Nit fixes to init algo and add test

- Removes getVersionConstituents(), inline its simplified implementation.
- Adds test for getProjectPropertiesFromVersion() function.

Author: darkowlzz

cmd/dep/init.go

@@ -231,40 +231,29 @@ func hasImportPathPrefix(s, prefix string) bool {
 	return strings.HasPrefix(s, prefix+"/")
 }
 
-// getVersionConstituents extracts version constituents
-func getVersionConstituents(v gps.Version) (version, revision string) {
-	switch tv := v.(type) {
-	case gps.UnpairedVersion:
-		version = tv.String()
-	case gps.Revision:
-		revision = tv.String()
-	case gps.PairedVersion:
-		version = tv.Unpair().String()
-		revision = tv.Underlying().String()
-	}
-
-	return version, revision
-}
-
 // getProjectPropertiesFromVersion takes a gps.Version and returns a proper
 // gps.ProjectProperties with Constraint value based on the provided version.
 func getProjectPropertiesFromVersion(v gps.Version) gps.ProjectProperties {
 	pp := gps.ProjectProperties{}
 
-	// constituent version and revision. Ignoring revison for manifest.
-	cv, _ := getVersionConstituents(v)
+	// extract version and ignore if it's revision only
+	switch tv := v.(type) {
+	case gps.PairedVersion:
+		v = tv.Unpair()
+	case gps.Revision:
+		return pp
+	}
 
 	switch v.Type() {
-	case gps.IsBranch:
-		pp.Constraint = gps.NewBranch(cv)
-	case gps.IsVersion:
-		pp.Constraint = gps.NewVersion(cv)
+	case gps.IsBranch, gps.IsVersion:
+		pp.Constraint = v
 	case gps.IsSemver:
 		// TODO: remove "^" when https://github.com/golang/dep/issues/225 is ready.
-		c, _ := gps.NewSemverConstraint("^" + cv)
+		c, err := gps.NewSemverConstraint("^" + v.String())
+		if err != nil {
+			panic(err)
+		}
 		pp.Constraint = c
-	case gps.IsRevision:
-		pp.Constraint = nil
 	}
 
 	return pp

cmd/dep/init_test.go

@@ -4,7 +4,11 @@
 
 package main
 
-import "testing"
+import (
+	"testing"
+
+	"github.com/sdboyer/gps"
+)
 
 func TestContains(t *testing.T) {
 	a := []string{"a", "b", "abcd"}
@@ -33,3 +37,44 @@ func TestIsStdLib(t *testing.T) {
 		}
 	}
 }
+
+func TestGetProjectPropertiesFromVersion(t *testing.T) {
+	cases := []struct {
+		version  gps.Version
+		expected gps.Version
+	}{
+		{
+			version:  gps.NewBranch("foo-branch").Is("some-revision"),
+			expected: gps.NewBranch("foo-branch"),
+		},
+		{
+			version:  gps.NewVersion("foo-version").Is("some-revision"),
+			expected: gps.NewVersion("foo-version"),
+		},
+		{
+			version:  gps.Revision("alsjd934"),
+			expected: nil,
+		},
+		// This fails. Hence, testing separately below.
+		// {
+		// 	version: gps.NewVersion("v1.0.0"),
+		// 	expected: gps.NewVersion("^1.0.0"),
+		// },
+	}
+
+	for _, c := range cases {
+		actualProp := getProjectPropertiesFromVersion(c.version)
+		if c.expected != actualProp.Constraint {
+			t.Fatalf("Expected %q to be equal to %q", actualProp.Constraint, c.expected)
+		}
+	}
+
+	outsemver := getProjectPropertiesFromVersion(gps.NewVersion("v1.0.0"))
+	expectedSemver, _ := gps.NewSemverConstraint("^1.0.0")
+	// Comparing outsemver.Constraint and expectedSemver fails with error
+	// "comparing uncomparable type semver.rangeConstraint", although they have
+	// same value and same type "gps.semverConstraint" as per "reflect".
+	if outsemver.Constraint.String() != expectedSemver.String() {
+		t.Fatalf("Expected %q to be equal to %q", outsemver, expectedSemver)
+	}
+}