Merge pull request #51 from asdf-vm/tb/offline-tests

feat(golang-rewrite): offline Go tests

execute/testdata/script

@@ -0,0 +1,3 @@
+#!/usr/bin/env bash
+
+echo $@

git/git_test.go

@@ -5,35 +5,27 @@ import (
 	"path/filepath"
 	"testing"
 
+	"asdf/repotest"
+
 	"github.com/go-git/go-git/v5"
 	"github.com/go-git/go-git/v5/plumbing"
 	"github.com/stretchr/testify/assert"
 )
 
-// TODO: Switch to local repo so tests don't go over the network
-const (
-	testRepo       = "https://github.com/Stratus3D/asdf-lua"
-	testPluginName = "lua"
-)
-
 func TestPluginClone(t *testing.T) {
 	t.Run("when plugin name is valid but URL is invalid prints an error", func(t *testing.T) {
-		tempDir := t.TempDir()
-		directory := filepath.Join(tempDir, testPluginName)
-
-		plugin := NewRepo(directory)
+		plugin := NewRepo(t.TempDir())
 		err := plugin.Clone("foobar")
 
 		assert.ErrorContains(t, err, "unable to clone plugin: repository not found")
 	})
 
 	t.Run("clones provided Git URL to plugin directory when URL is valid", func(t *testing.T) {
-		tempDir := t.TempDir()
-		directory := filepath.Join(tempDir, testPluginName)
-
+		repoDir := generateRepo(t)
+		directory := t.TempDir()
 		plugin := NewRepo(directory)
-		err := plugin.Clone(testRepo)
 
+		err := plugin.Clone(repoDir)
 		assert.Nil(t, err)
 
 		// Assert plugin directory contains Git repo with bin directory
@@ -42,17 +34,17 @@ func TestPluginClone(t *testing.T) {
 
 		entries, err := os.ReadDir(directory + "/bin")
 		assert.Nil(t, err)
-		assert.Equal(t, 5, len(entries))
+		assert.Equal(t, 12, len(entries))
 	})
 }
 
 func TestPluginHead(t *testing.T) {
-	tempDir := t.TempDir()
-	directory := filepath.Join(tempDir, testPluginName)
+	repoDir := generateRepo(t)
+	directory := t.TempDir()
 
 	plugin := NewRepo(directory)
 
-	err := plugin.Clone(testRepo)
+	err := plugin.Clone(repoDir)
 	assert.Nil(t, err)
 
 	head, err := plugin.Head()
@@ -61,12 +53,12 @@ func TestPluginHead(t *testing.T) {
 }
 
 func TestPluginRemoteURL(t *testing.T) {
-	tempDir := t.TempDir()
-	directory := filepath.Join(tempDir, testPluginName)
+	repoDir := generateRepo(t)
+	directory := t.TempDir()
 
 	plugin := NewRepo(directory)
 
-	err := plugin.Clone(testRepo)
+	err := plugin.Clone(repoDir)
 	assert.Nil(t, err)
 
 	url, err := plugin.RemoteURL()
@@ -75,16 +67,16 @@ func TestPluginRemoteURL(t *testing.T) {
 }
 
 func TestPluginUpdate(t *testing.T) {
-	tempDir := t.TempDir()
-	directory := filepath.Join(tempDir, testPluginName)
+	repoDir := generateRepo(t)
+	directory := t.TempDir()
 
 	plugin := NewRepo(directory)
 
-	err := plugin.Clone(testRepo)
+	err := plugin.Clone(repoDir)
 	assert.Nil(t, err)
 
 	t.Run("returns error when plugin with name does not exist", func(t *testing.T) {
-		nonexistantPath := filepath.Join(tempDir, "nonexistant")
+		nonexistantPath := filepath.Join(directory, "nonexistant")
 		nonexistantPlugin := NewRepo(nonexistantPath)
 		updatedToRef, err := nonexistantPlugin.Update("")
 
