTogsbg7gZNVY4sRDYZ/4=
+github.com/stretchr/objx v0.1.0 h1:4G4v2dO3VZwixGIRoQ5Lfboy6nUhCyYzaqnIAPPhYs4=
+github.com/stretchr/objx v0.1.0/go.mod h1:HFkY916IF+rwdDfMAkV7OtwuqBVzrE8GR6GFx+wExME=
+github.com/stretchr/testify v1.6.1 h1:hDPOHmpOpP40lSULcqw7IrRb/u7w6RpDC9399XyoNd0=
+github.com/stretchr/testify v1.6.1/go.mod h1:6Fq8oRcR53rry900zMqJjRRixrwX3KX962/h/Wwjteg=
+gopkg.in/check.v1 v0.0.0-20161208181325-20d25e280405/go.mod h1:Co6ibVJAznAaIkqp8huTwlJQCZ016jof/cbN4VW5Yz0=
+gopkg.in/yaml.v3 v3.0.0-20200313102051-9f266ea9e77c h1:dUUwHk2QECo/6vqA44rthZ8ie2QXMNeKRTHCNY2nXvo=
+gopkg.in/yaml.v3 v3.0.0-20200313102051-9f266ea9e77c/go.mod h1:K4uyk7z7BCEPqu6E+C64Yfv1cQ7kz7rIZviUmN+EgEM=