Add convenience wrapper for getting strings from ValueMismatch.

Author: alexander-yevsyukov

build.gradle

@@ -54,7 +54,7 @@ allprojects {
     apply plugin: 'idea'
 
     group = 'org.spine3'
-    version = '0.5.18-SNAPSHOT'
+    version = '0.5.19-SNAPSHOT'
 }
 
 ext {

client/src/main/java/org/spine3/base/Mismatch.java

@@ -20,11 +20,14 @@
 
 package org.spine3.base;
 
+import com.google.protobuf.InvalidProtocolBufferException;
 import com.google.protobuf.Message;
+import com.google.protobuf.StringValue;
 import org.spine3.protobuf.AnyPacker;
 
 import javax.annotation.Nullable;
 
+import static com.google.common.base.Throwables.propagate;
 import static org.spine3.protobuf.Values.pack;
 
 /**
@@ -157,4 +160,35 @@ public static ValueMismatch of(@Nullable Message expected, @Nullable Message act
         builder.setVersion(version);
         return builder.build();
     }
+
+
+    /**
+     * Obtains expected string from the passed mismatch.
+     *
+     * @throws RuntimeException if the passed instance represent a mismatch of non-string values
+     */
+    public static String getExpectedString(ValueMismatch mismatch) {
+        try {
+            final StringValue result = mismatch.getExpected()
+                                               .unpack(StringValue.class);
+            return result.getValue();
+        } catch (InvalidProtocolBufferException e) {
+            throw propagate(e);
+        }
+    }
+
+    /**
+     * Obtains actual string from the passed mismatch.
+     *
+     * @throws RuntimeException if the passed instance represent a mismatch of non-string values
+     */
+    public static String getActualString(ValueMismatch mismatch) {
+        try {
+            final StringValue result = mismatch.getActual()
+                                               .unpack(StringValue.class);
+            return result.getValue();
+        } catch (InvalidProtocolBufferException e) {
+            throw propagate(e);
+        }
+    }
 }

client/src/test/java/org/spine3/base/MismatchShould.java

@@ -30,6 +30,8 @@
 
 import static org.junit.Assert.assertEquals;
 import static org.junit.Assert.assertTrue;
+import static org.spine3.base.Mismatch.getActualString;
+import static org.spine3.base.Mismatch.getExpectedString;
 import static org.spine3.protobuf.AnyPacker.unpack;
 import static org.spine3.protobuf.Values.newStringValue;
 import static org.spine3.test.Tests.hasPrivateUtilityConstructor;
@@ -83,7 +85,6 @@ public void return_mismatch_object_with_string_values() {
     public void return_mismatch_object_with_int32_values() {
         final int expected = 0;
         final int actual = 1;
-        final int requested = 2;
         final ValueMismatch mismatch = Mismatch.of(expected, actual, VERSION);
         final Int32Value expectedWrapper = unpack(mismatch.getExpected());
         final Int32Value actualWrapper = unpack(mismatch.getActual());
@@ -96,7 +97,6 @@ public void return_mismatch_object_with_int32_values() {
     public void return_mismatch_object_with_int64_values() {
         final long expected = 0L;
         final long actual = 1L;
-        final long requested = 2L;
         final ValueMismatch mismatch = Mismatch.of(expected, actual, VERSION);
         final Int64Value expectedWrapped = unpack(mismatch.getExpected());
         final Int64Value actualWrapped = unpack(mismatch.getActual());
@@ -109,7 +109,6 @@ public void return_mismatch_object_with_int64_values() {
     public void return_mismatch_object_with_float_values() {
         final float expected = 0.0F;
         final float actual = 1.0F;
-        final float requested = 2.0F;
         final ValueMismatch mismatch = Mismatch.of(expected, actual, VERSION);
         final FloatValue expectedWrapped = unpack(mismatch.getExpected());
         final FloatValue actualWrapped = unpack(mismatch.getActual());
@@ -122,7 +121,6 @@ public void return_mismatch_object_with_float_values() {
     public void return_mismatch_object_with_double_values() {
         final double expected = 0.1;
         final double actual = 0.2;
-        final double requested = 0.3;
         final ValueMismatch mismatch = Mismatch.of(expected, actual, VERSION);
         final DoubleValue expectedWrapped = unpack(mismatch.getExpected());
         final DoubleValue actualWrapped = unpack(mismatch.getActual());
@@ -135,7 +133,6 @@ public void return_mismatch_object_with_double_values() {
     public void return_mismatch_object_with_boolean_values() {
         final boolean expected = true;
         final boolean actual = false;
-        final boolean requested = true;
         final ValueMismatch mismatch = Mismatch.of(expected, actual, VERSION);
         final BoolValue expectedWrapped = unpack(mismatch.getExpected());
         final BoolValue actualWrapped = unpack(mismatch.getActual());
@@ -171,4 +168,16 @@ public void return_mismatch_object_with_message_values() {
         assertEquals(EXPECTED, expected.getValue());
         assertEquals(ACTUAL, actual.getValue());
     }
+
+    @Test
+    public void return_expected_string() {
+        final ValueMismatch mismatch = Mismatch.of(newStringValue(EXPECTED), newStringValue(ACTUAL), VERSION);
+        assertEquals(EXPECTED, getExpectedString(mismatch));
+    }
+
+    @Test
+    public void return_actual_string() {
+        final ValueMismatch mismatch = Mismatch.of(newStringValue(EXPECTED), newStringValue(ACTUAL), VERSION);
+        assertEquals(ACTUAL, getActualString(mismatch));
+    }
 }