@@ -96,7 +88,7 @@ func TestPluginUpdate(t *testing.T) {
 
 	t.Run("returns error when plugin repo does not exist", func(t *testing.T) {
 		badPluginName := "badplugin"
-		badPluginDir := filepath.Join(tempDir, badPluginName)
+		badPluginDir := filepath.Join(directory, badPluginName)
 		err := os.MkdirAll(badPluginDir, 0o777)
 		assert.Nil(t, err)
 
@@ -198,3 +190,12 @@ func checkoutPreviousCommit(path string) (string, error) {
 
 	return previousHash.String(), nil
 }
+
+func generateRepo(t *testing.T) string {
+	t.Helper()
+	tempDir := t.TempDir()
+	path, err := repotest.GeneratePlugin("dummy_plugin", tempDir, "lua")
+
+	assert.Nil(t, err)
+	return path
+}

go.mod

@@ -5,6 +5,7 @@ go 1.21.5
 require (
 	github.com/go-git/go-git/v5 v5.11.0
 	github.com/mitchellh/go-homedir v1.1.0
+	github.com/otiai10/copy v1.14.0
 	github.com/sethvargo/go-envconfig v1.0.0
 	github.com/stretchr/testify v1.8.4
 	github.com/urfave/cli/v2 v2.27.1
@@ -35,6 +36,7 @@ require (
 	golang.org/x/crypto v0.16.0 // indirect
 	golang.org/x/mod v0.12.0 // indirect
 	golang.org/x/net v0.19.0 // indirect
+	golang.org/x/sync v0.3.0 // indirect
 	golang.org/x/sys v0.15.0 // indirect
 	golang.org/x/tools v0.13.0 // indirect
 	gopkg.in/warnings.v0 v0.1.2 // indirect

go.sum

@@ -52,6 +52,10 @@ github.com/mitchellh/go-homedir v1.1.0 h1:lukF9ziXFxDFPkA1vsr5zpc1XuPDn/wFntq5mG
 github.com/mitchellh/go-homedir v1.1.0/go.mod h1:SfyaCUpYCn1Vlf4IUYiD9fPX4A5wJrkLzIz1N1q0pr0=
 github.com/onsi/gomega v1.27.10 h1:naR28SdDFlqrG6kScpT8VWpu1xWY5nJRCF3XaYyBjhI=
 github.com/onsi/gomega v1.27.10/go.mod h1:RsS8tutOdbdgzbPtzzATp12yT7kM5I5aElG3evPbQ0M=
+github.com/otiai10/copy v1.14.0 h1:dCI/t1iTdYGtkvCuBG2BgR6KZa83PTclw4U5n2wAllU=
+github.com/otiai10/copy v1.14.0/go.mod h1:ECfuL02W+/FkTWZWgQqXPWZgW9oeKCSQ5qVfSc4qc4w=
+github.com/otiai10/mint v1.5.1 h1:XaPLeE+9vGbuyEHem1JNk3bYc7KKqyI/na0/mLd/Kks=
+github.com/otiai10/mint v1.5.1/go.mod h1:MJm72SBthJjz8qhefc4z1PYEieWmy8Bku7CjcAqyUSM=
 github.com/pjbgf/sha1cd v0.3.0 h1:4D5XXmUUBUl/xQ6IjCkEAbqXskkq/4O7LmGn0AqMDs4=
 github.com/pjbgf/sha1cd v0.3.0/go.mod h1:nZ1rrWOcGJ5uZgEEVL1VUM9iRQiZvWdbZjkKyFzPPsI=
 github.com/pkg/errors v0.9.1 h1:FEBLx1zS214owpjy7qsBeixbURkuhQAwrK5UwLGTwt4=

pluginindex/pluginindex.go

@@ -63,7 +63,7 @@ func (p PluginIndex) Refresh() (bool, error) {
 		// directory empty, clone down repo
 		err := p.repo.Clone(p.url)
 		if err != nil {
-			return false, err
+			return false, fmt.Errorf("unable to initialize index: %w", err)
 		}
 
 		return touchFS(p.directory)
@@ -90,7 +90,7 @@ func (p PluginIndex) doUpdate() (bool, error) {
 	// commit is
 	_, err := p.repo.Update("")
 	if err != nil {
-		return false, err
+		return false, fmt.Errorf("unable to update plugin index: %w", err)
 	}
 
