diff --git a/github/locate.go b/github/locate.go
index 72ce9e6..3309818 100644
--- a/github/locate.go
+++ b/github/locate.go
@@ -5,21 +5,29 @@ import (
 	"strings"
 
 	"github.com/blang/semver"
-	"github.com/gocd-contrib/gocd-cli/utils"
 )
 
-func ResolveVersionJar(rels []Release, filterBy string, stableOnly bool) (asset *Asset, err error) {
+func ResolveVersionJar(rels []Release, filterBy string, stableOnly bool) (*Asset, error) {
 	if 0 == len(rels) {
-		return nil, nil
+		return nil, fmt.Errorf("Could not find any releases to filter")
 	}
 
 	if !stableOnly && "" == filterBy {
 		return findJarAsset(&(rels[0]))
 	} else {
-		filt := buildFilter(filterBy, !stableOnly)
-		for _, r := range rels {
-			if filt(&r) {
-				return findJarAsset(&r)
+		if filt, err := buildFilter(filterBy, !stableOnly); err != nil {
+			return nil, err
+		} else {
+			for _, r := range rels {
+				ok, e2 := filt(&r)
+
+				if e2 != nil {
+					return nil, e2
+				}
+
+				if ok {
+					return findJarAsset(&r)
+				}
 			}
 		}
 	}
@@ -27,19 +35,17 @@ func ResolveVersionJar(rels []Release, filterBy string, stableOnly bool) (asset
 	return nil, fmt.Errorf("Cannot find a release that matches version spec `%s` and stable-only=%t", filterBy, stableOnly)
 }
 
-func buildFilter(filterSpec string, allowPrerelease bool) func(*Release) bool {
+func buildFilter(filterSpec string, allowPrerelease bool) (func(*Release) (bool, error), error) {
 	if r, err := semver.ParseRange(filterSpec); err != nil {
-		utils.DieLoudly(1, "Don't know how to parse version spec `%s`: %v", filterSpec, err)
-		return nil
+		return nil, fmt.Errorf("Don't know how to parse version spec `%s`: %v", filterSpec, err)
 	} else {
-		return func(rel *Release) bool {
+		return func(rel *Release) (bool, error) {
 			if v, err := semver.Parse(rel.Version); err != nil {
-				utils.DieLoudly(1, "Cannot parse release version `%s`; does not conform to semantic version (%v)", err)
-				return false
+				return false, fmt.Errorf("Cannot parse release version `%s`; does not conform to semantic version (%v)", rel.Version, err)
 			} else {
-				return r(v) && (allowPrerelease || !rel.Prerelease)
+				return r(v) && (allowPrerelease || !rel.Prerelease), nil
 			}
-		}
+		}, nil
 	}
 }
 
