#820 Fix Hamcrest matcher error message

json-unit-core/src/main/java/net/javacrumbs/jsonunit/core/internal/HamcrestHandler.java

@@ -34,6 +34,9 @@ void matchHamcrestMatcher(Context context, Node actualNode, Matcher patternMatch
             Object value = actualNode.getValue();
             if (!matcher.matches(value)) {
                 Description description = new StringDescription();
+                description.appendText("Expected ");
+                matcher.describeTo(description);
+                description.appendText(" but ");
                 matcher.describeMismatch(value, description);
                 valueDifferenceReporter.differenceFound(
                         context,

json-unit-spring/src/test/java/net/javacrumbs/jsonunit/spring/testit/WebTestClientTest.java

@@ -104,7 +104,7 @@ void useMatcher() {
                         .node("result.decimal")
                         .isEqualTo("${json-unit.matches:negative}")))
                 .hasMessage(
-                        "JSON documents are different:\nMatcher \"negative\" does not match value 1.00001 in node \"result.decimal\". <1.00001> was greater than <0>\n");
+                        "JSON documents are different:\nMatcher \"negative\" does not match value 1.00001 in node \"result.decimal\". Expected a value less than <0> but <1.00001> was greater than <0>\n");
     }
 
     @Test

tests/test-base/src/main/java/net/javacrumbs/jsonunit/test/base/AbstractAssertJTest.java

@@ -1311,7 +1311,7 @@ void ifMatcherDoesNotMatchReportDifference() {
                         .withDifferenceListener(listener)
                         .isEqualTo("{\"test\": \"${json-unit.matches:positive}\"}"))
                 .hasMessage(
-                        "JSON documents are different:\nMatcher \"positive\" does not match value -1 in node \"test\". <-1> was less than <0>\n");
+                        "JSON documents are different:\nMatcher \"positive\" does not match value -1 in node \"test\". Expected a value greater than <0> but <-1> was less than <0>\n");
 
         assertThat(listener.getDifferenceList()).hasSize(1);
         assertThat(listener.getDifferenceList().get(0).toString())
@@ -1327,7 +1327,7 @@ void parametrizedMatcherShouldFail() {
                     .isEqualTo("{\"test\": \"${json-unit.matches:isDivisibleBy}3\"}");
         } catch (AssertionError e) {
             assertEquals(
-                    "JSON documents are different:\nMatcher \"isDivisibleBy\" does not match value 5 in node \"test\". It is not divisible by <3>\n",
+                    "JSON documents are different:\nMatcher \"isDivisibleBy\" does not match value 5 in node \"test\". Expected value divisible by <3> but was <5>\n",
                     e.getMessage());
         }
     }
@@ -2311,6 +2311,28 @@ void shouldFailFast() {
                     """);
     }
 
+    @Test
+    void hamcrestMessageTest() {
+        assertThatThrownBy(
+                        () -> assertThatJson("""
+        {
+          "someText": "abc123"
+        }
+        """)
+                                .withMatcher("exampleMatcher", org.hamcrest.Matchers.equalTo("def456"))
+                                .isEqualTo(
+                                        """
+            {
+              "someText": "${json-unit.matches:exampleMatcher}"
+            }
+            """))
+                .hasMessage(
+                        """
+            JSON documents are different:
+            Matcher "exampleMatcher" does not match value "abc123" in node "someText". Expected "def456" but was "abc123"
+            """);
+    }
+
     private static final String json =
             """
         {

tests/test-base/src/main/java/net/javacrumbs/jsonunit/test/base/AbstractJsonAssertTest.java

@@ -1049,7 +1049,7 @@ void parametrizedMatcherShouldFail() {
                     JsonAssert.withMatcher("isDivisibleBy", divisionMatcher));
         } catch (AssertionError e) {
             assertEquals(
-                    "JSON documents are different:\nMatcher \"isDivisibleBy\" does not match value 5 in node \"test\". It is not divisible by <3>\n",
+                    "JSON documents are different:\nMatcher \"isDivisibleBy\" does not match value 5 in node \"test\". Expected value divisible by <3> but was <5>\n",
                     e.getMessage());
         }
     }
@@ -1102,7 +1102,7 @@ void parameterMatchingShouldWork() {
                         """
                 JSON documents are different:
                 Different value found when comparing expected array element test[0] to actual element test[1].
-                Matcher "eq" does not match value 2 in node "test[1]".\s
+                Matcher "eq" does not match value 2 in node "test[1]". Expected number equal to <1> but was <2>
                 """);
     }
 
@@ -1116,12 +1116,7 @@ public boolean matches(Object item) {
 
         @Override
         public void describeTo(Description description) {
-            description.appendValue(param);
-        }
-
-        @Override
-        public void describeMismatch(Object item, Description description) {
-            description.appendText("It is not divisible by ").appendValue(param);
+            description.appendText("value divisible by ").appendValue(param);
         }
 
         @Override
@@ -1163,12 +1158,9 @@ public boolean matches(Object item) {
 
         @Override
         public void describeTo(Description description) {
-            description.appendValue(param);
+            description.appendText("number equal to ").appendValue(param);
         }
 
-        @Override
-        public void describeMismatch(Object item, Description description) {}
-
         @Override
         public void setParameter(String parameter) {
             this.param = new BigDecimal(parameter);
@@ -1295,7 +1287,7 @@ void ifMatcherDoesNotMatchReportDifference() {
                         "{\"test\":-1}",
                         withMatcher("positive", greaterThan(valueOf(0)))))
                 .hasMessage(
-                        "JSON documents are different:\nMatcher \"positive\" does not match value -1 in node \"test\". <-1> was less than <0>\n");
+                        "JSON documents are different:\nMatcher \"positive\" does not match value -1 in node \"test\". Expected a value greater than <0> but <-1> was less than <0>\n");
     }
 
     @Test

tests/test-base/src/main/java/net/javacrumbs/jsonunit/test/base/AbstractJsonFluentAssertTest.java

@@ -476,7 +476,7 @@ void ifMatcherDoesNotMatchReportDifference() {
                         .withDifferenceListener(listener)
                         .isEqualTo("{\"test\": \"#{json-unit.matches:positive}\"}"))
                 .hasMessage(
-                        "JSON documents are different:\nMatcher \"positive\" does not match value -1 in node \"test\". <-1> was less than <0>\n");
+                        "JSON documents are different:\nMatcher \"positive\" does not match value -1 in node \"test\". Expected a value greater than <0> but <-1> was less than <0>\n");
         assertThat(listener.getDifferenceList()).hasSize(1);
         assertThat(listener.getDifferenceList().get(0).toString())
                 .isEqualTo("DIFFERENT Expected #{json-unit.matches:positive} in test got -1 in test");

tests/test-base/src/main/java/net/javacrumbs/jsonunit/test/base/AbstractJsonMatchersTest.java

@@ -131,7 +131,7 @@ void ifMatcherDoesNotMatchReportDifference() {
 
                 Expected: {"test": "${json-unit.matches:positive}"}
                      but: JSON documents are different:
-                Matcher "positive" does not match value -1 in node "test". <-1> was less than <0>
+                Matcher "positive" does not match value -1 in node "test". Expected a value greater than <0> but <-1> was less than <0>
                 """);
     }