fs.Version to support version constrained binary discovery

README.md

@@ -31,7 +31,7 @@ The `Installer` offers a few high-level methods:
 The `Installer` methods accept number of different `Source` types.
 Each comes with different trade-offs described below.
 
- - `fs.{AnyVersion,ExactVersion}` - Finds a binary in `$PATH` (or additional paths)
+ - `fs.{AnyVersion,ExactVersion,Version}` - Finds a binary in `$PATH` (or additional paths)
    - **Pros:**
      - This is most convenient when you already have the product installed on your system
       which you already manage.

fs/fs_test.go

@@ -16,6 +16,9 @@ var (
 
 	_ src.Findable       = &ExactVersion{}
 	_ src.LoggerSettable = &ExactVersion{}
+
+	_ src.Findable       = &Version{}
+	_ src.LoggerSettable = &Version{}
 )
 
 func TestExactVersion(t *testing.T) {
@@ -36,3 +39,22 @@ func TestExactVersion(t *testing.T) {
 		t.Fatal(err)
 	}
 }
+
+func TestVersion(t *testing.T) {
+	t.Skip("TODO")
+	testutil.EndToEndTest(t)
+
+	// TODO: mock out command execution?
+
+	t.Setenv("PATH", "")
+
+	v := &Version{
+		Product:     product.Terraform,
+		Constraints: version.MustConstraints(version.NewConstraint(">= 1.0")),
+	}
+	v.SetLogger(testutil.TestLogger())
+	_, err := v.Find(context.Background())
+	if err != nil {
+		t.Fatal(err)
+	}
+}

fs/version.go

@@ -0,0 +1,97 @@
+package fs
+
+import (
+	"context"
+	"fmt"
+	"log"
+	"path/filepath"
+	"time"
+
+	"github.com/hashicorp/go-version"
+	"github.com/hashicorp/hc-install/errors"
+	"github.com/hashicorp/hc-install/internal/src"
+	"github.com/hashicorp/hc-install/internal/validators"
+	"github.com/hashicorp/hc-install/product"
+)
+
+// Version finds the first executable binary of the product name
+// which matches the version constraint within system $PATH and any declared ExtraPaths
+// (which are *appended* to any directories in $PATH)
+type Version struct {
+	Product     product.Product
+	Constraints version.Constraints
+	ExtraPaths  []string
+	Timeout     time.Duration
+
+	logger *log.Logger
+}
+
+func (*Version) IsSourceImpl() src.InstallSrcSigil {
+	return src.InstallSrcSigil{}
+}
+
+func (v *Version) SetLogger(logger *log.Logger) {
+	v.logger = logger
+}
+
+func (v *Version) log() *log.Logger {
+	if v.logger == nil {
+		return discardLogger
+	}
+	return v.logger
+}
+
+func (v *Version) Validate() error {
+	if !validators.IsBinaryNameValid(v.Product.BinaryName()) {
+		return fmt.Errorf("invalid binary name: %q", v.Product.BinaryName())
+	}
+	if len(v.Constraints) == 0 {
+		return fmt.Errorf("undeclared version constraints")
+	}
+	if v.Product.GetVersion == nil {
+		return fmt.Errorf("undeclared version getter")
+	}
+	return nil
+}
+
+func (v *Version) Find(ctx context.Context) (string, error) {
+	timeout := defaultTimeout
+	if v.Timeout > 0 {
+		timeout = v.Timeout
+	}
+	ctx, cancelFunc := context.WithTimeout(ctx, timeout)
+	defer cancelFunc()
+
+	execPath, err := findFile(lookupDirs(v.ExtraPaths), v.Product.BinaryName(), func(file string) error {
+		err := checkExecutable(file)
+		if err != nil {
+			return err
+		}
+
+		ver, err := v.Product.GetVersion(ctx, file)
+		if err != nil {
+			return err
+		}
+
+		for _, vc := range v.Constraints {
+			if !vc.Check(ver) {
+				return fmt.Errorf("version (%s) doesn't meet constraints %s", ver, vc.String())
+			}
+		}
+
+		return nil
+	})
+	if err != nil {
+		return "", errors.SkippableErr(err)
+	}
+
+	if !filepath.IsAbs(execPath) {
+		var err error
+		execPath, err = filepath.Abs(execPath)
+		if err != nil {
+			return "", errors.SkippableErr(err)
+		}
+	}
+
+	return execPath, nil
+}

fs/version_test.go

@@ -0,0 +1,70 @@
+package fs
+
+import (
+	"fmt"
+	"testing"
+
+	"github.com/hashicorp/go-version"
+	"github.com/hashicorp/hc-install/product"
+)
+
+func TestVersionValidate(t *testing.T) {
+	t.Parallel()
+
+	testCases := map[string]struct {
+		v           Version
+		expectedErr error
+	}{
+		"Product-incorrect-binary-name": {
+			v: Version{
+				Product: product.Product{
+					BinaryName: func() string { return "invalid!" },
+				},
+			},
+			expectedErr: fmt.Errorf("invalid binary name: \"invalid!\""),
+		},
+		"Product-missing-get-version": {
+			v: Version{
+				Product: product.Product{
+					BinaryName: product.Terraform.BinaryName,
+				},
+				Constraints: version.MustConstraints(version.NewConstraint(">= 1.0")),
+			},
+			expectedErr: fmt.Errorf("undeclared version getter"),
+		},
+		"Product-missing-version-constraint": {
+			v: Version{
+				Product: product.Terraform,
+			},
+			expectedErr: fmt.Errorf("undeclared version constraints"),
+		},
+		"Product-and-version-constraint": {
+			v: Version{
+				Product:     product.Terraform,
+				Constraints: version.MustConstraints(version.NewConstraint(">= 1.0")),
+			},
+		},
+	}
+
+	for name, testCase := range testCases {
+		name, testCase := name, testCase
+
+		t.Run(name, func(t *testing.T) {
+			t.Parallel()
+
+			err := testCase.v.Validate()
+
+			if err == nil && testCase.expectedErr != nil {
+				t.Fatalf("expected error: %s, got no error", testCase.expectedErr)
+			}
+
+			if err != nil && testCase.expectedErr == nil {
+				t.Fatalf("expected no error, got error: %s", err)
+			}
+
+			if err != nil && testCase.expectedErr != nil && err.Error() != testCase.expectedErr.Error() {
+				t.Fatalf("expected error: %s, got error: %s", testCase.expectedErr, err)
+			}
+		})
+	}
+}