diff --git a/github/locate_test.go b/github/locate_test.go
new file mode 100644
index 0000000..8d4dd60
--- /dev/null
+++ b/github/locate_test.go
@@ -0,0 +1,89 @@
+package github
+
+import (
+	"testing"
+)
+
+func jarname(version string) string {
+	return "test.name-" + version + ".jar"
+}
+
+func jarurl(version string) string {
+	return "http://test.com/releases/download/" + version + "/" + jarname(version)
+}
+
+func createRelease(version string, prerelease bool) Release {
+	return Release{Version: version, Prerelease: prerelease, Assets: []Asset{Asset{Name: jarname(version), Url: jarurl(version)}}}
+}
+
+func TestResolveVersionJar(t *testing.T) {
+	as := asserts(t)
+	releases := []Release{createRelease("1.1.1", true)}
+
+	asset, err := ResolveVersionJar(releases, "1.1.1", false)
+	as.ok(err)
+
+	as.eq(Asset{Name: jarname("1.1.1"), Url: jarurl("1.1.1")}, *asset)
+
+	asset, err = ResolveVersionJar(releases, "", false)
+	as.ok(err)
+
+	as.eq(Asset{Name: jarname("1.1.1"), Url: jarurl("1.1.1")}, *asset)
+}
+
+func TestResolveVersionJarCanSkipPreReleaseJars(t *testing.T) {
+	as := asserts(t)
+	releases := []Release{createRelease("1.1.0", false), createRelease("1.1.1", true)}
+
+	asset, err := ResolveVersionJar(releases, "1.1.x", true)
+	as.ok(err)
+
+	as.eq(jarname("1.1.0"), asset.Name)
+}
+
+func TestResolveVersionJarCanFindVersionWithinRange(t *testing.T) {
+	as := asserts(t)
+	version := "0.8.2"
+	releases := []Release{createRelease(version, false)}
+
+	asset, err := ResolveVersionJar(releases, ">=0.5.0 <0.8.0 || >=0.8.1 !0.8.3", false)
+	as.ok(err)
+
+	as.eq(Asset{Name: jarname(version), Url: jarurl(version)}, *asset)
+}
+
+func TestResolveVersionJarReturnsErrorIfNoMatchingJar(t *testing.T) {
+	as := asserts(t)
+	versionFilter := ">=0.5.0 <0.8.0"
+	releases := []Release{createRelease("0.8.2", false)}
+
+	_, err := ResolveVersionJar(releases, versionFilter, false)
+	as.err("Cannot find a release that matches version spec `"+versionFilter+"` and stable-only=false", err)
+}
+
+func TestResolveVersionJarReturnsErrorIfCannotParseFilterVersion(t *testing.T) {
+	as := asserts(t)
+	_, err := ResolveVersionJar([]Release{createRelease("1.1.1", true)}, "mumbojumborelease", true)
+	as.err("Don't know how to parse version spec `mumbojumborelease`: Could not get version from string: \"mumbojumborelease\"", err)
+}
+
+func TestResolveVersionJarReturnsErrorIfCannotParseReleaseVersion(t *testing.T) {
+	as := asserts(t)
+	_, err := ResolveVersionJar([]Release{createRelease("mumbojumborelease", true)}, "1.1.1", true)
+	as.err("Cannot parse release version `mumbojumborelease`; does not conform to semantic version (No Major.Minor.Patch elements found)", err)
+}
+
+func TestResolveVersionJarReturnErrorIfCannotFindAssetJarForRelease(t *testing.T) {
+	as := asserts(t)
+	release := createRelease("1.1.1", false)
+	release.Assets[0].Name = "not a jar"
+
+	_, err := ResolveVersionJar([]Release{release}, "1.1.1", true)
+	as.err("Could not resolve jar asset for version 1.1.1", err)
+}
+
+func TestResolveVersionJarReturnErrorIfThereAreNoReleases(t *testing.T) {
+	as := asserts(t)
+	_, err := ResolveVersionJar([]Release{}, "", true)
+	as.err("Could not find any releases to filter", err)
+}
diff --git a/github/test_helpers_test.go b/github/test_helpers_test.go
new file mode 100644
index 0000000..7239ecc
--- /dev/null
+++ b/github/test_helpers_test.go
@@ -0,0 +1,60 @@
+package github
+
+import (
+	"testing"
+)
+
+type asserter struct {
+	t *testing.T
+}
+
+func (a *asserter) eq(expected, actual interface{}) {
+	a.t.Helper()
+	if expected != actual {
+		a.t.Errorf("Expected %v to equal %v", actual, expected)
+	}
+}
+
+func (a *asserter) neq(expected, actual interface{}) {
+	a.t.Helper()
+	if expected == actual {
+		a.t.Errorf("Expected %v to not equal %v", actual, expected)
+	}
+}
+
+func (a *asserter) err(expected string, e error) {
+	a.t.Helper()
+	if nil == e {
+		a.t.Errorf("Expected error %q, but got nil", expected)
+		return
+	}
+
+	if e.Error() != expected {
+		a.t.Errorf("Expected error %q, but got %q", expected, e)
+	}
+}
+
+func (a *asserter) ok(err error) {
+	a.t.Helper()
+	if nil != err {
+		a.t.Errorf("Expected no error, but got %v", err)
+	}
+}
+
+func (a *asserter) is(b bool) {
+	a.t.Helper()
+	if !b {
+		a.t.Errorf("Expected to be true")
+	}
+}
+
+func (a *asserter) not(b bool) {
+	a.t.Helper()
+	if b {
+		a.t.Errorf("Expected to be false")
+	}
+}
+
+func asserts(t *testing.T) *asserter {
+	return &asserter{t: t}
+}