Added toJson/toString functions.

src/main/kotlin/net/thauvin/erik/crypto/CryptoPrice.kt

@@ -37,6 +37,7 @@ import okhttp3.OkHttpClient
 import okhttp3.Request
 import org.json.JSONException
 import org.json.JSONObject
+import org.json.JSONStringer
 import java.io.IOException
 import java.math.BigDecimal
 import java.text.NumberFormat
@@ -150,4 +151,24 @@ open class CryptoPrice(val base: String, val currency: String, val amount: BigDe
             it.format(amount)
         }
     }
+
+    /**
+     * Return a JSON representation of the [CryptoPrice].
+     */
+    fun toJson(): String {
+        return JSONStringer()
+                .`object`().key("data")
+                .`object`()
+                .key("base").value(base)
+                .key("currency").value(currency)
+                .key("amount").value(amount.toString())
+                .endObject()
+                .endObject()
+                .toString()
+    }
+
+    /**
+     * Return a JSON respresentation of the [CryptoPrice].
+     */
+    override fun toString(): String = toJson()
 }

src/test/kotlin/net/thauvin/erik/crypto/CryptoPriceTest.kt

@@ -12,9 +12,11 @@ import kotlin.test.assertFailsWith
 import kotlin.test.assertTrue
 
 /**
- * The `CryptoPriceTest` class.
+ * [CryptoPrice] Tests
  */
 class CryptoPriceTest {
+    val jsonData = "{\"data\":{\"base\":\"BTC\",\"currency\":\"USD\",\"amount\":\"%s\"}}"
+
     @Test
     @Throws(CryptoException::class)
     fun testBTCPrice() {
@@ -108,15 +110,27 @@ class CryptoPriceTest {
         assertEquals("$12,345.6", usd.toCurrency(minFractionDigits = 0), "minFractionDigits = 0")
     }
 
+    @Test
+    fun testToJson() {
+        listOf("1234.5", "1234.56", "1234.567").forEach {
+            val json = jsonData.format(it)
+            with(json.toPrice()) {
+                assertEquals(json, toJson(), "toJson($it)")
+                assertEquals(json, toString(), "toString($it)")
+            }
+        }
+    }
+
+
     @Test
     @Throws(CryptoException::class)
     fun testToPrice() {
         val d = "57515.60"
-        val json = "{\"data\":{\"base\":\"BTC\",\"currency\":\"USD\",\"amount\":\"$d\"}}"
+        val json = jsonData.format(d)
         val price = json.toPrice()
         assertEquals("BTC", price.base, "base is BTC")
         assertEquals("USD", price.currency, "currency is USD")
-        assertEquals(d, price.amount.toString(), "amount is 57515.60")
+        assertEquals(d, price.amount.toString(), "amount is $d")
 
         assertFailsWith(
             message = "double conversion did not fail",