Added CompareArrays func for comparing JSON arrays

As well as CompareSlices for unmarshaling slices and LoadFixtureAsArray for unmarshaling JSON array from file into []interface{}

Signed-off-by: Alexey Knyshev <alexey.knyshev@gmail.com>

FIXTURES/array.json

@@ -0,0 +1,10 @@
+[
+    1,
+    2,
+    6,
+    {
+        "str": "bcded",
+        "arr": [ "a", "b", 37.8 ]
+    },
+    "string"
+]

FIXTURES/array_changed.json

@@ -0,0 +1,10 @@
+[
+    1,
+    2,
+    6,
+    {
+        "str": "bcdef",
+        "arr": [ "a", "b", 37.8 ]
+    },
+    "string"
+]

gojsondiff_test.go

@@ -80,6 +80,38 @@ var _ = Describe("Gojsondiff", func() {
 				})
 			})
 		})
+		Describe("CompareArrays", func() {
+
+			var (
+				a, b   []interface{}
+				differ *Differ
+			)
+
+			BeforeEach(func() {
+				differ = New()
+			})
+
+			Context("There are no difference between the two JSON strings", func() {
+				It("Detects nothing", func() {
+					a = LoadFixtureAsArray("FIXTURES/array.json")
+					b = LoadFixtureAsArray("FIXTURES/array.json")
+
+					diff := differ.CompareArrays(a, b)
+					Expect(diff.Modified()).To(BeFalse())
+				})
+			})
+
+			Context("There are some values modified", func() {
+				It("Detects changes", func() {
+					a = LoadFixtureAsArray("FIXTURES/array.json")
+					b = LoadFixtureAsArray("FIXTURES/array_changed.json")
+
+					diff := differ.CompareArrays(a, b)
+					Expect(diff.Modified()).To(BeTrue())
+					Expect(len(diff.Deltas())).To(Equal(1))
+				})
+			})
+		})
 		Describe("Compare", func() {
 			Context("There are some values modified", func() {
 				It("Detects changes", func() {

tests/helper.go

@@ -19,3 +19,16 @@ func LoadFixture(file string) map[string]interface{} {
 	}
 	return result
 }
+
+func LoadFixtureAsArray(file string) []interface{} {
+	content, err := ioutil.ReadFile(file)
+	if err != nil {
+		Fail("Fixture file '" + file + "' not found.")
+	}
+	var result []interface{}
+	err = json.Unmarshal(content, &result)
+	if err != nil {
+		Fail("Unmarshaling JSON of '" + file + "' failed: " + err.Error())
+	}
+	return result
+}