 	// Touch update file

pluginindex/pluginindex_test.go

@@ -9,13 +9,15 @@ import (
 	"time"
 
 	"asdf/git"
+	"asdf/repotest"
 
 	"github.com/stretchr/testify/assert"
 )
 
 const (
-	realIndexURL    = "https://github.com/asdf-vm/asdf-plugins.git"
+	mockIndexURL    = "https://github.com/asdf-vm/asdf-plugins.git"
 	badIndexURL     = "http://asdf-vm.com/non-existent"
+	fooPluginURL    = "http://example.com/foo"
 	elixirPluginURL = "https://github.com/asdf-vm/asdf-elixir.git"
 	erlangPluginURL = "https://github.com/asdf-vm/asdf-erlang.git"
 )
@@ -84,15 +86,22 @@ func writeMockPluginFile(dir, pluginName, pluginURL string) error {
 func TestGetPluginSourceURL(t *testing.T) {
 	t.Run("with Git returns a plugin url when provided name of existing plugin", func(t *testing.T) {
 		dir := t.TempDir()
-		pluginIndex := New(dir, realIndexURL, true, 0, &git.Repo{Directory: dir})
-		url, err := pluginIndex.GetPluginSourceURL("elixir")
+		indexDir := filepath.Join(dir, "index")
+		err := os.Mkdir(indexDir, 0o777)
 		assert.Nil(t, err)
-		assert.Equal(t, url, elixirPluginURL)
+
+		repoPath, err := repotest.GeneratePluginIndex(dir)
+		assert.Nil(t, err)
+
+		pluginIndex := New(indexDir, repoPath, true, 0, &git.Repo{Directory: indexDir})
+		url, err := pluginIndex.GetPluginSourceURL("foo")
+		assert.Nil(t, err)
+		assert.Equal(t, url, fooPluginURL)
 	})
 
 	t.Run("returns a plugin url when provided name of existing plugin", func(t *testing.T) {
 		dir := t.TempDir()
-		pluginIndex := New(dir, realIndexURL, true, 0, &MockIndex{Directory: dir})
+		pluginIndex := New(dir, mockIndexURL, true, 0, &MockIndex{Directory: dir})
 		url, err := pluginIndex.GetPluginSourceURL("elixir")
 		assert.Nil(t, err)
 		assert.Equal(t, url, elixirPluginURL)
@@ -100,7 +109,7 @@ func TestGetPluginSourceURL(t *testing.T) {
 
 	t.Run("returns a plugin url when provided name of existing plugin when loading from cache", func(t *testing.T) {
 		dir := t.TempDir()
-		pluginIndex := New(dir, realIndexURL, false, 10, &MockIndex{Directory: dir})
+		pluginIndex := New(dir, mockIndexURL, false, 10, &MockIndex{Directory: dir})
 		url, err := pluginIndex.GetPluginSourceURL("elixir")
 		assert.Nil(t, err)
 		assert.Equal(t, url, elixirPluginURL)
@@ -112,7 +121,7 @@ func TestGetPluginSourceURL(t *testing.T) {
 
 	t.Run("returns an error when given a name that isn't in the index", func(t *testing.T) {
 		dir := t.TempDir()
-		pluginIndex := New(dir, realIndexURL, false, 10, &MockIndex{Directory: dir})
+		pluginIndex := New(dir, mockIndexURL, false, 10, &MockIndex{Directory: dir})
 		url, err := pluginIndex.GetPluginSourceURL("foobar")
 		assert.EqualError(t, err, "plugin foobar not found in repository")
 		assert.Equal(t, url, "")
@@ -130,7 +139,7 @@ func TestGetPluginSourceURL(t *testing.T) {
 		pluginIndex := New(dir, badIndexURL, false, 10, &repo)
 
 		url, err := pluginIndex.GetPluginSourceURL("lua")
-		assert.EqualError(t, err, "unable to clone: repository not found")
+		assert.EqualError(t, err, "unable to update plugin index: unable to clone: repository not found")
 		assert.Equal(t, url, "")
 	})
 
