Consolidate workspace dependencies into one bundle

Author: brandonbloom

internal/etch/git.go

@@ -7,40 +7,17 @@ import (
 	"strings"
 )
 
+// Workspace captures the repository snapshot and working directory that an etch
+// invocation reasons about. All process, Git, and filesystem effects are routed
+// through its private dependency bundle.
 type Workspace struct {
 	CWD       string
 	Root      string
 	Head      string
 	Ref       string
 	Unborn    bool
 	Untracked bool
-	git       gitRunner
-	worktree  workingTreeFS
-	temp      workspaceTempStore
-	paths     workspacePaths
-}
-
-type workspaceDeps struct {
-	git      gitRunner
-	worktree workingTreeFS
-	temp     workspaceTempStore
-	paths    workspacePaths
-}
-
-func (d workspaceDeps) withDefaults() workspaceDeps {
-	if d.git == nil {
-		d.git = realGitRunner{}
-	}
-	if d.worktree == nil {
-		d.worktree = osWorkingTreeFS{}
-	}
-	if d.temp == nil {
-		d.temp = osWorkspaceTempStore{}
-	}
-	if d.paths == nil {
-		d.paths = osWorkspacePaths{}
-	}
-	return d
+	deps      workspaceDeps
 }
 
 // OpenWorkspace opens the process working directory. Prefer OpenWorkspaceAt
@@ -58,6 +35,7 @@ func openWorkspace(untracked bool, deps workspaceDeps) (*Workspace, error) {
 	return openWorkspaceAt(cwd, untracked, deps)
 }
 
+// OpenWorkspaceAt opens the Git worktree containing cwd.
 func OpenWorkspaceAt(cwd string, untracked bool) (*Workspace, error) {
 	return openWorkspaceAt(cwd, untracked, workspaceDeps{})
 }
@@ -95,7 +73,7 @@ func openWorkspaceAt(cwd string, untracked bool, deps workspaceDeps) (*Workspace
 	if err == nil {
 		ref = strings.TrimSpace(string(refBytes))
 	}
-	return &Workspace{CWD: cwd, Root: root, Head: head, Ref: ref, Unborn: unborn, Untracked: untracked, git: deps.git, worktree: deps.worktree, temp: deps.temp, paths: deps.paths}, nil
+	return &Workspace{CWD: cwd, Root: root, Head: head, Ref: ref, Unborn: unborn, Untracked: untracked, deps: deps}, nil
 }
 
 type ResolvedPath struct {

internal/etch/git_runner.go

@@ -22,10 +22,7 @@ type gitRunner interface {
 type realGitRunner struct{}
 
 func (w *Workspace) gitRunner() gitRunner {
-	if w.git != nil {
-		return w.git
-	}
-	return realGitRunner{}
+	return w.workspaceDeps().git
 }
 
 func (realGitRunner) output(dir string, env []string, args ...string) ([]byte, error) {

internal/etch/working_tree.go

@@ -19,10 +19,7 @@ type workingTreeFS interface {
 type osWorkingTreeFS struct{}
 
 func (w *Workspace) workingTreeFS() workingTreeFS {
-	if w.worktree != nil {
-		return w.worktree
-	}
-	return osWorkingTreeFS{}
+	return w.workspaceDeps().worktree
 }
 
 func (w *Workspace) readWorktreeFile(ch fileChange) ([]byte, bool, error) {

internal/etch/workspace_deps.go

@@ -0,0 +1,31 @@
+package etch
+
+// workspaceDeps is the private bundle of injectable Workspace boundaries. Tests
+// can replace a specific boundary, while production constructors leave the
+// bundle empty and receive OS/Git backed defaults.
+type workspaceDeps struct {
+	git      gitRunner
+	worktree workingTreeFS
+	temp     workspaceTempStore
+	paths    workspacePaths
+}
+
+func (d workspaceDeps) withDefaults() workspaceDeps {
+	if d.git == nil {
+		d.git = realGitRunner{}
+	}
+	if d.worktree == nil {
+		d.worktree = osWorkingTreeFS{}
+	}
+	if d.temp == nil {
+		d.temp = osWorkspaceTempStore{}
+	}
+	if d.paths == nil {
+		d.paths = osWorkspacePaths{}
+	}
+	return d
+}
+
+func (w *Workspace) workspaceDeps() workspaceDeps {
+	return w.deps.withDefaults()
+}

internal/etch/workspace_paths.go

@@ -17,10 +17,7 @@ type workspacePaths interface {
 type osWorkspacePaths struct{}
 
 func (w *Workspace) pathResolver() workspacePaths {
-	if w.paths != nil {
-		return w.paths
-	}
-	return osWorkspacePaths{}
+	return w.workspaceDeps().paths
 }
 
 func (osWorkspacePaths) getwd() (string, error) {

internal/etch/workspace_temp.go

@@ -21,10 +21,7 @@ type workspaceTempFile interface {
 type osWorkspaceTempStore struct{}
 
 func (w *Workspace) tempStore() workspaceTempStore {
-	if w.temp != nil {
-		return w.temp
-	}
-	return osWorkspaceTempStore{}
+	return w.workspaceDeps().temp
 }
 
 func (osWorkspaceTempStore) mkdir(pattern string) (string, error) {