Added spec + tests for the GetFieldMapping API

Introduced in elastic#3941

rest-api-spec/api/indices.get_field_mapping.json

@@ -0,0 +1,31 @@
+{
+  "indices.get_mapping": {
+    "documentation": "http://www.elasticsearch.org/guide/reference/api/admin-indices-get-mapping/",
+    "methods": ["GET"],
+    "url": {
+      "path": "/_mapping/field/{field}",
+      "paths": ["/_mapping/field/{field}", "/{index}/_mapping/field/{field}", "/{index}/{type}/_mapping/field/{field}"],
+      "parts": {
+        "index": {
+          "type" : "list",
+          "description" : "A comma-separated list of index names"
+        },
+        "type": {
+          "type" : "list",
+          "description" : "A comma-separated list of document types"
+        },
+        "field": {
+          "type" : "list",
+          "description" : "A comma-separated list of fields"
+        }
+      },
+      "params": {
+        "include_defaults": {
+          "type" : "boolean",
+          "description" : "specifies default mapping values should be returned"
+        }
+      }
+    },
+    "body": null
+  }
+}

rest-api-spec/test/indices.get_field_mapping/10_basic.yaml

@@ -0,0 +1,68 @@
+---
+setup:
+  - skip:
+      version:  "0 - 0.90.5"
+      reason:   "get field mapping was added in 0.90.6"
+
+  - do:
+        indices.create:
+          index: test_index
+          body:
+              mappings:
+                test_type:
+                  properties:
+                    text:
+                      type:     string
+
+---
+"Get field mapping with no index and type":
+  - do:
+      indices.get_field_mapping:
+        field: text
+
+  - match: {test_index.test_type.text.mapping.text.type:     string}
+
+---
+"Get field mapping by index only":
+  - do:
+      indices.get_field_mapping:
+        index: test_index
+        field: text
+
+  - match: {test_index.test_type.text.mapping.text.type:     string}
+
+---
+"Get field mapping by type & field":
+
+  - do:
+      indices.get_field_mapping:
+        index: test_index
+        type: test_type
+        field: text
+
+  - match: {test_index.test_type.text.mapping.text.type:     string}
+
+---
+"Get field mapping by type & field, with another field that doesn't exist":
+
+  - do:
+      indices.get_field_mapping:
+        index: test_index
+        type: test_type
+        field: [ text , text1 ]
+
+  - match: {test_index.test_type.text.mapping.text.type:     string}
+  - is_false: test_index.test_type.text1
+
+---
+"Get field mapping with include_defaults":
+
+  - do:
+      indices.get_field_mapping:
+        index: test_index
+        type: test_type
+        field: text
+        include_defaults: true
+
+  - match: {test_index.test_type.text.mapping.text.type:     string}
+  - match: {test_index.test_type.text.mapping.text.analyzer: default}

rest-api-spec/test/indices.get_field_mapping/20_missing_field.yaml

@@ -0,0 +1,24 @@
+---
+"Raise 404 when field doesn't exist":
+  - skip:
+      version:  "0 - 0.90.5"
+      reason:   "get field mapping was added in 0.90.6"
+
+  - do:
+        indices.create:
+          index: test_index
+          body:
+              mappings:
+                test_type:
+                  properties:
+                    text:
+                      type:     string
+                      analyzer: whitespace
+
+  - do:
+      catch: missing
+      indices.get_field_mapping:
+        index: test_index
+        type: test_type
+        field: not_text
+

rest-api-spec/test/indices.get_field_mapping/30_missing_type.yaml

@@ -0,0 +1,24 @@
+---
+"Raise 404 when type doesn't exist":
+  - skip:
+      version:  "0 - 0.90.5"
+      reason:   "get field mapping was added in 0.90.6"
+
+  - do:
+        indices.create:
+          index: test_index
+          body:
+              mappings:
+                test_type:
+                  properties:
+                    text:
+                      type:     string
+                      analyzer: whitespace
+
+  - do:
+      catch: missing
+      indices.get_field_mapping:
+        index: test_index
+        type: not_test_type
+        field: text
+

rest-api-spec/test/indices.get_field_mapping/40_missing_index.yaml

@@ -0,0 +1,14 @@
+---
+"Raise 404 when index doesn't exist":
+  - skip:
+      version:  "0 - 0.90.5"
+      reason:   "get field mapping was added in 0.90.6"
+
+  - do:
+      catch: missing
+      indices.get_mapping:
+        index: test_index
+        type: type
+        field: field
+
+