Resolve env var values when unmarshalling

Commit 1595c1d accidentally removed the lines that resolve env var
values. This adds env var resolution and adds a test to assert the
behavior.

envlist_test.go

@@ -0,0 +1,52 @@
+package sup
+
+import (
+	"reflect"
+	"testing"
+
+	"gopkg.in/yaml.v2"
+)
+
+func TestEnvListUnmarshalYAML(t *testing.T) {
+	type holder struct {
+		Env EnvList `yaml:"env"`
+	}
+
+	testCases := []struct {
+		input  string
+		expect holder
+	}{
+		{
+
+			input: `
+env:
+  MY_KEY: abc123
+`,
+			expect: holder{
+				Env: EnvList{
+					&EnvVar{Key: "MY_KEY", Value: "abc123"},
+				},
+			},
+		},
+		{
+
+			input: `
+env:
+  MY_KEY: $(echo abc123)
+`,
+			expect: holder{
+				Env: EnvList{
+					&EnvVar{Key: "MY_KEY", Value: "abc123"},
+				},
+			},
+		},
+	}
+
+	for _, tc := range testCases {
+		h := holder{}
+		yaml.Unmarshal([]byte(tc.input), &h)
+		if !reflect.DeepEqual(h, tc.expect) {
+			t.Errorf("Unmarshalling yaml did not produce the expected result. Got:\n%#v\nExpected: %#v\n", h, tc.expect)
+		}
+	}
+}

supfile.go

@@ -192,7 +192,7 @@ func (e *EnvList) UnmarshalYAML(unmarshal func(interface{}) error) error {
 		e.Set(fmt.Sprintf("%v", v.Key), fmt.Sprintf("%v", v.Value))
 	}
 
-	return nil
+	return e.ResolveValues()
 }
 
 // Set key to be equal value in this list.