Refactor providers and add tests

- Add a `baseProvider` struct with common
- Refactor docker, kv(s) and marathon providers (spliting into small pieces)
- Add unit tests

Signed-off-by: Vincent Demeester <vincent@sbr.pm>

provider/provider_test.go

@@ -0,0 +1,170 @@
+package provider
+
+import (
+	"io/ioutil"
+	"os"
+	"strings"
+	"testing"
+	"text/template"
+)
+
+type myProvider struct {
+	baseProvider
+}
+
+func (p *myProvider) Foo() string {
+	return "bar"
+}
+
+func TestConfigurationErrors(t *testing.T) {
+	templateErrorFile, err := ioutil.TempFile("", "provider-configuration-error")
+	if err != nil {
+		t.Fatal(err)
+	}
+	defer os.RemoveAll(templateErrorFile.Name())
+	data := []byte("Not a valid template {{ Bar }}")
+	err = ioutil.WriteFile(templateErrorFile.Name(), data, 0700)
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	templateInvalidTOMLFile, err := ioutil.TempFile("", "provider-configuration-error")
+	if err != nil {
+		t.Fatal(err)
+	}
+	defer os.RemoveAll(templateInvalidTOMLFile.Name())
+	data = []byte(`Hello {{ .Name }}
+{{ Foo }}`)
+	err = ioutil.WriteFile(templateInvalidTOMLFile.Name(), data, 0700)
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	invalids := []struct {
+		provider        *myProvider
+		defaultTemplate string
+		expectedError   string
+		funcMap         template.FuncMap
+		templateObjects interface{}
+	}{
+		{
+			provider: &myProvider{
+				baseProvider{
+					Filename: "/non/existent/template.tmpl",
+				},
+			},
+			expectedError: "open /non/existent/template.tmpl: no such file or directory",
+		},
+		{
+			provider:        &myProvider{},
+			defaultTemplate: "non/existent/template.tmpl",
+			expectedError:   "Asset non/existent/template.tmpl not found",
+		},
+		{
+			provider: &myProvider{
+				baseProvider{
+					Filename: templateErrorFile.Name(),
+				},
+			},
+			expectedError: `function "Bar" not defined`,
+		},
+		{
+			provider: &myProvider{
+				baseProvider{
+					Filename: templateInvalidTOMLFile.Name(),
+				},
+			},
+			expectedError: "Near line 1, key 'Hello': Near line 1: Expected key separator '=', but got '<' instead",
+			funcMap: template.FuncMap{
+				"Foo": func() string {
+					return "bar"
+				},
+			},
+			templateObjects: struct{ Name string }{Name: "bar"},
+		},
+	}
+
+	for _, invalid := range invalids {
+		configuration, err := invalid.provider.getConfiguration(invalid.defaultTemplate, invalid.funcMap, nil)
+		if err == nil || !strings.Contains(err.Error(), invalid.expectedError) {
+			t.Fatalf("should have generate an error with %q, got %v", invalid.expectedError, err)
+		}
+		if configuration != nil {
+			t.Fatalf("shouldn't have return a configuration object : %v", configuration)
+		}
+	}
+}
+
+func TestGetConfiguration(t *testing.T) {
+	templateFile, err := ioutil.TempFile("", "provider-configuration")
+	if err != nil {
+		t.Fatal(err)
+	}
+	defer os.RemoveAll(templateFile.Name())
+	data := []byte(`[backends]
+  [backends.backend1]
+    [backends.backend1.circuitbreaker]
+      expression = "NetworkErrorRatio() > 0.5"
+    [backends.backend1.servers.server1]
+    url = "http://172.17.0.2:80"
+    weight = 10
+    [backends.backend1.servers.server2]
+    url = "http://172.17.0.3:80"
+    weight = 1
+
+[frontends]
+  [frontends.frontend1]
+  backend = "backend1"
+  passHostHeader = true
+    [frontends.frontend11.routes.test_2]
+    rule = "Path"
+    value = "/test"`)
+	err = ioutil.WriteFile(templateFile.Name(), data, 0700)
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	provider := &myProvider{
+		baseProvider{
+			Filename: templateFile.Name(),
+		},
+	}
+	configuration, err := provider.getConfiguration(templateFile.Name(), nil, nil)
+	if err != nil {
+		t.Fatalf("Shouldn't have error out, got %v", err)
+	}
+	if configuration == nil {
+		t.Fatalf("Configuration should not be nil, but was")
+	}
+}
+
+func TestReplace(t *testing.T) {
+	cases := []struct {
+		str      string
+		expected string
+	}{
+		{
+			str:      "",
+			expected: "",
+		},
+		{
+			str:      "foo",
+			expected: "bar",
+		},
+		{
+			str:      "foo foo",
+			expected: "bar bar",
+		},
+		{
+			str:      "somethingfoo",
+			expected: "somethingbar",
+		},
+	}
+
+	for _, c := range cases {
+		actual := replace("foo", "bar", c.str)
+		if actual != c.expected {
+			t.Fatalf("expected %q, got %q, for %q", c.expected, actual, c.str)
+		}
+	}
+}