Define {small,medium,all}_tests via build tags

This enables partitioning of test suites via `go test -tags=..._tests`.

Added '{small,medium}-tests' targets to Makefile, extracted the
'static-checks' target, and redefined the 'test' target.

The 'medium-tests' command uses the '-count=1' flag to disable test
caching. This is the idiomatic way to disable test caching explicitly
per 'go help testflag'.

Updated .github/workflogs/run-tests.yaml to use '-tags=all_tests' where
appropriate and to use '-tags=small_tests' to run tests and collect
coverage. Renamed the "Test" step to "Run small tests" as well.

Added .vscode/settings.json to set "go.buildTags" to "all_tests". This
enables 'gopls' integration, "Test: Run All Tests", and other test
runner commands to continue working as normal. Hat tip for a helpful
hint to:
- https://www.ryanchapin.com/configuring-vscode-to-use-build-tags-in-golang-to-separate-integration-and-unit-test-code/

.github/workflows/run-tests.yaml

@@ -27,13 +27,15 @@ jobs:
           go fmt ./...
           result="$(git diff)" && echo "$result" && [[ -z "$result" ]]
           go vet ./...
-          go run honnef.co/go/tools/cmd/staticcheck ./...
+          go run honnef.co/go/tools/cmd/staticcheck -tags=all_tests ./...
 
       - name: Build
-        run: go build -v ./...
+        run: go build -v -tags=all_tests ./...
 
-      - name: Test
-        run: go test -covermode=count -coverprofile=coverage.out ./...
+      - name: Run small tests
+        run: |
+          go test -covermode=count -coverprofile=coverage.out \
+            -tags=small_tests ./...
 
       - name: Send test coverage to Coveralls.io
         uses: coverallsapp/github-action@v2

.vscode/settings.json

@@ -0,0 +1,3 @@
+{
+    "go.buildTags": "all_tests"
+}

Makefile

@@ -1,6 +1,9 @@
 SHELL := /bin/bash
 .POSIX:
-.PHONY: all clean delete deploy run-local sam-build coverage test build-Function
+.PHONY: all clean \
+	delete deploy run-local sam-build \
+	coverage test medium-tests small-tests static-checks\
+	build-Function
 
 # https://docs.aws.amazon.com/serverless-application-model/latest/developerguide/sam-cli-command-reference-sam-build.html#examples-makefile-identifier
 # https://docs.aws.amazon.com/lambda/latest/dg/golang-package.html
@@ -9,13 +12,21 @@ build-Function:
 	GOOS=linux GOARCH=amd64 CGO_ENABLED=0 go build -ldflags="-s -w" \
 		-o $(ARTIFACTS_DIR)/main lambda/main.go
 
-test:
-	go vet ./...
-	staticcheck ./...
-	go test ./...
+static-checks:
+	go vet -tags=all_tests ./...
+	go run honnef.co/go/tools/cmd/staticcheck -tags=all_tests ./...
+	go build -tags=all_tests ./...
+
+small-tests:
+	go test -tags=small_tests ./...
+
+medium-tests:
+	go test -tags=medium_tests -count=1 ./...
+
+test: static-checks small-tests medium-tests
 
 coverage:
-	go test -covermode=count -coverprofile=coverage.out ./...
+	go test -covermode=count -coverprofile=coverage.out -tags=small_tests ./...
 	go tool cover -html=coverage.out	
 
 sam-build: template.yml

db/database_test.go

@@ -1,3 +1,5 @@
+//go:build medium_tests || all_tests
+
 package db
 
 import (

email/address_test.go

@@ -1,3 +1,5 @@
+//go:build small_tests || all_tests
+
 package email
 
 import (

email/mailer_test.go

@@ -1,3 +1,5 @@
+//go:build small_tests || all_tests
+
 package email
 
 import (

handler/api_test.go

@@ -1,3 +1,5 @@
+//go:build small_tests || all_tests
+
 package handler
 
 import (

handler/event_test.go

@@ -1,3 +1,5 @@
+//go:build small_tests || all_tests
+
 package handler
 
 import (

handler/handler_test.go

@@ -1,3 +1,5 @@
+//go:build small_tests || all_tests
+
 package handler
 
 import (

handler/mailto_test.go

@@ -1,3 +1,5 @@
+//go:build small_tests || all_tests
+
 package handler
 
 import (

handler/options_test.go

@@ -1,3 +1,5 @@
+//go:build small_tests || all_tests
+
 package handler
 
 import (

handler/parser_test.go

@@ -1,3 +1,5 @@
+//go:build small_tests || all_tests
+
 package handler
 
 import (

handler/sns_test.go

@@ -1,3 +1,5 @@
+//go:build small_tests || all_tests
+
 package handler
 
 import (