@@ -138,7 +147,7 @@ func TestGetPluginSourceURL(t *testing.T) {
 		dir := t.TempDir()
 		pluginIndex := New(dir, badIndexURL, false, 10, &MockIndex{Directory: dir})
 		url, err := pluginIndex.GetPluginSourceURL("lua")
-		assert.EqualError(t, err, "unable to clone: repository not found")
+		assert.EqualError(t, err, "unable to initialize index: unable to clone: repository not found")
 		assert.Equal(t, url, "")
 	})
 }
@@ -146,10 +155,17 @@ func TestGetPluginSourceURL(t *testing.T) {
 func TestRefresh(t *testing.T) {
 	t.Run("with Git updates repo when called once", func(t *testing.T) {
 		dir := t.TempDir()
-		pluginIndex := New(dir, realIndexURL, false, 0, &git.Repo{Directory: dir})
-		url, err := pluginIndex.GetPluginSourceURL("elixir")
+		indexDir := filepath.Join(dir, "index")
+		err := os.Mkdir(indexDir, 0o777)
 		assert.Nil(t, err)
-		assert.Equal(t, url, elixirPluginURL)
+
+		repoPath, err := repotest.GeneratePluginIndex(dir)
+		assert.Nil(t, err)
+
+		pluginIndex := New(indexDir, repoPath, false, 0, &git.Repo{Directory: indexDir})
+		url, err := pluginIndex.GetPluginSourceURL("foo")
+		assert.Nil(t, err)
+		assert.Equal(t, url, fooPluginURL)
 
 		updated, err := pluginIndex.Refresh()
 		assert.Nil(t, err)
@@ -158,7 +174,7 @@ func TestRefresh(t *testing.T) {
 
 	t.Run("updates repo when called once", func(t *testing.T) {
 		dir := t.TempDir()
-		pluginIndex := New(dir, realIndexURL, false, 0, &MockIndex{Directory: dir})
+		pluginIndex := New(dir, mockIndexURL, false, 0, &MockIndex{Directory: dir})
 
 		updated, err := pluginIndex.Refresh()
 		assert.Nil(t, err)
@@ -171,7 +187,7 @@ func TestRefresh(t *testing.T) {
 
 	t.Run("does not update index when time has not elaspsed", func(t *testing.T) {
 		dir := t.TempDir()
-		pluginIndex := New(dir, realIndexURL, false, 10, &MockIndex{Directory: dir})
+		pluginIndex := New(dir, mockIndexURL, false, 10, &MockIndex{Directory: dir})
 
 		// Call Refresh twice, the second call should not perform an update
 		updated, err := pluginIndex.Refresh()
@@ -185,7 +201,7 @@ func TestRefresh(t *testing.T) {
 
 	t.Run("updates plugin index when time has elaspsed", func(t *testing.T) {
 		dir := t.TempDir()
-		pluginIndex := New(dir, realIndexURL, false, 0, &MockIndex{Directory: dir})
+		pluginIndex := New(dir, mockIndexURL, false, 0, &MockIndex{Directory: dir})
 
 		// Call Refresh twice, the second call should perform an update
 		updated, err := pluginIndex.Refresh()
@@ -200,10 +216,10 @@ func TestRefresh(t *testing.T) {
 
 	t.Run("returns error when plugin index repo doesn't exist", func(t *testing.T) {
 		dir := t.TempDir()
-		pluginIndex := New(dir, badIndexURL, false, 0, &MockIndex{Directory: dir})
 
