add init getPlugin test

add a mock plugin getter, and test that we can fetch requested version
of the plugins.

command/init_test.go

@@ -534,6 +534,90 @@ func TestInit_inputFalse(t *testing.T) {
 	}
 }
 
+func TestInit_getProvider(t *testing.T) {
+	// Create a temporary working directory that is empty
+	td := tempDir(t)
+	copy.CopyDir(testFixturePath("init-get-providers"), td)
+	defer os.RemoveAll(td)
+	defer testChdir(t, td)()
+
+	getter := &mockGetProvider{
+		Providers: map[string][]string{
+			// looking for an exact version
+			"exact": []string{"1.2.3"},
+			// config requires >= 2.3.3
+			"greater_than": []string{"2.3.4", "2.3.3", "2.3.0"},
+			// config specifies
+			"between": []string{"3.4.5", "2.3.4", "1.2.3"},
+		},
+	}
+
+	ui := new(cli.MockUi)
+	c := &InitCommand{
+		Meta: Meta{
+			testingOverrides: metaOverridesForProvider(testProvider()),
+			Ui:               ui,
+		},
+		getProvider: getter.GetProvider,
+	}
+
+	args := []string{}
+	if code := c.Run(args); code != 0 {
+		t.Fatalf("bad: \n%s", ui.ErrorWriter.String())
+	}
+
+	// check that we got the providers for our config
+	exactPath := filepath.Join(c.pluginDir(), getter.FileName("exact", "1.2.3"))
+	if _, err := os.Stat(exactPath); os.IsNotExist(err) {
+		t.Fatal("provider 'exact' not downloaded")
+	}
+	greaterThanPath := filepath.Join(c.pluginDir(), getter.FileName("greater_than", "2.3.4"))
+	if _, err := os.Stat(greaterThanPath); os.IsNotExist(err) {
+		t.Fatal("provider 'greater_than' not downloaded")
+	}
+	betweenPath := filepath.Join(c.pluginDir(), getter.FileName("between", "2.3.4"))
+	if _, err := os.Stat(betweenPath); os.IsNotExist(err) {
+		t.Fatal("provider 'between' not downloaded")
+	}
+}
+
+func TestInit_getProviderMissing(t *testing.T) {
+	// Create a temporary working directory that is empty
+	td := tempDir(t)
+	copy.CopyDir(testFixturePath("init-get-providers"), td)
+	defer os.RemoveAll(td)
+	defer testChdir(t, td)()
+
+	getter := &mockGetProvider{
+		Providers: map[string][]string{
+			// looking for exact version 1.2.3
+			"exact": []string{"1.2.4"},
+			// config requires >= 2.3.3
+			"greater_than": []string{"2.3.4", "2.3.3", "2.3.0"},
+			// config specifies
+			"between": []string{"3.4.5", "2.3.4", "1.2.3"},
+		},
+	}
+
+	ui := new(cli.MockUi)
+	c := &InitCommand{
+		Meta: Meta{
+			testingOverrides: metaOverridesForProvider(testProvider()),
+			Ui:               ui,
+		},
+		getProvider: getter.GetProvider,
+	}
+
+	args := []string{}
+	if code := c.Run(args); code == 0 {
+		t.Fatalf("expceted error, got output: \n%s", ui.OutputWriter.String())
+	}
+
+	if !strings.Contains(ui.ErrorWriter.String(), "no suitable version for provider") {
+		t.Fatalf("unexpected error output: %s", ui.ErrorWriter)
+	}
+}
+
 /*
 func TestInit_remoteState(t *testing.T) {
 	tmp, cwd := testCwd(t)

command/plugins_test.go

@@ -0,0 +1,56 @@
+package command
+
+import (
+	"fmt"
+	"os"
+	"path/filepath"
+
+	"github.com/hashicorp/terraform/plugin/discovery"
+)
+
+// mockGetProvider providers a GetProvider method for testing automatic
+// provider downloads
+type mockGetProvider struct {
+	// A map of provider names to available versions.
+	// The tests expect the versions to be in order from newest to oldest.
+	Providers map[string][]string
+}
+
+func (m mockGetProvider) FileName(provider, version string) string {
+	return fmt.Sprintf("terraform-provider-%s-V%s-X4", provider, version)
+}
+
+// GetProvider will check the Providers map to see if it can find a suitable
+// version, and put an empty file in the dst directory.
+func (m mockGetProvider) GetProvider(dst, provider string, req discovery.Constraints) error {
+	versions := m.Providers[provider]
+	if len(versions) == 0 {
+		return fmt.Errorf("provider %q not found", provider)
+	}
+
+	err := os.MkdirAll(dst, 0755)
+	if err != nil {
+		return fmt.Errorf("error creating plugins directory: %s", err)
+	}
+
+	for _, v := range versions {
+		version, err := discovery.VersionStr(v).Parse()
+		if err != nil {
+			panic(err)
+		}
+
+		if req.Has(version) {
+			// provider filename
+			name := m.FileName(provider, v)
+			path := filepath.Join(dst, name)
+			f, err := os.Create(path)
+			if err != nil {
+				return fmt.Errorf("error fetching provider: %s", err)
+			}
+			f.Close()
+			return nil
+		}
+	}
+
+	return fmt.Errorf("no suitable version for provider %q found with constraints %s", provider, req)
+}

command/test-fixtures/init-get-providers/main.tf

@@ -0,0 +1,11 @@
+provider "exact" {
+	version = "1.2.3"
+}
+
+provider "greater_than" {
+	version = ">= 2.3.3"
+}
+
+provider "between" {
+	version = "> 1.0.0 , < 3.0.0"
+}