Support installing latest with EnsurePackage

Originally EnsurePackage was written for the older go get behavior. Now
that we are using go install, the required syntax is a bit different,
for example when a version is not specified, we should use @latest. I've
also made it easier for people to specify the version both with and
without the v prefix, and allow for them specifying either an empty
version or latest.

Signed-off-by: Carolyn Van Slyck <me@carolynvanslyck.com>

Author: carolynvs

pkg/install.go

@@ -64,24 +64,22 @@ func getCommandName(pkg string) string {
 // InstallPackage installs the latest version of a package.
 //
 // When version is specified, install that version. Otherwise install the most
-// recent code from the default branch.
+// recent version.
 func InstallPackage(pkg string, version string) error {
 	gopath.EnsureGopathBin()
 
 	cmd := getCommandName(pkg)
 
-	// Optionally install a specific version of the package
-	moduleVersion := ""
-	if version != "" {
-		if strings.HasPrefix(version, "v") {
-			moduleVersion = "@" + version
-		} else {
-			moduleVersion = "@v" + version
+	if version == "" {
+		version = "latest"
+	} else {
+		if version != "latest" && !strings.HasPrefix(version, "v") {
+			version = "v" + version
 		}
 	}
 
-	fmt.Printf("Installing %s%s\n", cmd, moduleVersion)
-	err := shx.Command("go", "install", pkg+moduleVersion).
+	fmt.Printf("Installing %s@%s\n", cmd, version)
+	err := shx.Command("go", "install", pkg+"@"+version).
 		Env("GO111MODULE=on").In(os.TempDir()).RunE()
 	if err != nil {
 		return err
@@ -132,10 +130,13 @@ func IsCommandAvailable(cmd string, version string, versionArgs ...string) (bool
 	}
 
 	// If no version is specified, report that it is installed
-	if version == "" {
+	if version == "" || version == "latest" {
 		return true, nil
 	}
 
+	// Trim the leading v prefix if present so that we are more likely to get a hit on the version
+	version = strings.TrimPrefix(version, "v")
+
 	// Get the installed version
 	versionOutput, err := shx.OutputE(cmd, versionArgs...)
 	if err != nil {

pkg/install_test.go

@@ -42,14 +42,30 @@ func TestGetCommandName(t *testing.T) {
 	})
 }
 
-func TestEnsurePackage_MajorVersion(t *testing.T) {
+func TestEnsurePackage(t *testing.T) {
 	os.Setenv(mg.VerboseEnv, "true")
-	err, cleanup := gopath.UseTempGopath()
-	require.NoError(t, err, "Failed to set up a temporary GOPATH")
-	defer cleanup()
+	defer os.Unsetenv(mg.VerboseEnv)
 
-	hasCmd, err := IsCommandAvailable("testpkg", "")
-	require.False(t, hasCmd)
-	err = EnsurePackage("github.com/carolynvs/testpkg/v2", "v2.0.1", "--version")
-	require.NoError(t, err)
+	testcases := []struct {
+		name    string
+		version string
+	}{
+		{name: "with prefix", version: "v2.0.1"},
+		{name: "without prefix", version: "2.0.1"},
+		{name: "no version", version: ""},
+		{name: "latest version", version: "latest"},
+	}
+
+	for _, tc := range testcases {
+		t.Run(tc.name, func(t *testing.T) {
+			err, cleanup := gopath.UseTempGopath()
+			require.NoError(t, err, "Failed to set up a temporary GOPATH")
+			defer cleanup()
+
+			hasCmd, err := IsCommandAvailable("testpkg", "")
+			require.False(t, hasCmd)
+			err = EnsurePackage("github.com/carolynvs/testpkg/v2", tc.version, "--version")
+			require.NoError(t, err)
+		})
+	}
 }

shx/prepared_command_test.go

@@ -38,8 +38,8 @@ func TestPreparedCommand_Run_Fail(t *testing.T) {
 		t.Fatal("expected shx.Command to fail")
 	}
 
-	wantStderr := "go run: no go files listed\n"
-	assert.Equal(t, wantStderr, gotStderr)
+	wantStderr := "no go files listed"
+	assert.Contains(t, gotStderr, wantStderr)
 }
 
 func TestPreparedCommand_Run_Verbose(t *testing.T) {
@@ -91,8 +91,8 @@ func TestPreparedCommand_RunE_Fail(t *testing.T) {
 		t.Fatal("expected the shx.Command to fail")
 	}
 
-	wantStderr := "go run: no go files listed\n"
-	assert.Equal(t, wantStderr, gotStderr)
+	wantStderr := "no go files listed"
+	assert.Contains(t, gotStderr, wantStderr)
 }
 
 func TestPreparedCommand_RunE_Verbose(t *testing.T) {
@@ -217,8 +217,8 @@ func TestPreparedCommand_Output_Fail(t *testing.T) {
 		t.Fatal("expected shx.Command to fail")
 	}
 
-	wantStderr := "go run: no go files listed\n"
-	assert.Equal(t, wantStderr, gotStderr)
+	wantStderr := "no go files listed"
+	assert.Contains(t, gotStderr, wantStderr)
 	assert.Empty(t, gotOutput)
 }
 
@@ -276,8 +276,8 @@ func TestPreparedCommand_OutputE_Fail(t *testing.T) {
 		t.Fatal("expected the shx.Command to fail")
 	}
 
-	wantStderr := "go run: no go files listed\n"
-	assert.Equal(t, wantStderr, gotStderr)
+	wantStderr := "no go files listed"
+	assert.Contains(t, gotStderr, wantStderr)
 	assert.Empty(t, gotOutput)
 }