Construct arg vector manually rather than parse string

By constructing an arg vector manually, we no longer need to quote arguments

Mandate that args must be passed when building a command

Now you need to provide an args array when building a command.
There are a handful of places where we need to deal with a string,
such as with user-defined custom commands, and for those we now require
that at the callsite they use str.ToArgv to do that. I don't want
to provide a method out of the box for it because I want to discourage its
use.

For some reason we were invoking a command through a shell when amending a
commit, and I don't believe we needed to do that as there was nothing user-
supplied about the command. So I've switched to using a regular command out-
side the shell there

pkg/integration/tests/sync/fetch_prune.go

@@ -7,7 +7,7 @@ import (
 
 var FetchPrune = NewIntegrationTest(NewIntegrationTestArgs{
 	Description:  "Fetch from the remote with the 'prune' option set in the git config",
-	ExtraCmdArgs: "",
+	ExtraCmdArgs: []string{},
 	Skip:         false,
 	SetupConfig:  func(config *config.AppConfig) {},
 	SetupRepo: func(shell *Shell) {

pkg/integration/tests/sync/force_push.go

@@ -7,7 +7,7 @@ import (
 
 var ForcePush = NewIntegrationTest(NewIntegrationTestArgs{
 	Description:  "Push to a remote with new commits, requiring a force push",
-	ExtraCmdArgs: "",
+	ExtraCmdArgs: []string{},
 	Skip:         false,
 	SetupConfig:  func(config *config.AppConfig) {},
 	SetupRepo: func(shell *Shell) {

pkg/integration/tests/sync/force_push_multiple_matching.go

@@ -7,7 +7,7 @@ import (
 
 var ForcePushMultipleMatching = NewIntegrationTest(NewIntegrationTestArgs{
 	Description:  "Force push to multiple branches because the user has push.default matching",
-	ExtraCmdArgs: "",
+	ExtraCmdArgs: []string{},
 	Skip:         false,
 	SetupConfig: func(config *config.AppConfig) {
 	},

pkg/integration/tests/sync/force_push_multiple_upstream.go

@@ -7,7 +7,7 @@ import (
 
 var ForcePushMultipleUpstream = NewIntegrationTest(NewIntegrationTestArgs{
 	Description:  "Force push to only the upstream branch of the current branch because the user has push.default upstream",
-	ExtraCmdArgs: "",
+	ExtraCmdArgs: []string{},
 	Skip:         false,
 	SetupConfig:  func(config *config.AppConfig) {},
 	SetupRepo: func(shell *Shell) {

pkg/integration/tests/sync/pull.go

@@ -7,7 +7,7 @@ import (
 
 var Pull = NewIntegrationTest(NewIntegrationTestArgs{
 	Description:  "Pull a commit from the remote",
-	ExtraCmdArgs: "",
+	ExtraCmdArgs: []string{},
 	Skip:         false,
 	SetupConfig:  func(config *config.AppConfig) {},
 	SetupRepo: func(shell *Shell) {

pkg/integration/tests/sync/pull_and_set_upstream.go

@@ -7,7 +7,7 @@ import (
 
 var PullAndSetUpstream = NewIntegrationTest(NewIntegrationTestArgs{
 	Description:  "Pull a commit from the remote, setting the upstream branch in the process",
-	ExtraCmdArgs: "",
+	ExtraCmdArgs: []string{},
 	Skip:         false,
 	SetupConfig:  func(config *config.AppConfig) {},
 	SetupRepo: func(shell *Shell) {

pkg/integration/tests/sync/pull_merge.go

@@ -7,7 +7,7 @@ import (
 
 var PullMerge = NewIntegrationTest(NewIntegrationTestArgs{
 	Description:  "Pull with a merge strategy",
-	ExtraCmdArgs: "",
+	ExtraCmdArgs: []string{},
 	Skip:         false,
 	SetupConfig:  func(config *config.AppConfig) {},
 	SetupRepo: func(shell *Shell) {

pkg/integration/tests/sync/pull_merge_conflict.go

@@ -7,7 +7,7 @@ import (
 
 var PullMergeConflict = NewIntegrationTest(NewIntegrationTestArgs{
 	Description:  "Pull with a merge strategy, where a conflict occurs",
-	ExtraCmdArgs: "",
+	ExtraCmdArgs: []string{},
 	Skip:         false,
 	SetupConfig:  func(config *config.AppConfig) {},
 	SetupRepo: func(shell *Shell) {

pkg/integration/tests/sync/pull_rebase.go

@@ -7,7 +7,7 @@ import (
 
 var PullRebase = NewIntegrationTest(NewIntegrationTestArgs{
 	Description:  "Pull with a rebase strategy",
-	ExtraCmdArgs: "",
+	ExtraCmdArgs: []string{},
 	Skip:         false,
 	SetupConfig:  func(config *config.AppConfig) {},
 	SetupRepo: func(shell *Shell) {

