[StorePathParts] move to nix package (#1722)

## Summary

This should be in the `nix` package

Seeking to reduce the code in #1692.

## How was it tested?

compiles, and tests should pass

Author: savil

internal/devpkg/narinfo_cache.go

@@ -4,10 +4,8 @@ import (
 	"context"
 	"io"
 	"net/http"
-	"strings"
 	"sync"
 	"time"
-	"unicode"
 
 	"github.com/pkg/errors"
 	"go.jetpack.io/devbox/internal/boxcli/featureflag"
@@ -110,8 +108,8 @@ func (p *Package) fetchNarInfoStatus() (bool, error) {
 		)
 	}
 
-	pathParts := newStorePathParts(sysInfo.StorePath)
-	reqURL := BinaryCache + "/" + pathParts.hash + ".narinfo"
+	pathParts := nix.NewStorePathParts(sysInfo.StorePath)
+	reqURL := BinaryCache + "/" + pathParts.Hash + ".narinfo"
 	ctx, cancel := context.WithTimeout(context.Background(), 5*time.Second)
 	defer cancel()
 	req, err := http.NewRequestWithContext(ctx, http.MethodHead, reqURL, nil)
@@ -181,35 +179,3 @@ func (p *Package) sysInfoIfExists() (*lock.SystemInfo, error) {
 	}
 	return sysInfo, nil
 }
-
-// storePath are the constituent parts of
-// /nix/store/<hash>-<name>-<version>
-//
-// This is a helper struct for analyzing the string representation
-type storePathParts struct {
-	hash    string
-	name    string
-	version string
-}
-
-// newStorePathParts splits a Nix store path into its hash, name and version
-// components in the same way that Nix does.
-//
-// See https://nixos.org/manual/nix/stable/language/builtins.html#builtins-parseDrvName
-func newStorePathParts(path string) storePathParts {
-	path = strings.TrimPrefix(path, "/nix/store/")
-	// path is now <hash>-<name>-<version
-
-	hash, name := path[:32], path[33:]
-	dashIndex := 0
-	for i, r := range name {
-		if dashIndex != 0 && !unicode.IsLetter(r) {
-			return storePathParts{hash: hash, name: name[:dashIndex], version: name[i:]}
-		}
-		dashIndex = 0
-		if r == '-' {
-			dashIndex = i
-		}
-	}
-	return storePathParts{hash: hash, name: name}
-}

internal/devpkg/package_test.go

@@ -181,49 +181,6 @@ func TestHashFromNixPkgsURL(t *testing.T) {
 	}
 }
 
-func TestStorePathParts(t *testing.T) {
-	testCases := []struct {
-		storePath string
-		expected  storePathParts
-	}{
-		// simple case:
-		{
-			storePath: "/nix/store/cvrn84c1hshv2wcds7n1rhydi6lacqns-gnumake-4.4.1",
-			expected: storePathParts{
-				hash:    "cvrn84c1hshv2wcds7n1rhydi6lacqns",
-				name:    "gnumake",
-				version: "4.4.1",
-			},
-		},
-		// the package name can have dashes:
-		{
-			storePath: "/nix/store/q2xdxsswjqmqcbax81pmazm367s7jzyb-cctools-binutils-darwin-wrapper-973.0.1",
-			expected: storePathParts{
-				hash:    "q2xdxsswjqmqcbax81pmazm367s7jzyb",
-				name:    "cctools-binutils-darwin-wrapper",
-				version: "973.0.1",
-			},
-		},
-		// version is optional. This is an artificial example I constructed
-		{
-			storePath: "/nix/store/gfxwrd5nggc68pjj3g3jhlldim9rpg0p-coreutils",
-			expected: storePathParts{
-				hash: "gfxwrd5nggc68pjj3g3jhlldim9rpg0p",
-				name: "coreutils",
-			},
-		},
-	}
-
-	for _, testCase := range testCases {
-		t.Run(testCase.storePath, func(t *testing.T) {
-			parts := newStorePathParts(testCase.storePath)
-			if parts != testCase.expected {
-				t.Errorf("Expected %v, got %v", testCase.expected, parts)
-			}
-		})
-	}
-}
-
 func TestCanonicalName(t *testing.T) {
 	tests := []struct {
 		pkgName      string

internal/nix/storepath.go

@@ -0,0 +1,40 @@
+package nix
+
+import (
+	"strings"
+	"unicode"
+)
+
+// storePath are the constituent parts of
+// /nix/store/<hash>-<name>-<version>
+//
+// This is a helper struct for analyzing the string representation
+type StorePathParts struct {
+	Hash    string
+	Name    string
+	Version string
+}
+
+// NewStorePathParts splits a Nix store path into its hash, name and version
+// components in the same way that Nix does.
+//
+// See https://nixos.org/manual/nix/stable/language/builtins.html#builtins-parseDrvName
+//
+// TODO: store paths can also have `-{output}` suffixes, which need to be handled below.
+func NewStorePathParts(path string) StorePathParts {
+	path = strings.TrimPrefix(path, "/nix/store/")
+	// path is now <hash>-<name>-<version
+
+	hash, name := path[:32], path[33:]
+	dashIndex := 0
+	for i, r := range name {
+		if dashIndex != 0 && !unicode.IsLetter(r) {
+			return StorePathParts{Hash: hash, Name: name[:dashIndex], Version: name[i:]}
+		}
+		dashIndex = 0
+		if r == '-' {
+			dashIndex = i
+		}
+	}
+	return StorePathParts{Hash: hash, Name: name}
+}

internal/nix/storepath_test.go

@@ -0,0 +1,48 @@
+package nix
+
+import (
+	"testing"
+)
+
+func TestStorePathParts(t *testing.T) {
+	testCases := []struct {
+		storePath string
+		expected  StorePathParts
+	}{
+		// simple case:
+		{
+			storePath: "/nix/store/cvrn84c1hshv2wcds7n1rhydi6lacqns-gnumake-4.4.1",
+			expected: StorePathParts{
+				Hash:    "cvrn84c1hshv2wcds7n1rhydi6lacqns",
+				Name:    "gnumake",
+				Version: "4.4.1",
+			},
+		},
+		// the package name can have dashes:
+		{
+			storePath: "/nix/store/q2xdxsswjqmqcbax81pmazm367s7jzyb-cctools-binutils-darwin-wrapper-973.0.1",
+			expected: StorePathParts{
+				Hash:    "q2xdxsswjqmqcbax81pmazm367s7jzyb",
+				Name:    "cctools-binutils-darwin-wrapper",
+				Version: "973.0.1",
+			},
+		},
+		// version is optional. This is an artificial example I constructed
+		{
+			storePath: "/nix/store/gfxwrd5nggc68pjj3g3jhlldim9rpg0p-coreutils",
+			expected: StorePathParts{
+				Hash: "gfxwrd5nggc68pjj3g3jhlldim9rpg0p",
+				Name: "coreutils",
+			},
+		},
+	}
+
+	for _, testCase := range testCases {
+		t.Run(testCase.storePath, func(t *testing.T) {
+			parts := NewStorePathParts(testCase.storePath)
+			if parts != testCase.expected {
+				t.Errorf("Expected %v, got %v", testCase.expected, parts)
+			}
+		})
+	}
+}