+		pluginIndex := New(dir, badIndexURL, false, 0, &MockIndex{Directory: dir})
 		updated, err := pluginIndex.Refresh()
-		assert.EqualError(t, err, "unable to clone: repository not found")
+		assert.EqualError(t, err, "unable to initialize index: unable to clone: repository not found")
 		assert.False(t, updated)
 	})
 }

plugins/plugins_test.go

@@ -1,28 +1,23 @@
 package plugins
 
 import (
-	"fmt"
 	"os"
-	"os/exec"
 	"path/filepath"
 	"strings"
 	"testing"
 
 	"asdf/config"
+	"asdf/repotest"
 
 	"github.com/stretchr/testify/assert"
 )
 
-// TODO: Switch to local repo so tests don't go over the network
-const (
-	testRepo       = "https://github.com/Stratus3D/asdf-lua"
-	testPluginName = "lua"
-)
+const testPluginName = "lua"
 
 func TestList(t *testing.T) {
 	testDataDir := t.TempDir()
 	conf := config.Config{DataDir: testDataDir}
-	testRepo, err := installMockPluginRepo(testDataDir, testPluginName)
+	testRepo, err := repotest.GeneratePlugin("dummy_plugin", testDataDir, testPluginName)
 	assert.Nil(t, err)
 
 	err = Add(conf, testPluginName, testRepo)
@@ -93,7 +88,7 @@ func TestAdd(t *testing.T) {
 
 		for _, invalid := range invalids {
 			t.Run(invalid, func(t *testing.T) {
-				err := Add(config.Config{}, invalid, testRepo)
+				err := Add(config.Config{}, invalid, "never-cloned")
 
 				expectedErrMsg := "is invalid. Name may only contain lowercase letters, numbers, '_', and '-'"
 				if !strings.Contains(err.Error(), expectedErrMsg) {
@@ -107,13 +102,16 @@ func TestAdd(t *testing.T) {
 		conf := config.Config{DataDir: testDataDir}
 
 		// Add plugin
-		err := Add(conf, testPluginName, testRepo)
+		repoPath, err := repotest.GeneratePlugin("dummy_plugin", testDataDir, testPluginName)
+		assert.Nil(t, err)
+
+		err = Add(conf, testPluginName, repoPath)
 		if err != nil {
 			t.Fatal("Expected to be able to add plugin")
 		}
 
 		// Add it again to trigger error
-		err = Add(conf, testPluginName, testRepo)
+		err = Add(conf, testPluginName, repoPath)
 
 		if err == nil {
 			t.Fatal("expected error got nil")
@@ -136,8 +134,10 @@ func TestAdd(t *testing.T) {
 	t.Run("when plugin name and URL are valid installs plugin", func(t *testing.T) {
 		testDataDir := t.TempDir()
 		conf := config.Config{DataDir: testDataDir}
+		pluginPath, err := repotest.GeneratePlugin("dummy_plugin", testDataDir, testPluginName)
+		assert.Nil(t, err)
 
-		err := Add(conf, testPluginName, testRepo)
+		err = Add(conf, testPluginName, pluginPath)
 
 		assert.Nil(t, err, "Expected to be able to add plugin")
 
@@ -149,14 +149,17 @@ func TestAdd(t *testing.T) {
 
 		entries, err := os.ReadDir(pluginDir + "/bin")
 		assert.Nil(t, err)
-		assert.Equal(t, 5, len(entries))
+		assert.Equal(t, 12, len(entries))
 	})
 
 	t.Run("when parameters are valid creates plugin download dir", func(t *testing.T) {
 		testDataDir := t.TempDir()
 		conf := config.Config{DataDir: testDataDir}
 
-		err := Add(conf, testPluginName, testRepo)
+		repoPath, err := repotest.GeneratePlugin("dummy_plugin", testDataDir, testPluginName)
+		assert.Nil(t, err)
+
+		err = Add(conf, testPluginName, repoPath)
 		assert.Nil(t, err)
 
 		// Assert download dir exists
@@ -170,7 +173,10 @@ func TestRemove(t *testing.T) {
 	testDataDir := t.TempDir()
 	conf := config.Config{DataDir: testDataDir}
 