pkg/integration/tests/sync/pull_rebase_conflict.go

@@ -7,7 +7,7 @@ import (
 
 var PullRebaseConflict = NewIntegrationTest(NewIntegrationTestArgs{
 	Description:  "Pull with a rebase strategy, where a conflict occurs",
-	ExtraCmdArgs: "",
+	ExtraCmdArgs: []string{},
 	Skip:         false,
 	SetupConfig:  func(config *config.AppConfig) {},
 	SetupRepo: func(shell *Shell) {

pkg/integration/tests/sync/pull_rebase_interactive_conflict.go

@@ -7,7 +7,7 @@ import (
 
 var PullRebaseInteractiveConflict = NewIntegrationTest(NewIntegrationTestArgs{
 	Description:  "Pull with an interactive rebase strategy, where a conflict occurs",
-	ExtraCmdArgs: "",
+	ExtraCmdArgs: []string{},
 	Skip:         false,
 	SetupConfig:  func(config *config.AppConfig) {},
 	SetupRepo: func(shell *Shell) {

pkg/integration/tests/sync/pull_rebase_interactive_conflict_drop.go

@@ -7,7 +7,7 @@ import (
 
 var PullRebaseInteractiveConflictDrop = NewIntegrationTest(NewIntegrationTestArgs{
 	Description:  "Pull with an interactive rebase strategy, where a conflict occurs. Also drop a commit while rebasing",
-	ExtraCmdArgs: "",
+	ExtraCmdArgs: []string{},
 	Skip:         false,
 	SetupConfig:  func(config *config.AppConfig) {},
 	SetupRepo: func(shell *Shell) {

pkg/integration/tests/sync/push.go

@@ -7,7 +7,7 @@ import (
 
 var Push = NewIntegrationTest(NewIntegrationTestArgs{
 	Description:  "Push a commit to a pre-configured upstream",
-	ExtraCmdArgs: "",
+	ExtraCmdArgs: []string{},
 	Skip:         false,
 	SetupConfig: func(config *config.AppConfig) {
 	},

pkg/integration/tests/sync/push_and_auto_set_upstream.go

@@ -7,7 +7,7 @@ import (
 
 var PushAndAutoSetUpstream = NewIntegrationTest(NewIntegrationTestArgs{
 	Description:  "Push a commit and set the upstream automatically as configured by git",
-	ExtraCmdArgs: "",
+	ExtraCmdArgs: []string{},
 	Skip:         false,
 	SetupConfig: func(config *config.AppConfig) {
 	},

pkg/integration/tests/sync/push_and_set_upstream.go

@@ -7,7 +7,7 @@ import (
 
 var PushAndSetUpstream = NewIntegrationTest(NewIntegrationTestArgs{
 	Description:  "Push a commit and set the upstream via a prompt",
-	ExtraCmdArgs: "",
+	ExtraCmdArgs: []string{},
 	Skip:         false,
 	SetupConfig:  func(config *config.AppConfig) {},
 	SetupRepo: func(shell *Shell) {

pkg/integration/tests/sync/push_follow_tags.go

@@ -7,7 +7,7 @@ import (
 
 var PushFollowTags = NewIntegrationTest(NewIntegrationTestArgs{
 	Description:  "Push with --follow-tags configured in git config",
-	ExtraCmdArgs: "",
+	ExtraCmdArgs: []string{},
 	Skip:         false,
 	SetupConfig: func(config *config.AppConfig) {
 	},

pkg/integration/tests/sync/push_no_follow_tags.go

@@ -7,7 +7,7 @@ import (
 
 var PushNoFollowTags = NewIntegrationTest(NewIntegrationTestArgs{
 	Description:  "Push with --follow-tags NOT configured in git config",
-	ExtraCmdArgs: "",
+	ExtraCmdArgs: []string{},
 	Skip:         true, // turns out this actually DOES push the tag. I have no idea why
 	SetupConfig: func(config *config.AppConfig) {
 	},

pkg/integration/tests/sync/push_tag.go

@@ -7,7 +7,7 @@ import (
 
 var PushTag = NewIntegrationTest(NewIntegrationTestArgs{
 	Description:  "Push a specific tag",
-	ExtraCmdArgs: "",
+	ExtraCmdArgs: []string{},
 	Skip:         false,
 	SetupConfig: func(config *config.AppConfig) {
 	},

pkg/integration/tests/sync/push_with_credential_prompt.go

@@ -7,7 +7,7 @@ import (
 
 var PushWithCredentialPrompt = NewIntegrationTest(NewIntegrationTestArgs{
 	Description:  "Push a commit to a pre-configured upstream, where credentials are required",
-	ExtraCmdArgs: "",
+	ExtraCmdArgs: []string{},
 	Skip:         false,
 	SetupConfig: func(config *config.AppConfig) {
 	},

pkg/integration/tests/sync/rename_branch_and_pull.go

@@ -7,7 +7,7 @@ import (
 
 var RenameBranchAndPull = NewIntegrationTest(NewIntegrationTestArgs{
 	Description:  "Rename a branch to no longer match its upstream, then pull from the upstream",
-	ExtraCmdArgs: "",
+	ExtraCmdArgs: []string{},
 	Skip:         false,
 	SetupConfig:  func(config *config.AppConfig) {},
 	SetupRepo: func(shell *Shell) {