Remove faulty error type checks.

These type checks were not doing anything - which was surfaced by a `go vet` run on the more recent
Go version. errors.As with the second argument of type *error will always return true.

I played a little bit with trying to get a working typecheck in this test, but it didn't really work
because of issues with the fork github.com/Clever/syslogparser. Since that parser didn't update
self-references to point to itself instead of the upstream, our errors returned by this are already
not really working correctly - sometimes they are Clever/syslogparser.ParseError and sometimes
jeromer/syslogparser.ParseError. Fixing the underlying problem is out of scope for right now.

decode/decode_test.go

@@ -1,7 +1,6 @@
 package decode
 
 import (
-	"errors"
 	"fmt"
 	"sort"
 	"testing"
@@ -222,7 +221,6 @@ func TestSyslogDecoding(t *testing.T) {
 			fields, err := FieldsFromSyslog(spec.Input)
 			if spec.ExpectedError != nil {
 				assert.Error(err)
-				assert.True(errors.As(err, &spec.ExpectedError))
 				return
 			}
 			assert.NoError(err)
@@ -547,7 +545,6 @@ select sleep(2);`,
 			fields, err := ParseAndEnhance(spec.Line, "deploy-env")
 			if spec.ExpectedError != nil {
 				assert.Error(err)
-				assert.True(errors.As(err, &spec.ExpectedError))
 				return
 			}
 			assert.NoError(err)
@@ -557,7 +554,6 @@ select sleep(2);`,
 }
 
 func TestGetContainerMeta(t *testing.T) {
-
 	type containerMetaSpec struct {
 		description       string
 		input             map[string]interface{}

golang.mk

@@ -1,7 +1,7 @@
 # This is the default Clever Golang Makefile.
 # It is stored in the dev-handbook repo, github.com/Clever/dev-handbook
 # Please do not alter this file directly.
-GOLANG_MK_VERSION := 1.0.0
+GOLANG_MK_VERSION := 1.1.0
 
 SHELL := /bin/bash
 SYSTEM := $(shell uname -a | cut -d" " -f1 | tr '[:upper:]' '[:lower:]')
@@ -11,7 +11,7 @@ SYSTEM := $(shell uname -a | cut -d" " -f1 | tr '[:upper:]' '[:lower:]')
 export TZ=UTC
 
 # go build flags for use across all commands which accept them
-GO_BUILD_FLAGS := "-mod=vendor"
+export GOFLAGS := -mod=vendor $(GOFLAGS)
 
 # if the gopath includes several directories, use only the first
 GOPATH=$(shell echo $$GOPATH | cut -d: -f1)
@@ -39,7 +39,7 @@ endef
 # so we're defended against it breaking or changing in the future.
 FGT := $(GOPATH)/bin/fgt
 $(FGT):
-	go get github.com/GeertJohan/fgt@262f7b11eec07dc7b147c44641236f3212fee89d
+	go install -mod=readonly github.com/GeertJohan/fgt@262f7b11eec07dc7b147c44641236f3212fee89d
 
 golang-ensure-curl-installed:
 	@command -v curl >/dev/null 2>&1 || { echo >&2 "curl not installed. Please install curl."; exit 1; }
@@ -49,7 +49,7 @@ golang-ensure-curl-installed:
 # previously passing tests start failing without changing our code.
 GOLINT := $(GOPATH)/bin/golint
 $(GOLINT):
-	go get golang.org/x/lint/golint@738671d3881b9731cc63024d5d88cf28db875626
+	go install -mod=readonly golang.org/x/lint/golint@738671d3881b9731cc63024d5d88cf28db875626
 
 # golang-fmt-deps requires the FGT tool for checking output
 golang-fmt-deps: $(FGT)
@@ -89,7 +89,7 @@ golang-test-deps:
 # arg1: pkg path
 define golang-test
 @echo "TESTING $(1)..."
-@go test $(GO_BUILD_FLAGS) -v $(1)
+@go test -v $(1)
 endef
 
 # golang-test-strict-deps is here for consistency
@@ -99,7 +99,22 @@ golang-test-strict-deps:
 # arg1: pkg path
 define golang-test-strict
 @echo "TESTING $(1)..."
-@go test -v $(GO_BUILD_FLAGS) -race $(1)
+@go test -v -race $(1)
+endef
+
+# golang-test-strict-cover-deps is here for consistency
+golang-test-strict-cover-deps:
+
+# golang-test-strict-cover uses the Go toolchain to run all tests in the pkg with the race and cover flag.
+# appends coverage results to coverage.txt
+# arg1: pkg path
+define golang-test-strict-cover
+@echo "TESTING $(1)..."
+@go test -v -race -cover -coverprofile=profile.tmp -covermode=atomic $(1)
+@if [ -f profile.tmp ]; then \
+  cat profile.tmp | tail -n +2 >> coverage.txt; \
+  rm profile.tmp; \
+fi;
 endef
 
 # golang-vet-deps is here for consistency
@@ -109,7 +124,7 @@ golang-vet-deps:
 # arg1: pkg path
 define golang-vet
 @echo "VETTING $(1)..."
-@go vet $(GO_BUILD_FLAGS) $(1)
+@go vet $(1)
 endef
 
 # golang-test-all-deps installs all dependencies needed for different test cases.
@@ -137,19 +152,37 @@ $(call golang-vet,$(1))
 $(call golang-test-strict,$(1))
 endef
 
+# golang-test-all-strict-cover-deps: installs all dependencies needed for different test cases.
+golang-test-all-strict-cover-deps: golang-fmt-deps golang-lint-deps-strict golang-test-strict-cover-deps golang-vet-deps
+
+# golang-test-all-strict-cover calls fmt, lint, vet and test on the specified pkg with strict and cover
+# requirements that no errors are thrown while linting.
+# arg1: pkg path
+define golang-test-all-strict-cover
+$(call golang-fmt,$(1))
+$(call golang-lint-strict,$(1))
+$(call golang-vet,$(1))
+$(call golang-test-strict-cover,$(1))
+endef
+
 # golang-build: builds a golang binary. ensures CGO build is done during CI. This is needed to make a binary that works with a Docker alpine image.
 # arg1: pkg path
 # arg2: executable name
 define golang-build
-@echo "BUILDING..."
+@echo "BUILDING $(2)..."
 @if [ -z "$$CI" ]; then \
-	go build $(GO_BUILD_FLAGS) -o bin/$(2) $(1); \
+	go build -o bin/$(2) $(1); \
 else \
 	echo "-> Building CGO binary"; \
-	CGO_ENABLED=0 go build $(GO_BUILD_FLAGS) -installsuffix cgo -o bin/$(2) $(1); \
+	CGO_ENABLED=0 go build -installsuffix cgo -o bin/$(2) $(1); \
 fi;
 endef
 
+# golang-setup-coverage: set up the coverage file
+define golang-setup-coverage:
+	@echo "mode: atomic" > coverage.txt
+endef
+
 # golang-update-makefile downloads latest version of golang.mk
 golang-update-makefile:
 	@wget https://raw.githubusercontent.com/Clever/dev-handbook/master/make/golang-v1.mk -O /tmp/golang.mk 2>/dev/null