-	err := Add(conf, testPluginName, testRepo)
+	repoPath, err := repotest.GeneratePlugin("dummy_plugin", testDataDir, testPluginName)
+	assert.Nil(t, err)
+
+	err = Add(conf, testPluginName, repoPath)
 	assert.Nil(t, err)
 
 	t.Run("returns error when plugin with name does not exist", func(t *testing.T) {
@@ -197,7 +203,7 @@ func TestRemove(t *testing.T) {
 	})
 
 	t.Run("removes plugin download dir when passed name of installed plugin", func(t *testing.T) {
-		err := Add(conf, testPluginName, testRepo)
+		err := Add(conf, testPluginName, repoPath)
 		assert.Nil(t, err)
 
 		err = Remove(conf, testPluginName)
@@ -214,7 +220,10 @@ func TestUpdate(t *testing.T) {
 	testDataDir := t.TempDir()
 	conf := config.Config{DataDir: testDataDir}
 
-	err := Add(conf, testPluginName, testRepo)
+	repoPath, err := repotest.GeneratePlugin("dummy_plugin", testDataDir, testPluginName)
+	assert.Nil(t, err)
+
+	err = Add(conf, testPluginName, repoPath)
 	assert.Nil(t, err)
 
 	badPluginName := "badplugin"
@@ -359,7 +368,7 @@ func TestRunCallback(t *testing.T) {
 
 	testDataDir := t.TempDir()
 	conf := config.Config{DataDir: testDataDir}
-	testRepo, err := installMockPluginRepo(testDataDir, testPluginName)
+	testRepo, err := repotest.GeneratePlugin("dummy_plugin", testDataDir, testPluginName)
 	assert.Nil(t, err)
 
 	err = Add(conf, testPluginName, testRepo)
@@ -412,125 +421,3 @@ func touchFile(name string) error {
 	}
 	return file.Close()
 }
-
-func installMockPluginRepo(dataDir, name string) (string, error) {
-	// Because the legacy dummy plugin directory is relative to the root of this
-	// project I cannot use the usual testing functions to locate it. To
-	// determine the location of it we compute the module root, which also
-	// happens to be the root of the repo.
-	modRootDir, err := moduleRoot()
-	if err != nil {
-		return "", err
-	}
-
-	location := dataDir + "/repo-" + name
-
-	// Then we specify the path to the dummy plugin relative to the module root
-	err = runCmd("cp", "-r", filepath.Join(modRootDir, "test/fixtures/dummy_plugin"), location)
-	if err != nil {
-		return location, err
-	}
-
-	// Definitely some opportunities to refactor here. This code might be
-	// simplified by switching to the Go git library
-	err = runCmd("git", "-C", location, "init", "-q")
-	if err != nil {
-		return location, err
-	}
-
-	err = runCmd("git", "-C", location, "config", "user.name", "\"Test\"")
-	if err != nil {
-		return location, err
-	}
-
-	err = runCmd("git", "-C", location, "config", "user.email", "\"test@example.com\"")
-	if err != nil {
-		return location, err
-	}
-
-	err = runCmd("git", "-C", location, "add", "-A")
-	if err != nil {
-		return location, err
-	}
-
-	err = runCmd("git", "-C", location, "commit", "-q", "-m", fmt.Sprintf("\"asdf %s plugin init\"", name))
-	if err != nil {
-		return location, err
-	}
-
-	err = runCmd("touch", filepath.Join(location, "README.md"))
-	if err != nil {
-		return location, err
-	}
-
-	err = runCmd("git", "-C", location, "add", "-A")
-	if err != nil {
-		return location, err
-	}
-
-	err = runCmd("git", "-C", location, "commit", "-q", "-m", fmt.Sprintf("\"asdf %s plugin readme \"", name))
-	if err != nil {
-		return location, err
-	}
-
-	// kind of ugly but I want a remote with a valid path so I use the same
-	// location as the remote. Probably should refactor
-	err = runCmd("git", "-C", location, "remote", "add", "origin", location)
-	if err != nil {
-		return location, err
-	}
-
-	return location, err
-}
-
-func moduleRoot() (string, error) {
-	currentDir, err := os.Getwd()
-	if err != nil {
-		return "", err
-	}
-
-	return findModuleRoot(currentDir), nil
-}
-
-// Taken from https://github.com/golang/go/blob/9e3b1d53a012e98cfd02de2de8b1bd53522464d4/src/cmd/go/internal/modload/init.go#L1504C1-L1522C2 because that function is in an internal module
-// and I can't rely on it.
-func findModuleRoot(dir string) (roots string) {
-	if dir == "" {
-		panic("dir not set")
-	}
-	dir = filepath.Clean(dir)
-
-	// Look for enclosing go.mod.
-	for {
-		if fi, err := os.Stat(filepath.Join(dir, "go.mod")); err == nil && !fi.IsDir() {
-			return dir
-		}
-		d := filepath.Dir(dir)
-		if d == dir {
-			break
-		}
-		dir = d
-	}
-	return ""
-}
-
-// helper function to make running commands easier
-func runCmd(cmdName string, args ...string) error {
-	cmd := exec.Command(cmdName, args...)
-
-	// Capture stdout and stderr
-	var stdout strings.Builder
-	var stderr strings.Builder
-	cmd.Stdout = &stdout
-	cmd.Stderr = &stderr
-
-	err := cmd.Run()
-	if err != nil {
-		// If command fails print both stderr and stdout
-		fmt.Println("stdout:", stdout.String())
-		fmt.Println("stderr:", stderr.String())
-		return err
-	}
-
-	return nil
-}

