kubectl: refactor addFromEnvFile, write tests

pkg/kubectl/BUILD

@@ -14,6 +14,7 @@ go_test(
         "cluster_test.go",
         "configmap_test.go",
         "deployment_test.go",
+        "env_file_test.go",
         "generate_test.go",
         "kubectl_test.go",
         "namespace_test.go",

pkg/kubectl/env_file.go

@@ -28,6 +28,47 @@ import (
 	"k8s.io/apimachinery/pkg/util/validation"
 )
 
+var utf8bom = []byte{0xEF, 0xBB, 0xBF}
+
+// proccessEnvFileLine returns a blank key if the line is empty or a comment.
+// The value will be retrieved from the environment if necessary.
+func proccessEnvFileLine(line []byte, filePath string,
+	currentLine int) (key, value string, err error) {
+
+	if !utf8.Valid(line) {
+		return ``, ``, fmt.Errorf("env file %s contains invalid utf8 bytes at line %d: %v",
+			filePath, currentLine+1, line)
+	}
+
+	// We trim UTF8 BOM from the first line of the file but no others
+	if currentLine == 0 {
+		line = bytes.TrimPrefix(line, utf8bom)
+	}
+
+	// trim the line from all leading whitespace first
+	line = bytes.TrimLeftFunc(line, unicode.IsSpace)
+
+	// If the line is empty or a comment, we return a blank key/value pair.
+	if len(line) == 0 || line[0] == '#' {
+		return ``, ``, nil
+	}
+
+	data := strings.SplitN(string(line), "=", 2)
+	key = data[0]
+	if errs := validation.IsCIdentifier(key); len(errs) != 0 {
+		return ``, ``, fmt.Errorf("%q is not a valid key name: %s", key, strings.Join(errs, ";"))
+	}
+
+	if len(data) == 2 {
+		value = data[1]
+	} else {
+		// No value (no `=` in the line) is a signal to obtain the value
+		// from the environment.
+		value = os.Getenv(key)
+	}
+	return
+}
+
 // addFromEnvFile processes an env file allows a generic addTo to handle the
 // collection of key value pairs or returns an error.
 func addFromEnvFile(filePath string, addTo func(key, value string) error) error {
@@ -39,38 +80,23 @@ func addFromEnvFile(filePath string, addTo func(key, value string) error) error
 
 	scanner := bufio.NewScanner(f)
 	currentLine := 0
-	utf8bom := []byte{0xEF, 0xBB, 0xBF}
 	for scanner.Scan() {
+		// Proccess the current line, retrieving a key/value pair if
+		// possible.
 		scannedBytes := scanner.Bytes()
-		if !utf8.Valid(scannedBytes) {
-			return fmt.Errorf("env file %s contains invalid utf8 bytes at line %d: %v", filePath, currentLine+1, scannedBytes)
+		key, value, err := proccessEnvFileLine(scannedBytes, filePath, currentLine)
+		if err != nil {
+			return err
 		}
-		// We trim UTF8 BOM
-		if currentLine == 0 {
-			scannedBytes = bytes.TrimPrefix(scannedBytes, utf8bom)
-		}
-		// trim the line from all leading whitespace first
-		line := strings.TrimLeftFunc(string(scannedBytes), unicode.IsSpace)
 		currentLine++
-		// line is not empty, and not starting with '#'
-		if len(line) > 0 && !strings.HasPrefix(line, "#") {
-			data := strings.SplitN(line, "=", 2)
-			key := data[0]
-			if errs := validation.IsCIdentifier(key); len(errs) != 0 {
-				return fmt.Errorf("%q is not a valid key name: %s", key, strings.Join(errs, ";"))
-			}
 
-			value := ""
-			if len(data) > 1 {
-				// pass the value through, no trimming
-				value = data[1]
-			} else {
-				// a pass-through variable is given
-				value = os.Getenv(key)
-			}
-			if err = addTo(key, value); err != nil {
-				return err
-			}
+		if len(key) == 0 {
+			// no key means line was empty or a comment
+			continue
+		}
+
+		if err = addTo(key, value); err != nil {
+			return err
 		}
 	}
 	return nil

pkg/kubectl/env_file_test.go

@@ -0,0 +1,103 @@
+/*
+Copyright 2017 The Kubernetes Authors.
+
+Licensed under the Apache License, Version 2.0 (the "License");
+you may not use this file except in compliance with the License.
+You may obtain a copy of the License at
+
+    http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License.
+*/
+
+package kubectl
+
+import (
+	"os"
+	"strings"
+	"testing"
+)
+
+// Test the cases of proccessEnvFileLine that can be run without touching the
+// environment.
+func Test_processEnvFileLine(t *testing.T) {
+	testCases := []struct {
+		name          string
+		line          []byte
+		currentLine   int
+		expectedKey   string
+		expectedValue string
+		expectedErr   string
+	}{
+		{"the utf8bom is trimmed on the first line",
+			append(utf8bom, 'a', '=', 'c'), 0, "a", "c", ""},
+
+		{"the utf8bom is NOT trimmed on the second line",
+			append(utf8bom, 'a', '=', 'c'), 1, "", "", "not a valid key name"},
+
+		{"no key is returned on a comment line",
+			[]byte{' ', '#', 'c'}, 0, "", "", ""},
+
+		{"no key is returned on a blank line",
+			[]byte{' ', ' ', '\t'}, 0, "", "", ""},
+
+		{"key is returned even with no value",
+			[]byte{' ', 'x', '='}, 0, "x", "", ""},
+	}
+	for _, c := range testCases {
+		key, value, err := proccessEnvFileLine(c.line, `filename`, c.currentLine)
+		t.Logf("Testing that %s.", c.name)
+		if c.expectedKey != key {
+			t.Errorf("\texpected key %q, received %q", c.expectedKey, key)
+		}
+		if c.expectedValue != value {
+			t.Errorf("\texpected value %q, received %q", c.expectedValue, value)
+		}
+		if len(c.expectedErr) == 0 {
+			if err != nil {
+				t.Errorf("\tunexpected err %v", err)
+			}
+		} else {
+			if !strings.Contains(err.Error(), c.expectedErr) {
+				t.Errorf("\terr %v doesn't match expected %q", err, c.expectedErr)
+			}
+		}
+	}
+}
+
+// proccessEnvFileLine needs to fetch the value from the environment if no
+// equals sign is provided.
+// For example:
+//
+//	my_key1=alpha
+//	my_key2=beta
+//	my_key3
+//
+// In this file, my_key3 must be fetched from the environment.
+// Test this capability.
+func Test_processEnvFileLine_readEnvironment(t *testing.T) {
+	const realKey = "k8s_test_env_file_key"
+	const realValue = `my_value`
+
+	// Just in case, these two lines ensure the environment is restored to
+	// its original state.
+	original := os.Getenv(realKey)
+	defer func() { os.Setenv(realKey, original) }()
+
+	os.Setenv(realKey, `my_value`)
+
+	key, value, err := proccessEnvFileLine([]byte(realKey), `filename`, 3)
+	if err != nil {
+		t.Fatal(err)
+	}
+	if key != realKey {
+		t.Errorf(`expected key %q, received %q`, realKey, key)
+	}
+	if value != realValue {
+		t.Errorf(`expected value %q, received %q`, realValue, value)
+	}
+}