config: add functions to look up current author

Since we have functions to look up the current committer, also add a set
to look up the current author.  This lets us honor the Git environment
variable settings to handle different values for authors and committers.

config/config.go

@@ -533,6 +533,19 @@ func (c *Configuration) CurrentCommitterTimestamp() time.Time {
 	return c.timestamp
 }
 
+// CurrentAuthor returns the name/email that would be used to author a change
+// with this configuration. In particular, the "user.name" and "user.email"
+// configuration values are used
+func (c *Configuration) CurrentAuthor() (name, email string) {
+	return c.findUserData("author")
+}
+
+// CurrentCommitterTimestamp returns the timestamp that would be used to commit
+// a change with this configuration.
+func (c *Configuration) CurrentAuthorTimestamp() time.Time {
+	return c.timestamp
+}
+
 // RepositoryPermissions returns the permissions that should be used to write
 // files in the repository.
 func (c *Configuration) RepositoryPermissions() os.FileMode {

config/config_test.go

@@ -234,4 +234,24 @@ func TestCurrentUser(t *testing.T) {
 	name, email = cfg.CurrentCommitter()
 	assert.Equal(t, name, "Sam Roe")
 	assert.Equal(t, email, "sroe@example.net")
+
+	cfg = NewFrom(Values{
+		Git: map[string][]string{
+			"user.name":  []string{"Pat Doe"},
+			"user.email": []string{"pdoe@example.org"},
+		},
+		Os: map[string][]string{
+			"GIT_AUTHOR_NAME":  []string{"Sam Roe"},
+			"GIT_AUTHOR_EMAIL": []string{"sroe@example.net"},
+			"EMAIL":            []string{"pdoe@example.com"},
+		},
+	})
+
+	name, email = cfg.CurrentCommitter()
+	assert.Equal(t, name, "Pat Doe")
+	assert.Equal(t, email, "pdoe@example.org")
+
+	name, email = cfg.CurrentAuthor()
+	assert.Equal(t, name, "Sam Roe")
+	assert.Equal(t, email, "sroe@example.net")
 }