Merge pull request #91 from paketo-buildpacks/resolve-env

Adds sherpa.ResolveBool for use in helpers

sherpa/env_var.go

@@ -19,6 +19,7 @@ package sherpa
 import (
 	"fmt"
 	"os"
+	"strconv"
 	"strings"
 )
 
@@ -50,3 +51,19 @@ func GetEnvWithDefault(name string, def string) string {
 	}
 	return def
 }
+
+// ResolveBool resolves a boolean value for a configuration option. Returns true for 1, t, T, TRUE, true, True. Returns
+// false for all other values or unset.
+func ResolveBool(name string) bool {
+	s, ok := os.LookupEnv(name)
+	if !ok {
+		return false
+	}
+
+	t, err := strconv.ParseBool(s)
+	if err != nil {
+		return false
+	}
+
+	return t
+}

sherpa/env_var_test.go

@@ -103,4 +103,53 @@ func testEnvVar(t *testing.T, context spec.G, it spec.S) {
 			Expect(sherpa.GetEnvWithDefault("ANOTHER_KEY", "default-value")).To(Equal("default-value"))
 		})
 	})
+
+	context("ResolveBool", func() {
+		context("variable not set", func() {
+			it("returns false if not set", func() {
+				Expect(sherpa.ResolveBool("TEST_KEY")).To(BeFalse())
+			})
+		})
+
+		context("variable is set to true value", func() {
+			it.After(func() {
+				Expect(os.Unsetenv("TEST_KEY")).To(Succeed())
+			})
+
+			it("returns true", func() {
+				for _, form := range []string{"1", "t", "T", "TRUE", "true", "True"} {
+					Expect(os.Setenv("TEST_KEY", form))
+					Expect(sherpa.ResolveBool("TEST_KEY")).To(BeTrue())
+					Expect(os.Unsetenv("TEST_KEY")).To(Succeed())
+				}
+			})
+		})
+
+		context("variable is set to non-true value", func() {
+			it.After(func() {
+				Expect(os.Unsetenv("TEST_KEY")).To(Succeed())
+			})
+
+			it("returns false", func() {
+				for _, form := range []string{"0", "f", "F", "FALSE", "false", "False"} {
+					Expect(os.Setenv("TEST_KEY", form))
+					Expect(sherpa.ResolveBool("TEST_KEY")).To(BeFalse())
+					Expect(os.Unsetenv("TEST_KEY")).To(Succeed())
+				}
+			})
+		})
+
+		context("variable is set to an invalid value", func() {
+			it.After(func() {
+				Expect(os.Unsetenv("TEST_KEY")).To(Succeed())
+			})
+
+			it("returns false", func() {
+				Expect(os.Setenv("TEST_KEY", "foo"))
+				Expect(sherpa.ResolveBool("TEST_KEY")).To(BeFalse())
+				Expect(os.Unsetenv("TEST_KEY")).To(Succeed())
+			})
+		})
+
+	})
 }