diff --git a/.gitignore b/.gitignore
index 91abe37..556eb12 100644
--- a/.gitignore
+++ b/.gitignore
@@ -5,6 +5,7 @@ artifacts
 *.dll
 *.so
 *.dylib
+coverage
 
 # Test binary, built with `go test -c`
 *.test
diff --git a/Makefile b/Makefile
index 98771f9..a71580b 100644
--- a/Makefile
+++ b/Makefile
@@ -1,6 +1,7 @@
 # Inspired from https://dustinspecker.com/posts/go-combined-unit-integration-code-coverage/ and https://netdevops.me/2023/test-coverage-for-go-integration-tests/
 BIN_DIR = $(CURDIR)/artifacts
 BINARY = $(BIN_DIR)/gocustomurls
+COVERAGE_DIR = $(CURDIR)/coverage
 CURRENT_DIR = $(shell pwd)
 CUR_TAG = $(shell git tag | sort -g | tail -1 | cut -c 2-)
 VERSION_NUMBER ?= 0.0.0
@@ -29,4 +30,25 @@ lint:
 
 .PHONY: build
 build:
-	go build -o $(BINARY)
\ No newline at end of file
+	go build -o $(BINARY)
+
+.PHONY: build-debug
+build-debug:
+	mkdir -p $(BIN_DIR)
+	go build -cover -o $(BINARY) .
+
+.PHONY: test
+test: build-debug
+	rm -rf $(COVERAGE_DIR)
+	mkdir -p $(COVERAGE_DIR)
+	go test -cover ./... -args -test.gocoverdir="$(COVERAGE_DIR)"
+
+.PHONY: coverage-full
+coverage-full: test
+	go tool covdata textfmt -i=$(COVERAGE_DIR) -o $(COVERAGE_DIR)/coverage.out
+	go tool cover -func=$(COVERAGE_DIR)/coverage.out
+
+.PHONY: coverage-html
+coverage-html: coverage-full
+	go tool cover -html=./coverage/coverage.out -o ./coverage/coverage.html
+	open ./coverage/coverage.html
\ No newline at end of file
diff --git a/conf.go b/conf.go
index 65c0eea..9919890 100644
--- a/conf.go
+++ b/conf.go
@@ -85,13 +85,20 @@ func getDefaults() (map[string]string, error) {
 	}
 	m["rulesFp"] = filepath.Join(confDir, "gocustomcurls", "rules.json")
 	m["confFp"] = filepath.Join(confDir, "gocustomcurls", "config.json")
-	m["logfp"] = filepath.Join(homeDir, ".gocustomurls", "logs", "app.log")
+	m["logFp"] = filepath.Join(homeDir, ".gocustomurls", "logs", "app.log")
 	return m, nil
 }
 
-func generateDefaultConfigFile() (parsedConf, error) {
+func generateDefaultConfigFile(defaultObj map[string]string) (parsedConf, error) {
 	var p parsedConf
-	defaults, err := getDefaults()
+	var err error
+	var defaults map[string]string
+	if len(defaultObj) == 0 {
+		defaults, err = getDefaults()
+	} else {
+		defaults = defaultObj
+	}
+
 	if err != nil {
 		return p, err
 	}
@@ -127,7 +134,7 @@ func checkIfSizeIsConfigured(fsize string) (bool, error) {
 		}
 	}
 	if len(found) == 0 {
-		return false, fmt.Errorf("%s has the incorrect suffix, Please use one of this suffixes {\"K\", \"KB\",\"M\", \"MB\", \"G\", \"GB\"}", fsize)
+		return false, fmt.Errorf("%s has the incorrect suffix, Please use one of this suffixes {\"KB\", \"MB\", \"GB\"}", fsize)
 	}
 
