Issue #1965 - Fix label resolution for non-captured regex (#1969)

<!-- Thanks for sending a PR! Before submitting:

1. If this is your first PR, please read CONTRIBUTING.md and sign the
CLA
   first. We cannot review code without a signed CLA.
2. Please file an issue *first*. All features and most bug fixes should
have
an associated issue with a design discussed and decided upon. Small bug
   fixes and documentation improvements don't need issues.
3. New features and bug fixes must have tests. Documentation may need to
be updated. If you're unsure what to update, send the PR, and we'll
discuss
   in review.
-->

**What type of PR is this?**
Bug fix


**What package or component does this PR mostly affect?**
resolve

**What does this PR do? Why is it needed?**
This change resolves an issue with regex_replace where the default
behavior attempts to perform a string replacement using regex, but
results in an invalid label.

**Which issues(s) does this PR fix?**
Fixes #1965

**Other notes for review**

resolve/config.go

@@ -64,7 +64,12 @@ func (o regexpOverrideSpec) matches(imp ImportSpec, lang string) bool {
 }
 
 func (o regexpOverrideSpec) resolveRegexpDep(imp ImportSpec) label.Label {
-
+	// If "$" is found in the dependency string, then backreferences exist and
+	// ReplaceAllString() should be run on the string to substitute in the
+	// correct replacement strings to build the label.
+	if !strings.Contains(o.dep.String(), "$") {
+	    return o.dep
+	}
 	resolvedDepWithRegex := o.ImpRegex.ReplaceAllString(imp.Imp, o.dep.String())
 	resolvedLabel, err := label.Parse(resolvedDepWithRegex)
 	if err != nil {

resolve/resolve_test.go

@@ -30,6 +30,10 @@ func TestFindRuleWithOverride_ParentTraversal(t *testing.T) {
 		{Key: "resolve_regexp", Value: "go ^github.com/foo/(.*)/(.*)$ @com_example//$1/bar_sub_dir/$2:replacement"},
 	}, rootCfg)
 
+	nonCapturedRegexpCfg := getConfig(t, "", []rule.Directive{
+		{Key: "resolve_regexp", Value: "py github.com/\\.* @com_example//regexp:no_replacement"},
+	}, nil)
+
 	tests := []struct {
 		name      string
 		cfg       *config.Config
@@ -103,13 +107,21 @@ func TestFindRuleWithOverride_ParentTraversal(t *testing.T) {
 			wantFound:  true,
 		},
 		{
-			name:       "Target resolves to label populated by multipe captured regexp",
+			name:       "Target resolves to label populated by multiple captured regexp",
 			cfg:        multipleExpDualResolveRegexpCfg,
 			importSpec: ImportSpec{Lang: "go", Imp: "github.com/foo/foo_package/baz"},
 			lang:       "go",
 			want:       getTestLabel(t, "@com_example//foo_package/bar_sub_dir/baz:replacement"),
 			wantFound:  true,
-		}, 
+		},
+		{
+			name:       "Target resolves to label populated by the configuration with no captured regex",
+			cfg:        nonCapturedRegexpCfg,
+			importSpec: ImportSpec{Lang: "py", Imp: "github.com/root/repo"},
+			lang:       "py",
+			want:       getTestLabel(t, "@com_example//regexp:no_replacement"),
+			wantFound:  true,
+		},
 	}
 
 	for _, tt := range tests {