test: Add libkpod config tests

- config_test.go for testing libkpod/config.go
- testdata/config.toml as a fixture for config_test.go

Signed-off-by: Steve Milner <smilner@redhat.com>

libkpod/config_test.go

@@ -0,0 +1,54 @@
+package libkpod
+
+import (
+	"io/ioutil"
+	"os"
+	"testing"
+)
+
+// TestConfigToFile ensures Config.ToFile(..) encodes and writes out
+// a Config instance toa a file on disk.
+func TestConfigToFile(t *testing.T) {
+	// Test with a default configuration
+	c := DefaultConfig()
+	tmpfile, err := ioutil.TempFile("", "config")
+	if err != nil {
+		t.Fatalf("Unable to create temporary file: %+v", err)
+	}
+	// Clean up temporary file
+	defer os.Remove(tmpfile.Name())
+
+	// Make the ToFile calls
+	err = c.ToFile(tmpfile.Name())
+	// Make sure no errors occurred while populating the file
+	if err != nil {
+		t.Fatalf("Unable to write to temporary file: %+v", err)
+	}
+
+	// Make sure the file is on disk
+	if _, err := os.Stat(tmpfile.Name()); os.IsNotExist(err) {
+		t.Fatalf("The config file was not written to disk: %+v", err)
+	}
+}
+
+// TestConfigUpdateFromFile ensures Config.UpdateFromFile(..) properly
+// updates an already create Config instancec with new data.
+func TestConfigUpdateFromFile(t *testing.T) {
+	// Test with a default configuration
+	c := DefaultConfig()
+	// Make the ToFile calls
+	err := c.UpdateFromFile("testdata/config.toml")
+	// Make sure no errors occurred while populating from the file
+	if err != nil {
+		t.Fatalf("Unable update config from file: %+v", err)
+	}
+
+	// Check fields that should have changed after UpdateFromFile
+	if c.Storage != "overlay2" {
+		t.Fatalf("Update failed. Storage did not change to overlay2")
+	}
+
+	if c.RuntimeConfig.PidsLimit != 2048 {
+		t.Fatalf("Update failed. RuntimeConfig.PidsLimit did not change to 2048")
+	}
+}