 	return true, nil
@@ -141,7 +148,7 @@ func (c *Config) LoadMainConfigFile(fp string) (parsedConf, error) {
 	if !ok {
 		// generate config file
 		errorLog.Println("Warning, generating default config file")
-		conf, err = generateDefaultConfigFile()
+		conf, err = generateDefaultConfigFile(map[string]string{})
 		if err != nil {
 			return conf, err
 		}
diff --git a/conf_test.go b/conf_test.go
new file mode 100644
index 0000000..b2d83d7
--- /dev/null
+++ b/conf_test.go
@@ -0,0 +1,126 @@
+package main
+
+import (
+	"fmt"
+	"testing"
+
+	"github.com/stretchr/testify/assert"
+)
+
+func TestLoadMappingFile(t *testing.T) {
+
+	t.Run("load the mapping file correctly - initial load", func(t *testing.T) {
+		tmpDir := t.TempDir()
+
+		mkDirForTest(t, fmt.Sprintf("%s/tmp", tmpDir))
+		rulesJsonFp := "testData/rules.json"
+
+		expected := fmt.Sprintf("%s/tmp/rules.json", tmpDir)
+
+		cpFileForTest(t, rulesJsonFp, expected)
+
+		cfg := &Config{}
+
+		assert.Equal(t, cfg.MappingFilePath, "")
+		assert.Empty(t, cfg.MappingRules)
+		err := cfg.LoadMappingFile(expected)
+		assert.Equal(t, err, nil)
+		assert.Equal(t, cfg.MappingFilePath, expected)
+		assert.NotEmpty(t, cfg.MappingRules)
+	})
+
+	t.Run("load the mapping file correctly - reload", func(t *testing.T) {
+		tmpDir := t.TempDir()
+
+		mkDirForTest(t, fmt.Sprintf("%s/tmp", tmpDir))
+		rulesJsonFp := "testData/rules.json"
+
+		expected := fmt.Sprintf("%s/tmp/rules.json", tmpDir)
+
+		cpFileForTest(t, rulesJsonFp, expected)
+
+		cfg := &Config{}
+
+		assert.Equal(t, cfg.MappingFilePath, "")
+		assert.Empty(t, cfg.MappingRules)
+		err := cfg.LoadMappingFile(expected)
+		assert.Equal(t, err, nil)
+		assert.Equal(t, cfg.MappingFilePath, expected)
+		assert.NotEmpty(t, cfg.MappingRules)
+		oldRules := cfg.MappingRules
+
+		rulesJsonFp = "testData/rules2.json"
+
+		cpFileForTest(t, rulesJsonFp, expected)
+
+		err = cfg.LoadMappingFile(expected)
+		assert.Equal(t, err, nil)
+		assert.Equal(t, cfg.MappingFilePath, expected)
+		assert.NotEmpty(t, cfg.MappingRules)
+
+		newRules := cfg.MappingRules
+
+		assert.NotEqualValues(t, oldRules, newRules)
+	})
+}
+
+func TestGetDefaults(t *testing.T) {
+	actual, err := getDefaults()
+	assert.Equal(t, err, nil)
+	assert.Contains(t, actual, "rulesFp")
+	assert.Contains(t, actual, "logFp")
+	assert.Contains(t, actual, "confFp")
+}
+
+func TestSizeIsConfigured(t *testing.T) {
+	tests := map[string]struct {
+		input string
+		want  bool
+	}{
+		"wrong input - K":    {input: "5677.45K", want: false},
+		"wrong input - KiB":  {input: "5677.45KiB", want: false},
+		"wrong input - M":    {input: "9.45M", want: false},
+		"wrong input - G":    {input: "9.45G", want: false},
+		"correct input - KB": {input: "5.45KB", want: true},
+		"correct input - MB": {input: "5677.45MB", want: true},
+		"correct input - GB": {input: "9.45GB", want: true},
+	}
+
+	for name, tc := range tests {
+		t.Run(name, func(t *testing.T) {
+			got, _ := checkIfSizeIsConfigured(tc.input)
+			assert.Equal(t, got, tc.want)
+		})
+	}
+}
+
+func TestGenerateConfigFile(t *testing.T) {
+	tmpDir := t.TempDir()
+
+	tempLogsDir := fmt.Sprintf("%s/tmp/logs", tmpDir)
+	tempConfigDir := fmt.Sprintf("%s/tmp/config", tmpDir)
+
+	mkDirForTest(t, tempLogsDir)
+	mkDirForTest(t, tempConfigDir)
+
+	defaultConfig := map[string]string{
+		"rulesFp": fmt.Sprintf("%s/rules.json", tempConfigDir),
+		"confFp":  fmt.Sprintf("%s/config.json", tempConfigDir),
+		"logFp":   fmt.Sprintf("%s/app.log", tempLogsDir),
+	}
+
+	ok := IsDirEmpty(t, tempConfigDir)
+	assert.Equal(t, ok, true)
+	ok = IsDirEmpty(t, tempLogsDir)
+	assert.Equal(t, ok, true)
+
+	expected, err := generateDefaultConfigFile(defaultConfig)
+	assert.Equal(t, err, nil)
+	assert.NotEmpty(t, expected)
+
+	ok = IsDirEmpty(t, tempConfigDir)
+	assert.Equal(t, ok, false)
+	ok = IsDirEmpty(t, tempLogsDir)
+	assert.Equal(t, ok, true)
+
+}
diff --git a/go.mod b/go.mod
index 341eca9..ce261a7 100644
--- a/go.mod
+++ b/go.mod
@@ -1,3 +1,11 @@
 module gocustomurls
 
