Lint rule for making new contexts in tests (#1199)

## Description
Create a lint rule that warns if `context.TODO` or `context.Background` are called in tests. This helps standardize the use of `tester.NewContext` and ensures log messages are properly flushed during tests.

Output from the linter is similar to (sadly can't get rid of the `\\` in there)
```
pkg/services/m365/m365_test.go:49:22: use of `context.Background` forbidden because "tests should use tester\\.NewContext" (forbidigo) 
        ids, err := UserIDs(context.Background(), acct)
```

## Type of change

<!--- Please check the type of change your PR introduces: --->
- [ ] 🌻 Feature
- [ ] 🐛 Bugfix
- [ ] 🗺️ Documentation
- [ ] 🤖 Test
- [x] 💻 CI/Deployment
- [ ] 🐹 Trivial/Minor

## Issue(s)

* closes #1198 

## Test Plan

<!-- How will this be tested prior to merging.-->
- [x] 💪 Manual
- [ ] ⚡ Unit test
- [ ] 💚 E2E

src/.golangci.yml

@@ -7,6 +7,7 @@ linters:
     - gofmt
     - gofumpt
     - errcheck
+    - forbidigo
     - lll
     - misspell
     - revive
@@ -19,6 +20,11 @@ linters-settings:
       - default
       - prefix(github.com/alcionai/corso)
     skip-generated: true
+  forbidigo:
+    forbid:
+      # Don't allow creating contexts without logging in tests. Use an ignore
+      # lower down to ensure usages of this outside of tests aren't reported.
+      - 'context\.(Background|TODO)(# tests should use tester\.NewContext )?'
   lll:
     line-length: 120
   revive:
@@ -62,21 +68,31 @@ issues:
   max-same-issues: 50
   exclude-rules:
     - linters:
-      - revive
+        - revive
       text: "exported:.*details.DetailsModel by other packages, and that stutters"
     - linters:
-      - revive
+        - revive
       text: "exported:.*details.DetailsEntry by other packages, and that stutters"
     - linters:
-      - revive
+        - revive
       text: "exported:.*mock.MockModelStore by other packages, and that stutters"
     - linters:
-      - revive
+        - revive
       text: "unexported-return:.*unexported type selectors.exchangeCategory"
     - linters:
-      - revive
+        - revive
       text: "unexported-return:.*unexported type.*kopia.conn"
     - path: _test\.go
       linters:
-      - revive
+        - revive
       text: "import-shadowing:.*'suite' shadows"
+    # Don't output about context.Background or context.TODO in non-test files.
+    # Need complicated multi-part regex because golang doesn't support not regex
+    # operators for sequences of characters (only character sets). The below
+    # basically boils down to:
+    #   1. anything 4 characters long with .go suffix
+    #   2. anything >= 5 characters long that doesn't end in _test.go
+    - path: ^.{4}\.go|.*([^_].{4}|_[^t].{3}|_t[^e].{2}|_te[^s].{1}|_tes[^t])\.go
+      linters:
+        - forbidigo
+      text: "context.(Background|TODO)"

src/cli/print/print_test.go

@@ -22,6 +22,7 @@ func (suite *PrintUnitSuite) TestOnly() {
 	t := suite.T()
 	c := &cobra.Command{}
 	// cannot use tester.NewContext() here: circular imports
+	//nolint:forbidigo
 	ctx := SetRootCmd(context.Background(), c)
 	assert.NoError(t, Only(ctx, nil))
 	assert.True(t, c.SilenceUsage)

src/cli/restore/exchange_integration_test.go

@@ -181,6 +181,7 @@ func (suite *RestoreExchangeIntegrationSuite) TestExchangeRestoreCmd_badBoolFlag
 		}
 
 		suite.T().Run(set.String(), func(t *testing.T) {
+			//nolint:forbidigo
 			ctx := config.SetViper(context.Background(), suite.vpr)
 			ctx, flush := tester.WithContext(ctx)
 			defer flush()

src/internal/connector/onedrive/drive_test.go

@@ -1,7 +1,6 @@
 package onedrive
 
 import (
-	"context"
 	"strings"
 	"testing"
 
@@ -35,8 +34,10 @@ func (suite *OneDriveSuite) SetupSuite() {
 }
 
 func (suite *OneDriveSuite) TestCreateGetDeleteFolder() {
+	ctx, flush := tester.NewContext()
+	defer flush()
+
 	t := suite.T()
-	ctx := context.Background()
 	folderIDs := []string{}
 	folderName1 := "Corso_Folder_Test_" + common.FormatNow(common.SimpleTimeTesting)
 	folderElements := []string{folderName1}

src/internal/kopia/conn_test.go

@@ -151,7 +151,9 @@ func (suite *WrapperIntegrationSuite) TestCloseAfterWrap() {
 }
 
 func (suite *WrapperIntegrationSuite) TestOpenAfterClose() {
-	ctx := context.Background()
+	ctx, flush := tester.NewContext()
+	defer flush()
+
 	t := suite.T()
 
 	k, err := openKopiaRepo(t, ctx)

src/internal/kopia/wrapper_test.go

@@ -1065,6 +1065,7 @@ func (suite *KopiaSimpleRepoIntegrationSuite) SetupTest() {
 	t := suite.T()
 	expectedDirs := 6
 	expectedFiles := len(suite.filesByPath)
+	//nolint:forbidigo
 	suite.ctx, _ = logger.SeedLevel(context.Background(), logger.Development)
 	c, err := openKopiaRepo(t, suite.ctx)
 	require.NoError(t, err)

src/internal/observe/observe_test.go

@@ -36,6 +36,7 @@ func (suite *ObserveProgressUnitSuite) TestDoesThings() {
 	defer func() {
 		// don't cross-contaminate other tests.
 		observe.Complete()
+		//nolint:forbidigo
 		observe.SeedWriter(context.Background(), nil)
 	}()
 

src/pkg/services/m365/m365_test.go

@@ -1,7 +1,6 @@
 package m365
 
 import (
-	"context"
 	"testing"
 
 	"github.com/stretchr/testify/require"
@@ -44,9 +43,12 @@ func (suite *M365IntegrationSuite) TestUsers() {
 }
 
 func (suite *M365IntegrationSuite) TestUserIDs() {
+	ctx, flush := tester.NewContext()
+	defer flush()
+
 	acct := tester.NewM365Account(suite.T())
 
-	ids, err := UserIDs(context.Background(), acct)
+	ids, err := UserIDs(ctx, acct)
 	require.NoError(suite.T(), err)
 
 	require.NotNil(suite.T(), ids)
@@ -54,9 +56,12 @@ func (suite *M365IntegrationSuite) TestUserIDs() {
 }
 
 func (suite *M365IntegrationSuite) TestGetEmailAndUserID() {
+	ctx, flush := tester.NewContext()
+	defer flush()
+
 	acct := tester.NewM365Account(suite.T())
 
-	ids, err := GetEmailAndUserID(context.Background(), acct)
+	ids, err := GetEmailAndUserID(ctx, acct)
 	require.NoError(suite.T(), err)
 
 	require.NotNil(suite.T(), ids)