feat(import path): Support absolute paths and NODE_PATH (#37)

Resolves #36.

About NODE_PATH, we use to have this setting with projects created via create-react-app.

cc @evenchange4

src/__tests__/__snapshots__/macro.test.js.snap

@@ -214,6 +214,110 @@ const query = {
 
 `;
 
+exports[`macros [loader] with absolute path and NODE_PATH: [loader] with absolute path and NODE_PATH 1`] = `
+
+import { loader } from 'graphql.macro';
+const query = loader('__tests__/fixtures/simpleFragment.graphql');
+
+      ↓ ↓ ↓ ↓ ↓ ↓
+
+const query = {
+  "kind": "Document",
+  "definitions": [{
+    "kind": "FragmentDefinition",
+    "name": {
+      "kind": "Name",
+      "value": "UserEntry1"
+    },
+    "typeCondition": {
+      "kind": "NamedType",
+      "name": {
+        "kind": "Name",
+        "value": "User"
+      }
+    },
+    "directives": [],
+    "selectionSet": {
+      "kind": "SelectionSet",
+      "selections": [{
+        "kind": "Field",
+        "name": {
+          "kind": "Name",
+          "value": "firstName"
+        },
+        "arguments": [],
+        "directives": []
+      }]
+    }
+  }],
+  "loc": {
+    "start": 0,
+    "end": 44,
+    "source": {
+      "body": "fragment UserEntry1 on User {\\n  firstName\\n}\\n",
+      "name": "GraphQL request",
+      "locationOffset": {
+        "line": 1,
+        "column": 1
+      }
+    }
+  }
+};
+
+`;
+
+exports[`macros [loader] with absolute path: [loader] with absolute path 1`] = `
+
+import { loader } from 'graphql.macro';
+const query = loader('src/__tests__/fixtures/simpleFragment.graphql');
+
+      ↓ ↓ ↓ ↓ ↓ ↓
+
+const query = {
+  "kind": "Document",
+  "definitions": [{
+    "kind": "FragmentDefinition",
+    "name": {
+      "kind": "Name",
+      "value": "UserEntry1"
+    },
+    "typeCondition": {
+      "kind": "NamedType",
+      "name": {
+        "kind": "Name",
+        "value": "User"
+      }
+    },
+    "directives": [],
+    "selectionSet": {
+      "kind": "SelectionSet",
+      "selections": [{
+        "kind": "Field",
+        "name": {
+          "kind": "Name",
+          "value": "firstName"
+        },
+        "arguments": [],
+        "directives": []
+      }]
+    }
+  }],
+  "loc": {
+    "start": 0,
+    "end": 44,
+    "source": {
+      "body": "fragment UserEntry1 on User {\\n  firstName\\n}\\n",
+      "name": "GraphQL request",
+      "locationOffset": {
+        "line": 1,
+        "column": 1
+      }
+    }
+  }
+};
+
+`;
+
 exports[`macros [loader] with fragment: [loader] with fragment 1`] = `
 
 import { loader } from 'graphql.macro';

src/__tests__/fixtures/simpleFragment.graphql

@@ -0,0 +1,3 @@
+fragment UserEntry1 on User {
+  firstName
+}

src/__tests__/macro.test.js

@@ -65,6 +65,23 @@ pluginTester({
         const query = loader('./fixtures/query1.graphql');
       `,
     },
+    '[loader] with absolute path': {
+      error: false,
+      code: `
+        import { loader } from '../macro';
+        const query = loader('src/__tests__/fixtures/simpleFragment.graphql');
+      `,
+    },
+    '[loader] with absolute path and NODE_PATH': {
+      error: false,
+      code: `
+        import { loader } from '../macro';
+        const query = loader('__tests__/fixtures/simpleFragment.graphql');
+      `,
+      setup: () => {
+        process.env.NODE_PATH = 'src/';
+      },
+    },
     '[loader] with nested circular fragments': {
       error: false,
       code: `

src/macro.js

@@ -1,5 +1,6 @@
 // @flow
 import path from 'path';
+import fs from 'fs';
 import { createMacro } from 'babel-plugin-macros';
 import gqlTag from 'graphql-tag';
 import serialize from 'babel-literal-to-ast';
@@ -8,6 +9,10 @@ import compileWithFragment from './utils/compileWithFragment';
 // import printAST from 'ast-pretty-print';
 // console.log(printAST(referencePath.parentPath))
 
+const cwd = fs.realpathSync(process.cwd());
+const resolvePathFromCwd = relativePath =>
+  path.resolve(cwd, process.env.NODE_PATH || '.', relativePath);
+
 function graphqlMacro({
   references,
   state: { file: { opts: { filename } } },
@@ -28,7 +33,9 @@ function graphqlMacro({
   // Case 2: import { loader } from 'graphql.macro'
   loader.forEach(referencePath => {
     referencePath.parentPath.node.arguments.forEach(({ value }) => {
-      const queryPath = path.join(filename, '..', value);
+      const queryPath = value.startsWith('./')
+        ? path.join(filename, '..', value)
+        : resolvePathFromCwd(value);
       const expanded = expandImports(queryPath); // Note: #import feature
       referencePath.parentPath.replaceWith(serialize(gqlTag(expanded)));
     });