repotest/repotest.go

@@ -0,0 +1,200 @@
+// Package repotest contains various test helpers for tests that work with code
+// relying on plugin Git repos and the asdf plugin index
+//
+// Three main actions:
+//
+// * Install plugin index repo into asdf (index contains records that point to
+// local plugins defined by this package)
+// * Install plugin into asdf data dir
+// * Create local plugin repo that can be cloned into asdf
+package repotest
+
+import (
+	"fmt"
+	"os"
+	"os/exec"
+	"path/filepath"
+	"strings"
+
+	cp "github.com/otiai10/copy"
+)
+
+const fixturesDir = "fixtures"
+
+// Setup copies all files into place and initializes all repos for any Go test
+// that needs either plugin repos or the plugin index repo.
+func Setup(asdfDataDir string) error {
+	if err := InstallPluginIndex(asdfDataDir); err != nil {
+		return err
+	}
+
+	return nil
+}
+
+// GeneratePlugin copies in the specified plugin fixture into a test directory
+// and initializes a Git repo for it so it can be installed by asdf.
+func GeneratePlugin(fixtureName, asdfDataDir, pluginName string) (string, error) {
+	root, err := getModuleRoot()
+	if err != nil {
+		return "", err
+	}
+
+	fixturesDir := filepath.Join(asdfDataDir, fixturesDir)
+	return generatePluginInDir(root, fixtureName, fixturesDir, pluginName)
+}
+
+// InstallPluginIndex generates and installs a plugin index Git repo inside of
+// the provided asdf data directory.
+func InstallPluginIndex(asdfDataDir string) error {
+	root, err := getModuleRoot()
+	if err != nil {
+		return err
+	}
+
+	// Copy in plugin index
+	source := filepath.Join(root, "test/fixtures/dummy_plugins_repo")
+	return cp.Copy(source, filepath.Join(asdfDataDir, "plugin-index"))
+}
+
+// GeneratePluginIndex generates a mock plugin index Git repo inside the given
+// directory.
+func GeneratePluginIndex(asdfDataDir string) (string, error) {
+	root, err := getModuleRoot()
+	if err != nil {
+		return "", err
+	}
+
+	// Copy in plugin index
+	source := filepath.Join(root, "test/fixtures/dummy_plugins_repo")
+	destination := filepath.Join(asdfDataDir, fixturesDir, "plugin-index")
+	err = cp.Copy(source, destination)
+	if err != nil {
+		return destination, fmt.Errorf("unable to copy in plugin index: %w", err)
+	}
+
+	// Generate git repo for plugin
+	return createGitRepo(destination)
+}
+
+func generatePluginInDir(root, fixtureName, outputDir, pluginName string) (string, error) {
+	// Copy in plugin files into output dir
+	pluginPath, err := copyInPlugin(root, fixtureName, outputDir, pluginName)
+	if err != nil {
+		return pluginPath, fmt.Errorf("unable to copy in plugin files: %w", err)
+	}
+
+	// Generate git repo for plugin
+	return createGitRepo(pluginPath)
+}
+
+func getModuleRoot() (string, error) {
+	cwd, err := os.Getwd()
+	if err != nil {
