Added test to validate the date format strings in translations

tests/src/com/fsck/k9/TranslationTest.java

@@ -0,0 +1,41 @@
+package com.fsck.k9;
+
+import com.fsck.k9.activity.K9Activity;
+import com.fsck.k9.helper.DateFormatter;
+
+import android.content.Context;
+import android.content.res.Resources;
+import android.test.AndroidTestCase;
+
+public class TranslationTest extends AndroidTestCase {
+	public void testDateFormats() {
+		forAllLanguages(new LanguageSpecific() {
+			@Override
+			public void runWithLanguage(Context context, String language) {
+				Resources res = context.getResources();
+				String dateFormatCommon = res.getString(R.string.date_format_common);
+				try {
+					DateFormatter.getDateFormat(mContext, dateFormatCommon);
+				} catch (Exception e) {
+					fail("Invalid date format string \"" + dateFormatCommon +
+							"\" for language \"" + language + "\"");
+				}
+			}
+		});
+	}
+
+	private void forAllLanguages(LanguageSpecific action) {
+		Resources res = mContext.getResources();
+		String[] languages = res.getStringArray(R.array.supported_languages);
+
+		for (String lang : languages) {
+			K9Activity.setLanguage(mContext, lang);
+
+			action.runWithLanguage(mContext, lang);
+		}
+	}
+
+	interface LanguageSpecific {
+		void runWithLanguage(Context context, String language);
+	}
+}