fix: Fix error message when Tag can not be acquired

chglog_test.go

@@ -95,9 +95,63 @@ func TestGeneratorNotFoundCommits(t *testing.T) {
 		},
 	})
 
+	buf := &bytes.Buffer{}
+	err := gen.Generate(buf, "foo")
+	assert.Error(err)
+	assert.Equal("", buf.String())
+}
+
+func TestGeneratorNotFoundCommitsOne(t *testing.T) {
+	assert := assert.New(t)
+	testName := "not_found"
+
+	setup(testName, func(git gitcmd.Client) {
+		git.Exec("commit", "--allow-empty", "--date", "Mon Jan 1 00:00:00 2018 +0000", "-m", "chore(*): First commit")
+	})
+
+	gen := NewGenerator(&Config{
+		Bin:        "git",
+		WorkingDir: filepath.Join(testRepoRoot, testName),
+		Template:   filepath.Join(cwd, "testdata", testName+".md"),
+		Info: &Info{
+			RepositoryURL: "/~https://github.com/git-chglog/git-chglog",
+		},
+		Options: &Options{
+			CommitFilters:        map[string][]string{},
+			CommitSortBy:         "Scope",
+			CommitGroupBy:        "Type",
+			CommitGroupSortBy:    "Title",
+			CommitGroupTitleMaps: map[string]string{},
+			HeaderPattern:        "^(\\w*)(?:\\(([\\w\\$\\.\\-\\*\\s]*)\\))?\\:\\s(.*)$",
+			HeaderPatternMaps: []string{
+				"Type",
+				"Scope",
+				"Subject",
+			},
+			IssuePrefix: []string{
+				"#",
+				"gh-",
+			},
+			RefActions:   []string{},
+			MergePattern: "^Merge pull request #(\\d+) from (.*)$",
+			MergePatternMaps: []string{
+				"Ref",
+				"Source",
+			},
+			RevertPattern: "^Revert \"([\\s\\S]*)\"$",
+			RevertPatternMaps: []string{
+				"Header",
+			},
+			NoteKeywords: []string{
+				"BREAKING CHANGE",
+			},
+		},
+	})
+
 	buf := &bytes.Buffer{}
 	err := gen.Generate(buf, "foo")
 	assert.Contains(err.Error(), "\"foo\" was not found")
+	assert.Error(err)
 	assert.Equal("", buf.String())
 }
 

tag_reader.go

@@ -1,6 +1,7 @@
 package chglog
 
 import (
+	"fmt"
 	"regexp"
 	"strconv"
 	"strings"
@@ -33,7 +34,7 @@ func (r *tagReader) ReadAll() ([]*Tag, error) {
 	tags := []*Tag{}
 
 	if err != nil {
-		return tags, err
+		return tags, fmt.Errorf("failed to get git-tag: %s", err.Error())
 	}
 
 	lines := strings.Split(out, "\n")