From 3b480cdfd5f0c44e4cc06b0aeb160c4512953ff3 Mon Sep 17 00:00:00 2001
From: John Firebaugh <john.firebaugh@gmail.com>
Date: Thu, 13 Sep 2018 16:40:38 -0700
Subject: [PATCH] Auto-convert format arguments to strings

---
 .../expression/definitions/formatted.js       |  4 +-
 .../{formatted => format}/basic/test.json     |  0
 .../format/coercion/test.json                 | 50 +++++++++++++++++++
 .../{formatted => format}/to-string/test.json |  0
 4 files changed, 52 insertions(+), 2 deletions(-)
 rename test/integration/expression-tests/{formatted => format}/basic/test.json (100%)
 create mode 100644 test/integration/expression-tests/format/coercion/test.json
 rename test/integration/expression-tests/{formatted => format}/to-string/test.json (100%)

diff --git a/src/style-spec/expression/definitions/formatted.js b/src/style-spec/expression/definitions/formatted.js
index d6e517479b1..ef4a74b86c3 100644
--- a/src/style-spec/expression/definitions/formatted.js
+++ b/src/style-spec/expression/definitions/formatted.js
@@ -1,7 +1,7 @@
 // @flow
 
 import { NumberType, ValueType, FormattedType, array, StringType } from '../types';
-
+import { toString } from '../values';
 
 import type { Expression } from '../expression';
 import type EvaluationContext from '../evaluation_context';
@@ -101,7 +101,7 @@ export class FormatExpression implements Expression {
         return new Formatted(
             this.sections.map(section =>
                 new FormattedSection(
-                    section.text.evaluate(ctx) || "",
+                    toString(section.text.evaluate(ctx)),
                     section.scale ? section.scale.evaluate(ctx) : null,
                     section.font ? section.font.evaluate(ctx).join(',') : null
                 )
diff --git a/test/integration/expression-tests/formatted/basic/test.json b/test/integration/expression-tests/format/basic/test.json
similarity index 100%
rename from test/integration/expression-tests/formatted/basic/test.json
rename to test/integration/expression-tests/format/basic/test.json
diff --git a/test/integration/expression-tests/format/coercion/test.json b/test/integration/expression-tests/format/coercion/test.json
new file mode 100644
index 00000000000..e7570b146ab
--- /dev/null
+++ b/test/integration/expression-tests/format/coercion/test.json
@@ -0,0 +1,50 @@
+{
+  "expression": [
+    "format",
+    ["get", "a"],
+    {},
+    ["get", "1"],
+    {},
+    ["get", "true"],
+    {}
+  ],
+  "inputs": [[{}, {"properties": {"a": "a", "1": 1, "true": true}}]],
+  "expected": {
+    "compiled": {
+      "result": "success",
+      "isFeatureConstant": false,
+      "isZoomConstant": true,
+      "type": "formatted"
+    },
+    "outputs": [
+      {
+        "sections": [
+          {
+            "text": "a",
+            "scale": null,
+            "fontStack": null
+          },
+          {
+            "text": "1",
+            "scale": null,
+            "fontStack": null
+          },
+          {
+            "text": "true",
+            "scale": null,
+            "fontStack": null
+          }
+        ]
+      }
+    ],
+    "serialized": [
+      "format",
+      ["get", "a"],
+      {},
+      ["get", "1"],
+      {},
+      ["get", "true"],
+      {}
+    ]
+  }
+}
diff --git a/test/integration/expression-tests/formatted/to-string/test.json b/test/integration/expression-tests/format/to-string/test.json
similarity index 100%
rename from test/integration/expression-tests/formatted/to-string/test.json
rename to test/integration/expression-tests/format/to-string/test.json