+		return "", fmt.Errorf("unable to get current working directory: %w", err)
+	}
+
+	root := findModuleRoot(cwd)
+	return root, nil
+}
+
+func createGitRepo(location string) (string, error) {
+	// Definitely some opportunities to refactor here. This code might be
+	// simplified by switching to the Go git library
+	err := runCmd("git", "-C", location, "init", "-q")
+	if err != nil {
+		return location, err
+	}
+
+	err = runCmd("git", "-C", location, "config", "user.name", "\"Test\"")
+	if err != nil {
+		return location, err
+	}
+
+	err = runCmd("git", "-C", location, "config", "user.email", "\"test@example.com\"")
+	if err != nil {
+		return location, err
+	}
+
+	err = runCmd("git", "-C", location, "add", "-A")
+	if err != nil {
+		return location, err
+	}
+
+	err = runCmd("git", "-C", location, "commit", "-q", "-m", "init repo")
+	if err != nil {
+		return location, err
+	}
+
+	err = runCmd("touch", filepath.Join(location, "README.md"))
+	if err != nil {
+		return location, err
+	}
+
+	err = runCmd("git", "-C", location, "add", "-A")
+	if err != nil {
+		return location, err
+	}
+
+	err = runCmd("git", "-C", location, "commit", "-q", "-m", "add readme")
+	if err != nil {
+		return location, err
+	}
+
+	// kind of ugly but I want a remote with a valid path so I use the same
+	// location as the remote. Probably should refactor
+	err = runCmd("git", "-C", location, "remote", "add", "origin", location)
+	if err != nil {
+		return location, err
+	}
+
+	return location, err
+}
+
+func copyInPlugin(root, name, destination, newName string) (string, error) {
+	source := filepath.Join(root, "test/fixtures/", name)
+	dest := filepath.Join(destination, newName)
+	return dest, cp.Copy(source, dest)
+}
+
+// Taken from https://github.com/golang/go/blob/9e3b1d53a012e98cfd02de2de8b1bd53522464d4/src/cmd/go/internal/modload/init.go#L1504C1-L1522C2 because that function is in an internal module
+// and I can't rely on it.
+func findModuleRoot(dir string) (roots string) {
+	if dir == "" {
+		panic("dir not set")
+	}
+	dir = filepath.Clean(dir)
+
+	// Look for enclosing go.mod.
+	for {
+		if fi, err := os.Stat(filepath.Join(dir, "go.mod")); err == nil && !fi.IsDir() {
+			return dir
+		}
+		d := filepath.Dir(dir)
+		if d == dir {
+			break
+		}
+		dir = d
+	}
+	return ""
+}
+
+// helper function to make running commands easier
+func runCmd(cmdName string, args ...string) error {
+	cmd := exec.Command(cmdName, args...)
+
+	// Capture stdout and stderr
+	var stdout strings.Builder
+	var stderr strings.Builder
+	cmd.Stdout = &stdout
+	cmd.Stderr = &stderr
+
+	err := cmd.Run()
+	if err != nil {
+		// If command fails print both stderr and stdout
+		fmt.Println("stdout:", stdout.String())
+		fmt.Println("stderr:", stderr.String())
+		return err
+	}
+
+	return nil
+}