Merge pull request #18 from stream-aha/arbitrary-tag

allow fetch to work with arbitrary tag formats

main.go

@@ -106,14 +106,18 @@ func runFetch (c *cli.Context) error {
 		}
 	}
 
-	// Find the specific release that matches the latest version constraint
-	latestTag, err := getLatestAcceptableTag(options.TagConstraint, tags)
-	if err != nil {
-		if err.errorCode == INVALID_TAG_CONSTRAINT_EXPRESSION {
-			return errors.New(getErrorMessage(INVALID_TAG_CONSTRAINT_EXPRESSION, err.details))
-		} else {
-			return fmt.Errorf("Error occurred while computing latest tag that satisfies version contraint expression: %s", err)
+	specific, desiredTag := isTagConstraintSpecificTag(options.TagConstraint)
+	if !specific {
+		// Find the specific release that matches the latest version constraint
+		latestTag, err := getLatestAcceptableTag(options.TagConstraint, tags)
+		if err != nil {
+			if err.errorCode == INVALID_TAG_CONSTRAINT_EXPRESSION {
+				return errors.New(getErrorMessage(INVALID_TAG_CONSTRAINT_EXPRESSION, err.details))
+			} else {
+				return fmt.Errorf("Error occurred while computing latest tag that satisfies version contraint expression: %s", err)
+			}
 		}
+		desiredTag = latestTag
 	}
 
 	// Prepare the vars we'll need to download
@@ -129,12 +133,12 @@ func runFetch (c *cli.Context) error {
 	}
 
 	// Download any requested source files
-	if err := downloadSourcePaths(options.SourcePaths, options.LocalDownloadPath, repo, latestTag, options.BranchName, options.CommitSha); err != nil {
+	if err := downloadSourcePaths(options.SourcePaths, options.LocalDownloadPath, repo, desiredTag, options.BranchName, options.CommitSha); err != nil {
 		return err
 	}
 
 	// Download any requested release assets
-	if err := downloadReleaseAssets(options.ReleaseAssets, options.LocalDownloadPath, repo, latestTag); err != nil {
+	if err := downloadReleaseAssets(options.ReleaseAssets, options.LocalDownloadPath, repo, desiredTag); err != nil {
 		return err
 	}
 

tag.go

@@ -7,6 +7,25 @@ import (
 	"github.com/hashicorp/go-version"
 )
 
+func isTagConstraintSpecificTag(tagConstraint string) (bool, string) {
+	if len(tagConstraint) > 0 {
+		switch tagConstraint[0] {
+		// Check for a tagConstraint '='
+		case '=':
+			return true, strings.TrimSpace(tagConstraint[1:])
+
+		// Check for a tagConstraint without constraint specifier
+		// Neither of '!=', '>', '>=', '<', '<=', '~>' is prefixed before tag
+		case '>', '<', '!', '~':
+			return false, tagConstraint
+
+		default:
+			return true, strings.TrimSpace(tagConstraint)
+		}
+	}
+	return false, tagConstraint
+}
+
 func getLatestAcceptableTag(tagConstraint string, tags []string) (string, *FetchError) {
 	var latestTag string
 

tag_test.go

@@ -41,6 +41,42 @@ func TestGetLatestAcceptableTag(t *testing.T) {
 	}
 }
 
+func TestIsTagConstraintSpecificTag(t *testing.T) {
+	t.Parallel()
+
+	cases := []struct {
+		tagConstraint string
+		desiredTag    string
+		specific      bool
+	}{
+		{"1.0.7", "1.0.7", true},
+		{" 1.0.7	 ", "1.0.7", true},
+		{"=1.0.7", "1.0.7", true},
+		{"= 1.0.7", "1.0.7", true},
+
+		{"~> 1.0.0", "~> 1.0.0", false},
+		{"> 1.3", "> 1.3", false},
+		{">= 1.3", ">= 1.3", false},
+		{"<= 1.3", "<= 1.3", false},
+		{"< 1.3", "< 1.3", false},
+
+		{"v1.0.7", "v1.0.7", true},
+		{" v1.0.7	 ", "v1.0.7", true},
+		{"=v1.0.7", "v1.0.7", true},
+		{"= v1.0.7", "v1.0.7", true},
+	}
+
+	for _, tc := range cases {
+		specific, desiredTag := isTagConstraintSpecificTag(tc.tagConstraint)
+		if specific != tc.specific {
+			t.Fatalf("Given constraint: \"%s\", expected %t, but received %t", tc.tagConstraint, tc.specific, specific)
+		}
+		if desiredTag != tc.desiredTag {
+			t.Fatalf("Given constraint: \"%s\", expected result tag: \"%s\", but received \"%s\"", tc.tagConstraint, tc.desiredTag, desiredTag)
+		}
+	}
+}
+
 func TestGetLatestAcceptableTagOnEmptyConstraint(t *testing.T) {
 	t.Parallel()