 go 1.20
+
+require github.com/stretchr/testify v1.9.0
+
+require (
+	github.com/davecgh/go-spew v1.1.1 // indirect
+	github.com/pmezard/go-difflib v1.0.0 // indirect
+	gopkg.in/yaml.v3 v3.0.1 // indirect
+)
diff --git a/go.sum b/go.sum
new file mode 100644
index 0000000..60ce688
--- /dev/null
+++ b/go.sum
@@ -0,0 +1,10 @@
+github.com/davecgh/go-spew v1.1.1 h1:vj9j/u1bqnvCEfJOwUhtlOARqs3+rkHYY13jYWTU97c=
+github.com/davecgh/go-spew v1.1.1/go.mod h1:J7Y8YcW2NihsgmVo/mv3lAwl/skON4iLHjSsI+c5H38=
+github.com/pmezard/go-difflib v1.0.0 h1:4DBwDE0NGyQoBHbLQYPwSUPoCMWR5BEzIk/f1lZbAQM=
+github.com/pmezard/go-difflib v1.0.0/go.mod h1:iKH77koFhYxTK1pcRnkKkqfTogsbg7gZNVY4sRDYZ/4=
+github.com/stretchr/testify v1.9.0 h1:HtqpIVDClZ4nwg75+f6Lvsy/wHu+3BoSGCbBAcpTsTg=
+github.com/stretchr/testify v1.9.0/go.mod h1:r2ic/lqez/lEtzL7wO/rwa5dbSLXVDPFyf8C91i36aY=
+gopkg.in/check.v1 v0.0.0-20161208181325-20d25e280405 h1:yhCVgyC4o1eVCa2tZl7eS0r+SDo693bJlVdllGtEeKM=
+gopkg.in/check.v1 v0.0.0-20161208181325-20d25e280405/go.mod h1:Co6ibVJAznAaIkqp8huTwlJQCZ016jof/cbN4VW5Yz0=
+gopkg.in/yaml.v3 v3.0.1 h1:fxVm/GzAzEWqLHuvctI91KS9hhNmmWOoWu0XTYJS7CA=
+gopkg.in/yaml.v3 v3.0.1/go.mod h1:K4uyk7z7BCEPqu6E+C64Yfv1cQ7kz7rIZviUmN+EgEM=
diff --git a/testData/app.log b/testData/app.log
new file mode 100644
index 0000000..e69de29
diff --git a/testData/config.json b/testData/config.json
new file mode 100644
index 0000000..e69de29
diff --git a/testData/rules.json b/testData/rules.json
new file mode 100644
index 0000000..2403123
--- /dev/null
+++ b/testData/rules.json
@@ -0,0 +1,14 @@
+{
+	"mappings": [
+		{
+			"vanity_url":"scale.dev/x/migrate",
+			"protocol":"git",
+			"real_url":"https://github.com/scale/migrate"
+		},
+		{
+			"vanity_url":"localhost:7070/x/touche",
+			"protocol":"git",
+			"real_url":"https://github.com/mine/touche"
+		}
+	]
+}
diff --git a/testData/rules2.json b/testData/rules2.json
new file mode 100644
index 0000000..aebbb19
--- /dev/null
+++ b/testData/rules2.json
@@ -0,0 +1,19 @@
+{
+	"mappings": [
+		{
+			"vanity_url":"scale.dev/x/migrate",
+			"protocol":"git",
+			"real_url":"https://github.com/scale/migrate"
+		},
+		{
+			"vanity_url":"codeberg.org/woodpecker-plugins/plugin-gitea-release",
+			"protocol":"git",
+			"real_url":"https://codeberg.org/woodpecker-plugins/gitea-release"
+		},
+		{
+			"vanity_url":"localhost:7070/x/touche",
+			"protocol":"git",
+			"real_url":"https://github.com/mine/touche"
+		}
+	]
+}
diff --git a/testUtils_test.go b/testUtils_test.go
new file mode 100644
index 0000000..187658a
--- /dev/null
+++ b/testUtils_test.go
@@ -0,0 +1,65 @@
+package main
+
+import (
+	"io"
+	"os"
+	"testing"
+)
+
+func mkDirForTest(t *testing.T, fp string) {
+	err := os.MkdirAll(fp, os.ModePerm)
+	if err != nil {
+		t.Fatal(err)
+	}
+}
+
+func cpFileForTest(t *testing.T, src string, dst string) {
+	var srcfd *os.File
+	var dstfd *os.File
+	var err error
+	var srcinfo os.FileInfo
+	srcfd, err = os.Open(src)
+	if err != nil {
+		t.Fatal(err)
+	}
+	defer srcfd.Close()
+	dstfd, err = os.Create(dst)
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	defer dstfd.Close()
+	_, err = io.Copy(dstfd, srcfd)
+	if err != nil {
+		t.Fatal(err)
+	}
+	srcinfo, err = os.Stat(src)
+	if err != nil {
+		t.Fatal(err)
+	}
+	err = os.Chmod(dst, srcinfo.Mode())
+	if err != nil {
+		t.Fatal(err)
+	}
+}
+
+func writeForTest(t *testing.T, fp string, data []byte) {
+	err := os.WriteFile(fp, data, 0666)
+	if err != nil {
+		t.Fatal(err)
+	}
+}
+
+func IsDirEmpty(t *testing.T, name string) bool {
+	f, err := os.Open(name)
+	if err != nil {
+		t.Fatal(err)
+	}
+	defer f.Close()
+
+	// read in ONLY one file
+	_, err = f.Readdir(1)
+
+	// and if the file is EOF... well, the dir is empty.
+	return err == io.EOF
+}