expose defaultMinimumVersion and getMinimumVersion (#3352)

Signed-off-by: Paul S. Schweigert <paul@paulschweigert.com>

Author: psschwei

version/version.go

@@ -33,20 +33,21 @@ const (
 	// NOTE: If you are changing this line, please also update the minimum kubernetes
 	// version listed here:
 	// https://github.com/knative/docs/blob/main/docs/snippets/prerequisites.md
-	defaultMinimumVersion = "v1.34.0"
-)
 
-// MinimumVersion returns the minimum Kubernetes version Knative is built
-// and tested against. The returned value has a leading "v" (e.g. "v1.34.0").
-func MinimumVersion() string {
-	return defaultMinimumVersion
-}
+	// DefaultKubernetesMinVersion is the default minimum Kubernetes version
+	// Knative is built and tested against. The value has a leading "v"
+	// (e.g. "v1.34.0").
+	DefaultKubernetesMinVersion = "v1.34.0"
+)
 
-func getMinimumVersion() string {
+// KubernetesMinimumVersion returns the minimum Kubernetes version required by
+// Knative. It returns the value of the KUBERNETES_MIN_VERSION environment
+// variable if set, otherwise DefaultKubernetesMinVersion.
+func KubernetesMinimumVersion() string {
 	if v := os.Getenv(KubernetesMinVersionKey); v != "" {
 		return v
 	}
-	return defaultMinimumVersion
+	return DefaultKubernetesMinVersion
 }
 
 // CheckMinimumVersion checks if the currently installed version of
@@ -65,7 +66,7 @@ func CheckMinimumVersion(versioner discovery.ServerVersionInterface) error {
 	if err != nil {
 		return err
 	}
-	minimumVersion, err := semver.Make(normalizeVersion(getMinimumVersion()))
+	minimumVersion, err := semver.Make(normalizeVersion(KubernetesMinimumVersion()))
 	if err != nil {
 		return err
 	}

version/version_test.go

@@ -99,18 +99,27 @@ func TestVersionCheck(t *testing.T) {
 
 			err := CheckMinimumVersion(test.actualVersion)
 			if err == nil && test.wantError {
-				t.Errorf("Expected an error for minimum: %q, actual: %v", getMinimumVersion(), test.actualVersion)
+				t.Errorf("Expected an error for minimum: %q, actual: %v", KubernetesMinimumVersion(), test.actualVersion)
 			}
 
 			if err != nil && !test.wantError {
-				t.Errorf("Expected no error but got %v for minimum: %q, actual: %v", err, getMinimumVersion(), test.actualVersion)
+				t.Errorf("Expected no error but got %v for minimum: %q, actual: %v", err, KubernetesMinimumVersion(), test.actualVersion)
 			}
 		})
 	}
 }
 
-func TestMinimumVersion(t *testing.T) {
-	if got := MinimumVersion(); got != defaultMinimumVersion {
-		t.Errorf("MinimumVersion() = %q, want %q", got, defaultMinimumVersion)
-	}
+func TestKubernetesMinimumVersion(t *testing.T) {
+	t.Run("default", func(t *testing.T) {
+		t.Setenv(KubernetesMinVersionKey, "")
+		if got := KubernetesMinimumVersion(); got != DefaultKubernetesMinVersion {
+			t.Errorf("KubernetesMinimumVersion() = %q, want %q", got, DefaultKubernetesMinVersion)
+		}
+	})
+	t.Run("override", func(t *testing.T) {
+		t.Setenv(KubernetesMinVersionKey, "v1.99.0")
+		if got := KubernetesMinimumVersion(); got != "v1.99.0" {
+			t.Errorf("KubernetesMinimumVersion() = %q, want %q", got, "v1.99.0")
+		}
+	})
 }