Ensure matching modules with metadata when requested

config/module/versions.go

@@ -3,14 +3,18 @@ package module
 import (
 	"errors"
 	"fmt"
+	"regexp"
 	"sort"
+	"strings"
 
 	version "github.com/hashicorp/go-version"
 	"github.com/hashicorp/terraform/registry/response"
 )
 
 const anyVersion = ">=0.0.0"
 
+var explicitEqualityConstraint = regexp.MustCompile("^=[0-9]")
+
 // return the newest version that satisfies the provided constraint
 func newest(versions []string, constraint string) (string, error) {
 	if constraint == "" {
@@ -50,6 +54,11 @@ func newest(versions []string, constraint string) (string, error) {
 		return iv.GreaterThan(jv)
 	})
 
+	// Store whether the constraint contains a metadata requirement,
+	// so we can check if we should be returning a specific metadata version
+	constraintMeta := strings.SplitAfterN(cs.String(), "+", 2)
+	equalsConstraint := explicitEqualityConstraint.MatchString(cs.String())
+
 	// versions are now in order, so just find the first which satisfies the
 	// constraint
 	for i := range versions {
@@ -58,6 +67,12 @@ func newest(versions []string, constraint string) (string, error) {
 			continue
 		}
 		if cs.Check(v) {
+			// Constraint has metadata and is explicit equality
+			if len(constraintMeta) > 1 && equalsConstraint {
+				if constraintMeta[1] != v.Metadata() {
+					continue
+				}
+			}
 			return versions[i], nil
 		}
 	}

config/module/versions_test.go

@@ -58,3 +58,29 @@ func TestNewestInvalidModuleVersion(t *testing.T) {
 		t.Fatalf("expected version %q, got %q", expected, m.Version)
 	}
 }
+
+func TestNewestModulesWithMetadata(t *testing.T) {
+	mpv := &response.ModuleProviderVersions{
+		Source: "registry/test/module",
+		Versions: []*response.ModuleVersion{
+			{Version: "0.9.0"},
+			{Version: "0.9.0+def"},
+			{Version: "0.9.0+abc"},
+			{Version: "0.9.0+xyz"},
+		},
+	}
+
+	// with metadata and explicit version request
+	expected := "0.9.0+def"
+	m, _ := newestVersion(mpv.Versions, "=0.9.0+def")
+	if m.Version != expected {
+		t.Fatalf("expected version %q, got %q", expected, m.Version)
+	}
+
+	// respect explicit equality, but >/</~ will be ignored
+	expected = "0.9.0"
+	m, _ = newestVersion(mpv.Versions, "~>0.9.0+abc")
+	if m.Version != expected {
+		t.Fatalf("expected version %q, got %q", expected, m.Version)
+	}
+}